Zak Smith

Stage 3. Arvada Ranch. The helicopter was back this year. Each shooter was provided with 3 30-round magazines for a provided AR-15, and there were more targets opportunities per pass. Making hits, however, was much more difficult due to increased velocity and distance in the helicopter. The helicopter event was not scored as part of the "main match." The second part of Stage 3 was the field course. Minimum round count was 56 carbine and 79 rifle. Just like Stage 2, the distance was 1.5 miles and the time limit was 1 hour. The path was more or less down hill and followed a road, making it less physically demanding. But there was no free lunch. The targets on this stage were smaller and more difficult to locate, and the wind - at least on day 3 - was tricky. [ link to LARGER image ] [ link to LARGER image ] This stage had 7 stations. The rifle shooter had no targets until station 3, but at station 7, he had 25 rifle targets. Locating and successfully engaging 25 rifle targets on the last station was a challenge due to sheer number of targets available, and the heat caused by shooting 50+ rounds in a short period of time caused many rifles' point of impacts to "wander". [ link to LARGER image ] My partner shot this course with maybe only 6 misses. I had a harder time with the distant and small rifle targets, with tricky wind. Due to the pressure in locating the targets under time, I felt more harried during this stage and that contributed to some bad "presses." We finished the last target with about 90 seconds to spare. [ link to LARGER image ] [ link to LARGER image ]

Stage 2. Hoblit Ranch. This course was 1.5 miles cross-country with a time limit of 1 hour. Minimum round count 2 pistol, 62 carbine, 59 rifle. The course had five stations with carbine and pistol targets at each. There was one pistol target at Stage 1. This was the most physically demanding course of fire, with the most rugged terrain. Carbine targets tended to be in arrays of 3-5, and rifle targets were generally grouped into strings of 2-4 with 10-50 yards between targets. [ link to LARGER image ] We had pulled the 0630 time slot, so we shot each course of fire just after dawn. This was generally an advantage for temperature and wind, but it made locating targets in shadow difficult. [ link to LARGER image ] Many teams including ours had trouble with station 1's rifle targets, but besides that, we shot well on this course with few misses. We finished the final station with 9 minutes to spare, and hit the +250/-250 point bonus target on station 4. The scoring on Stages 2 and 3 was: +40 per rifle hit, +10 per carbine hit, -20 per miss, pistol +10, pistol misses not counted. [ link to LARGER image ]

Last year we had a limited number of 45ACP double-stack mags (about 7) and I had to reload them on the fly. This year we entered the course of fire with 450 rounds preloaded in Glock 19 and 17 magazines. All my partner had to do was pick up the empties which I dropped every 3-4 targets. I carried a SAW-type pouch with approx 20 15 and 17 round Glock magazines. [ link to LARGER image ] [ link to LARGER image ] The shoot-house is a football-field size structure of walls, busses, and other props, with targets - both paper and steel - strewn throughout. The shooter had to pay careful attention in order to not walk past targets. [ link to LARGER image ] Like last year, the carbine got extremely hot-- [ link to LARGER image ]

Zak's 2005 ITRC Report As background, read the 2004 ITRC Report. The D&L Sports International Tactical Rifleman Championships (ITRC) is a "3 Gun" match unlike conventional 3Gun matches. This match has field courses from 1 to 2.5 miles long which must be finished in times from 45 minutes to two hours by teams of two: a bolt rifle shooter, and a carbine shooter. Dave Lauck's Small Arms Training Academy (SATA) is located about an hour north of Gillette, WY, basically in the middle of nowhere. Match stages were located there and on two ranches within an hour's distance. 2005 was the second year Glenn Frank and I shot the ITRC. Last year he shot the bolt rifle and I the carbine, so this year we switched roles. Our training for this match was both team and individual practice at long distance, small targets, and regular cardio exercise. The Colorado front range 3Gun/rifle crowd fielded 5 teams this year, in addition to Burris, who sent a team from their plant in Greeley. Unlike last year, many of us skipped the sight-in the morning before the match itself. If a team wanted to verify rifles' zeros, they could set up a target on the ubiquitous BLM land near Gillette. Since we all had data printed for Gillette's altitude and typical environmental conditions and good solid zeros, it would likely have been a waste of ammo. In 2004, many of the teams were SWAT or military. Due to deployments, there were very few military teams this year, just a few from Fort Campbell. I thought I heard there were 32 teams, but only 30 showed up on the final scores. This down about 15 from the number of starting teams in 2004, and down about 5 from the number of finishing teams. The match was divided into 3 courses. Each team shot one course per day. Instead of boring you with lot more of background, here are the stages. They were roughly similar to the stages in 2004, with some changes. Course 1. DL SATA The SATA range was the location for the high-intensity pistol/carbine stage. This course starts with approximately 400 scoring opportunities for the carbine followed by approximately 400 more pistol scoring opportunities in the shoot-house. Each hit on target was worth 1 point; there were no "bonus" or "high value" targets unlike 2004. Each target had to be engaged 4 times, except for pistol steel if knocked down. The team had 25 minutes to engage each of the two halves of the course of fire, so if they ran out of time on the carbine, it would not affect their ability to finish the shoot-house. The team could use a secondary carbine for this course in order to not "burn out" their good match barrel. The course started with the carbine shooter engaging several 100-400 yard arrays of targets from 5 or 6 positions, running a total of maybe 150 yards. Once those targets were engaged, the team proceeded into the back of the pick-up truck. The truck drove past an array of full size poppers, which the carbine shooter engaged. Hits were still worth 1 point. When the truck stopped, the team ran over to the first of 3 platforms which each had 22 steel targets arrayed at about 100 yards. The suggested minimum round count for the carbine was 500. [ link to LARGER image ] Due to dawn glare, we had problems locating some of the targets and timed out on the second to last platform. This lost us about 92 points. We started the stage with about 500 rounds preloaded in 30-round AR15 mags. [ link to LARGER image ] [ link to LARGER image ] I then proceeded to the pistol shoot-house and ran it start to finish in 12 minutes, giving us 13 extra bonus points (one per minute early). I ran past two targets and had two other misses. The recommended round count was 400. I shot 305 rounds. [ link to LARGER image ]

You're right, sorry. I was thinking of the AE.

The "bottom metal" accepts the 10 (actually 11-12) round double-stack AI-AW magazines, while the short-action AICS stock uses the single-stack 5-round AICS mags. (The AI-AW is the rockingest MOR/LR rifle, but it's very expensive.)

Capability Tradeoffs With the background out of the way, What are the capability trade-offs of the different feature choices? Elevation Adjustment Methods Elevation specification can be done by external knobs (or direct mount adjustment, e.g. the Elcan), via reticle features, or a combination. Knobs: If the primary method of specifying elevation is by external knob, the knob will have "click" values. Each time the knob "clicks" to the next setting, the elevation setting will be changed by the click amount. Typical values of clicks are 1/4 MOA, 1/2 MOA, 1 MOA, or 0.1MIL. http://apollo.demigod.org/~zak/DigiCam/AI-...54_5422_img.jpg (Leupold 3.5-10x40mm M1 scope with 1/4 MOA-click external knobs, mounted on an Accuracy International (AI) AWP) Elevation Travel The scope's internal mechanical design and the scope mounts used determine the maximum range for which elevation can be specified. In the specifications for a scope, the maximum elevation travel is described as something like 60 MOA, 80 MOA, 100 MOA, etc. This is the total "top to bottom" travel of the erector assembly inside the tube. If the rifle and mounts are level, the elevation adjustment should be in the middle of its total travel when zeroed. For example, if we start with "0" at the bottom, a scope with 60 total MOA elevation will likely be zeroed at about 30 MOA up from bottom, and cranking it all the way up, it would stop at 60 MOA. In this case, the scope is limited to 40 MOA elevation from center/zero. This will limit the maximum engagement range by limiting the elevation setting that can be dialed. For example, if a certain 308 load needs 31.5 MOA elevation for 1000 yards, the described scope will not be able to dial enough elevation. When it hits its maximum at 60 (30 above center/zero), it will still be 1.5 MOA "short." The way to get around this is to use an inclined scope base. An inclined scope based has some downward "slope" built in. An inclined base with 20 MOA angle will shift the zero point in the scope further away from its top extent. For example, with the 60 MOA scope described before, instead of being zeroed around +30 MOA (its center), it would be zeroed at about 30 - 20 = 10 MOA up from bottom, and have about 30 + 20 = 50 MOA "up" elevation left. Now instead of running out of elevation travel trying to dial 31.5 MOA, the scope will dial freely up another 50 MOA-- when it is dialed to 31.5, it still has 18.5 MOA left for dialing to longer distances. Elevation Adjustment "Click" size The smallest elevation change possible using the scope's mechanism will in part determine the smallest target for which we can specify hold-over at an arbitrary distance. For example, if we have a scope with 1 MOA clicks, at 400 yards that will demarcate 4.2", so it will not be possible to dial the correct elevation to hit a 3" target at 400 yards with this setup. One adjustment setting might be just under the target, and the next would be 1" high over the top of the target. The tradeoff of fine clicks is that more of them are required to achieve the same elevation adjustment. For example, if 15 MOA are required to get to 600 yards, that would be 60 1/4-MOA clicks, but only 15 1-MOA clicks. The large, coarse click values can be faster to adjust in the field, at the expense of fine-grained adjustment ability. (Nightforce 3.5-15x50mm NPR2 with multi-turn, 10MOA, 0.25MOA click knobs, on an AI-AWM rifle.) Zero-stop If an external knob has a "zero stop" feature, the knob will physically stop turning at or near its "zero" setting. When the shooter wants to dial back down to his zero, he can turn it until it stops. A scope without a zero-stop, like the pictured Leupold, has a knob that will keep turning until the erector assembly bottoms out in the scope body tube. Each revolution the knob turns move the knob up or down, just like a jar lid. On a scope without a zero-stop, the shooter typically notes which "hash mark" the zero-revolution corresponds to. Single Turn, Two-Turn, and Multi-Turn Elevation Knobs In many scopes, a larger click size means fewer revolutions of the elevation knob are required to reach its maximum elevation. A good example of this is the Leupold M3 knob, which turns only one revolution but has 1 MOA clicks. The opposite example would be the Leupold M1 knob, which has 3-5 revolutions depending on scope model and 1/4 MOA clicks. http://apollo.demigod.org/~zak/DigiCam/TAC...cd/HI7Y4565.jpg (Leupold MK4 M3 scope on a Remington 700. Photo by Frankie Icenogle used with permission.) Some scopes are designed to have very many small clicks in only one revolution. A good example of this would be the US Optics EREK knob, which has 90 clicks per revolution and can be ordered with 0.25, 0.5, or 0.1MIL click values, which would yield 22.5MOA, 45MOA, or 9.0MIL travel per revolution. Likewise, some scopes are designed to have just two turns of travel, with some indication to the user which revolution the knob is on. The best example is the Schmidt & Bender "Two Turn" PMII scope, which has approximately 27 mils of travel in two revolutions. Even the two-turn scopes have enough travel in the first revolution to shoot to 1000 yards with 308WIN. http://apollo.demigod.org/~zak/DigiCam/TAC...cd/HI7Y4123.jpg (Schmidt & Bender "Two Turn" PMII mounted on an AR10. Photo by Frankie Icenogle used with permission.) A single or two-turn scope simplifies elevation adjustment by freeing the shooter from keeping track of the current revolution of the knob. With a regular M1-style multi-turn knob, the shooter consults his log-book and reads 17MOA, then has to adjust his scope up one full turn (15MOA) and then two MOA past. With a single or two turn scope, he merely turns the knob about 1/3 of one revolution until the markings for 17MOA are visible. Bullet Drop Compensators (BDC) Some scopes come with bullet-drop compensator (BDC) knobs. These knobs are calibrated for a certain load by having markings typically every 100 yards or meters on the knob itself, so the shooter can look for the distance on the knob instead of the angular elevation amount. If the shooter is engaging a target between marked distances, for example 450 yards, he will have to guess or look up in his data which click value between the 400 and 500 yard markings to use. A BDC knob is nothing more than a regular knob with markings that correspond to the load used. Tube Diameter and Mechanical Limit of Elevation Travel When the elevation knob is adjusted, it physically moves an assembly -- some lenses and the reticle -- inside the main tube body of the scope, just "under" the elevation knobs. This assembly is called the "erector" assembly because it inverts ("erects") the image coming from the objective lens. The erector assembly travels up and down as the elevation knob is turned, and left to right as the windage knob is turned. The movement of the erector assembly moves the "zero" of the reticle. The erector's movement within the scope body is limited by the side of the main tube diameter of the scope. Thus the larger the scope tube diameter, the more elevation travel will be mechanically possible. (It is also possible that the elevation knob mechanism itself limits travel before the mechanical limit of the erector. This is most common in "one turn" scopes like the Leupold M3.) Scope tube diameters include: 1" (25.4mm), 30mm, 34mm (Schmidt & Bender), 35mm (US Optics), and 40mm. The advantages of the larger tube diameters are more elevation travel available and a stronger scope. The disadvantage of larger tube diameters is that the selection of scope rings is few, however, there are several high-quality ring sets available for 34 and 35mm tubes. (US Optics 3.2-17x44mm SN-3 with 35mm tube has approx 18 mils total elevation in two turns, ninety 0.1-mil clicks per revolution. Rifle is an AI-AWP.) Reticle Features The second method for elevation specification is to use reticle features. Many reticle designs have hash marks or dots down from the main cross hair which can be used for hold-over. In a FFP scope, the angles demarcated will be the same at any scope magnification. In a SFP scope, the angles demarcated will change as the scope magnification is changed. Thus, without overly complex calculations, reticle-based holdover is most useful in a FFP scope. Just like the "click" sizes, the spacing of the hash marks for reticle holdover in part determine the smallest engage-able target size. For example, if a reticle has 1 MIL demarcations (ie, in a mildot reticle) and you need to shoot a 10" square target at 600 yards, you need to hold approximately 3.4 mils high, so you'd put the target approx 40% of the way from the 3rd to the 4th mark. If the target is small, there is no precise sight picture-- you're holding "in space" again. A more sophisticated reticle designed specifically for reticle-based holdover (and windage) is the Horus. (View through Horus H25 reticle at approx 12x magnification, targets at 100 yards) The Horus H25 reticle is mil-based, with small tick marks ever 0.2mil. A 308 shooter with the H25 reticle can shoot to 1000 yards using the reticle only. For example, at the TACPRO 2005 sniper match, there was a stage in which 5 targets had to be ranged and engaged with one shot each under a strict time limit. I ranged the targets with my laser and wrote their distances on my note-pad. As I moved from target to target, I only needed to look up the drop for that distance and use hold-over in the Horus H25 reticle. I didn't have to fiddle with any knobs. This demonstrates the speed advantage of reticle-based holdover. A shooter should try to memorize his drop values, and it also helps if he can remember the current target distances or have a spotter to communicate them. (Engaging multiple targets with the Horus reticle at TACPRO 2005. Photo by Frankie Icenogle used with permission.) Hybrid Knob & Reticle The last method for elevation specification is a hybrid, where the shooter might dial to an intermediate zero like 500 yards from his primary 100 yard zero, and then use reticle-based hold-under and hold-over for targets closer and further than the intermediate zero distance. Reticle and hybrid holdover has the advantage of being much faster than dialing elevation changes between shots at targets of different range. The downside is that sight picture precision is reduced because of the larger granularity of reticle features vs. typical knob click values. Again at the 2005 TACPRO sniper match, on a stage where I knew the distances beforehand (325, 375, 500), I dialed to 375, and noted the hold-under for 325 (0.4mil), and the holdover (1.1mil). While shooting the stage, I merely used the appropriate hold-under/over points in the reticle. First Focal Plane vs Second Focal Plane In variable power scopes, a first-focal plane (FFP) reticle configuration means that the angular measure of the reticle features stays constant. No matter what magnification it is set at, 1 MOA will be 1 MOA and 1 MIL will demarcate 1 MIL. The FFP comes into play because with a wide range variable scope (my SN3 is 3.2-17x), dialing down the power will widen the field of view. Target to target transition times are drastically improved by widening the field of view. The ability to locate targets is enhanced by a wider field of view. To use reticle based holdover without the need to adjust to a specific magnification setting, the scope must have a FFP reticle. Another advantage of the FFP is that ranging and miss-spotting can be done at any power and yield direct accurate results. Exit pupil size numbers increase as the scope magnification is dialed down. That's the math behind the observation that a scope at a lower power will produce a brighter image than the same scope dialed up in power. During the day it doesn't make a difference. During the night, it makes a big difference in target ID and sight picture. For an illuminated reticle to be useful, its features need to demarcate the same at whatever magnification is needed for low light. A FFP reticle setup allows reticle-based and hybrid reticle/click holdover to be used at any magnification setting. There are some disadvantages to a FFP reticle in certain situations. As the magnification is increased, the width of the lines which comprise the reticle increase in apparent size and will obscure more of the target than the fine lines in a SFP reticle. Conversely, when the magnification is set near the bottom, for example at 4x on a 3.2-17x optic, the reticle lines "shrink" in size along with the target image and may become difficult or impossible to see in some lighting conditions due to their very fine width. Windage specification Windage works just the same as elevation. Knob clicks or reticle features can be used. The big difference is that the amount of wind hold off is much less than the maximum elevation required for the cartridge's maximum range. A typical 308 load might have 8 MOA deflection with a 20mph cross-wind at 800 yards, while it needs about 18 MOA of elevation at that distance. This means that windage travel is typically not an issue. Because wind changes can be very dynamic, using the reticle for windage hold-off can be more effective than dialing wind. For example, by the time you notice the wind and dial a correction, it may have changed already. Using reticle windage hold-off can be immediate. Lead specification Again, lead works basically the same as windage. MIL vs. MOA In principle, either system can be used. If you're thinking about or communicating elevation values (for example looking at data and then dialing or holding off), a typical elevation value in MOA for 308 looks like "11.25" which is four digits, but the same mil-based would be just "3.2" or two digits. (In fact you can go out to over 1000 yards before needing more than two digits of elevation in mils.) This is less information to process. Parallax Adjustment There are two types of parallax adjustment. The first is an adjustable objective, in which the objective bell itself rotates to adjust parallax. The second is a rotating knob typically on the left side of the scope, opposite the windage knob. The adjustable objective is optically simpler, meaning fewer lenses and more clarity and brightness, but the shooter must reach forward to the objective to adjust it. The rotating knob adjustment is more convenient since it's located closer, near the rest of the turrets, however, more lenses are involved which can reduce clarity and brightness. In either case, some parallax adjustment knobs or objectives are marked for range so the shooter can dial it based on the target distance. Others are not marked with distances, and it's up to the shooter to determine visually when the image is in focus and parallax-free. To determine if parallax exists at a certain distance, the shooter aims at an object at that distance, then moves his head slightly side to side and up and down without moving the rifle. If the reticle aiming point stays "on" the object, then it is parallax-free. If the reticle aiming point moves with regard to the object, then some parallax error is present. Reticle Illumination In some low-light conditions, it is difficult or impossible to see a black reticle on a dark target. Most tactical scopes are available with the option of an illuminated reticle. Mechanically, this consists of some type of external switch or brightness adjustment control, a battery, and a light source such as an LED (light emitting diode) inside the scope actually providing the light to the reticle. Some reticles are fully illuminated, but some reticles only illuminate their center portion. A fully lit reticle can be too "busy" visually, while a partially or center lit reticle might not illuminate all the reticle features. Brightness adjustment is critical. If the reticle is too dim, it might as well not be illuminated at all. If the reticle is too bright, it will wash out and obscure the target. There are several methods to turn on or adjust the brightness. Leupold scopes have an on/off/brightness turret at the 10:30'o'clock position on the ocular housing, just to the rear of the power adjustment ring. This is offset from the elevation adjustment knob, but still obscures it somewhat. Nightforce scopes have a simple on/off switch activated by pulling put the cap of the parallax adjustment knob. Schmidt & Bender have an auxiliary knob on the side for on/off and brightness adjustment. US Optics scopes with illumination similarly have a auxiliary knob somewhere on the turret housing of the scope, location depending on other scope features. Illuminated reticles, when turned on, are visible from the front of the weapon, through the objective lens as a red/orange light. The frontal visibility depends on the angle of observation, the intensity of the reticle, and scope design. If it is critical to not be observed from the target area, then reticle illumination must not be used. (During a night shoot, shooters are visible only by their cylume chamber flags.)

Latest version always available on the WWW: http://demigod.org/optics OPTICS FOR PRACTICAL LONG RANGE RIFLE SHOOTING © Copyright 2005 Zak Smith All Rights Reserved Reproduction or Republication by express written permission only (Schmidt & Bender PMII scope with 13 mils elevation, 0.1mil clicks, on a Remington PSS rifle.) What is Practical Precision / Long Range Rifle Shooting? Practical precision rifle shooting involves engaging small and/or distant targets at the limit of weapon, ammunition, and shooter capability under time pressure in field settings. Applications include but are not limited to: very small targets 1/4"-1" at 100 to 200 yards, so-called "cold bore" shots, arbitrary unknown distance targets, shooter/spotter communication, and combinations of all of those under time constraints. Generally, these include everything a rifleman is likely to find in any "sniper", "tactical", or "field" rifle match. The typical platform is a bolt action rifle, though an autoloader of sufficient accuracy and appropriate caliber can do the job with some tradeoffs. For our purposes, consider "long range" to mean within a few hundreds yards of the load's trans-sonic boundary (the point at which the bullet slows to the speed of sound, Mach 1). For example, with typical 308 loads and rifles, we are interested in ranges from 25 yards out to about 700-1000 yards. Ballistics Background Some understanding of bullet trajectory and the physical factors affecting bullet flight is needed as background before discussing optics. In the simplest case, take an accurate rifle with sights zeroed at 100 yards shooting one type of ammunition. In the absence of wind or shooter error, the bullet will impact the point of aim (POA) when the target distance is 100 yards-- hence its "zero" is at 100 yards. The "line of aim" is a line straight from the shooter's eye, through the sighting device, to the target. The bullet starts off below the LOA by the distance between the center of the sighting device and the center of the bore. This is called the "sight over bore" distance. The axis of the bore is not parallel to the LOA-- the bore is angled slightly upwards. This causes the bullet to start off with some "upward" velocity. As it flies down-range, it rises to meet the point of aim (POA) which is where the LOA intersects with the target. Depending on the bullet's velocity, the bullet might keep rising above the LOA and again intersect with it a second time as it falls. Alternatively, it may rise just enough to meet the LOA and then start to fall again. In this graph, two loads are displayed. The green trajectory is a 308 load zeroed at 100 yards. It starts 2" low, rises to the LOA at 100 yards, and then drops off, ending around 11.5" low at 300 yards. The red trajectory is the same load zeroed at 200 yards. It starts 2" low, intersects with the LOA the first time at about 40 yards. At 120 yards, it's about 1.6" above the LOA, then drops, intersecting the LOA again at 200 yards. This is the second, or primary, zero. At 300 yards, it's about 7" low. Looking at the graph with the 200 yard zero, the point of impact (POI) at 100 yards would be about 1.6" above the point of aim (POA). At 240, the POI will be 2" below the POA. At 300, the POI will be 7.5" below the POA. Thus, to hit a small target at 300 yards, the shooter would have to hold 7" above the target. The bullet continues to fall relative to the line of aim as target range is increased. A table can be constructed which relates the drop distance for every range out to the maximum engagement range. An abbreviated table might look like this, for a rifle with a 100 yard zero. (An actual table would have intermediate distances like 120, 140, etc.) RANGE DROP 100 0" 200 2.87" 300 11.2" 400 25.6" 500 46.9" 600 76.0" 700 114.9" 800 161.7" This is helpful, but the shooter is left with the problem of how to aim 47" higher than the target when the distance is 500 yards. There won't be a 47" yardstick sticking out above the target. Aiming the cross-hairs at a point imagined to be 47" above the target is difficult and very error prone. Angular measurements Instead of measuring hold-over in terms of linear distance (inches or cm), it would be helpful to translate those linear distances into units of angular measure. The concept of angular measure is that an angle of 1 degree demarcates 1.7 yards at 100 yards, or 3.5 yards at 200 yards. Everyone with a basic understanding of geometry should understand how angles work. There are two units of angular measurement commonly used in rifle scopes. The first is the "minute of angle." Dividing a circle into 360 degrees, then each degree contains 60 minutes. One MOA demarcates 1.0472" per 100 yards of distance. The second is the "mil". One mil is one part transverse per 1000 parts distance. In units we understand, 1 mil is 3.6" per 100 yards (ie, 100 yards is 3600", one thousandth of which is 3.6"). Consequently it's also 1 yard at 1000 yards. Alternatively, in metric, 1 mil is 10cm per 100 meters, or 1m at 1000 meters. Wind Just like the atmosphere pushes on the bullet as it moves forward, slowing it down, any winds present in the bullet's path can affect its trajectory. The most common effect is the cross wind. A 10mph cross wind will move a typical 308 bullet about 6" at 300 yards. The following graph demonstrates the wind deflection as range increases for a left or right 10mph wind. Just like the drop table, we can generate a wind table, which might look something like this: RANGE DRIFT for 10mph cross 100 0.6" 200 2.6" 300 6.0" 400 11.0" 500 17.8" 600 26.5" 700 37.5" 800 50.9" Lead For moving targets, the shooter must aim in front of the target a distance which depends on the target distance and speed. This is called "lead." We'll generate a table for some standard target speed and add it to our table. Both the "drift" and "drop" values in the tables can be translated to use angular measurements (MOA or mils) instead of linear measurements (inches or cm) to aid utility. Typical Data Card The shooter might end up with a data card that looks something like this. The first line describes the load so he can keep straight what the data-card describes. The second line reminds him what each column means. 155 LAP: 2825fps 100yd 0' RANGE elev wind 4mph->(MOA) 25 4.00 0.25 6 moa 50 0.75 0.25 6 moa 75 0.00 0.50 6 moa 100 0.00 0.50 6 moa 125 0.25 0.75 6 moa 150 0.50 1.00 6 moa 175 1.00 1.00 6 moa 200 1.50 1.25 7 moa 225 2.00 1.50 7 moa 250 2.50 1.50 7 moa 275 3.00 1.75 7 moa 300 3.75 2.00 7 moa 325 4.25 2.00 7 moa 350 5.00 2.25 7 moa 375 5.75 2.50 7 moa 400 6.50 2.50 7 moa 425 7.25 2.75 7 moa 450 8.00 3.00 7 moa 475 8.75 3.25 7 moa 500 9.50 3.50 7 moa 525 10.25 3.50 7 moa 550 11.25 3.75 7 moa 575 12.00 4.00 7 moa 600 13.00 4.25 8 moa 625 13.75 4.50 8 moa 650 14.75 4.75 8 moa 675 15.75 5.00 8 moa 700 16.75 5.00 8 moa 725 17.75 5.25 8 moa 750 18.75 5.50 8 moa 775 20.00 5.75 8 moa 800 21.00 6.00 8 moa Columns: 1. Range 2. elevation for #1's target distance, in MOA 3. wind for #1's target distance, in MOA 4. lead for #1's target distance, in MOA for a target traveling at 4mph (a medium walking pace) All the trajectory values can be calculated using one of the modern small-arms ballistics calculator programs, such as Sierra Ballistic Explorer, Exbal, QuickTarget, Agtrans, etc. Several parameters are critical to their accuracy: (1) bullet ballistic coefficient (BC) values, (2) accurate measured muzzle velocity from a chronograph, (3) solid zero distance, and (4) accurate environmental conditions including station pressure, temperature, or density altitude. Data Confirmation by Shooting It is important to verify computed data by actually shooting targets at various distances and looking at the actual hits (or misses) to determine if the elevation values are correct. Shooting known-distance targets every 100 yards out to the maximum range is a good way to do this. Desired Sighting System Capabilities Let's look at the things we want to accomplish with the rifle sighting system: 1. Precisely specify drop hold-over out to our maximum engagement distance. 2. Precisely specify wind drift out to our maximum engagement distance. 3. Precisely specify target lead for moving targets/shooter. 4. Range targets of known size when Laser Range-finders are not appropriate 5. Observe target area 6. Retain #1-5's capabilities in low light conditions Optical Considerations Magnified rifle optics have several salient optical properties which we need to understand before discussing the capability trade-offs later: Parallax Error Parallax is the error in apparent POA vs. actual POA due to misalignment of the shooter's eye vs. the scope's axis. A scope can be set to be parallax error free at one distance. A scope either has adjustable or fixed parallax. Fixed parallax means the distance at which there is no error is fixed to something like 100 or 200 yards from the factory. Most tactical scopes have adjustable parallax, which means the user can adjust the parallax error free distance on the fly to reduce parallax error whatever the current target's distance. First Focal Plane vs. Second Focal Plane Definition Variable-magnification optics can have a first focal plane (FFP) or second focal plane (SFP) reticle configuration. A first-focal (FFP) reticle's features always demarcate the same angular measurement regardless of the scope magnification setting. The reticle will appear to "shrink" and "grow" with the target area as the magnification is adjusted. A second focal plane (SFP) reticle demarcates angular distance that depends on the scope magnification setting. The reticle appears to stay constant as the target area shrinks and grows as the magnification is adjusted. A fixed power optic is FFP by definition.

For MOR, you need detachable mags. Capacity of >= 10 helps. Dialing elevation for each target or each target array is slow. If using a conventional scope, dial the elevation for the most common distance and then figure out the hold overs/unders for the rest of the targets. The Horus makes this easier.

Ok, ok, I'll get around to registering!

The 70gr VLD has a BC almost the same as the 75gr Hornady, so it'll be very close.

I think so. Most of us are switching back to 9x19mm this year just so we have to carry less weight.

Yes, bring more ammo. You should be safe with a case of carbine & pistol ammo, and 400 bolt rifle rounds. Last year I think we shot less than 250 rifle?? I plan on bringing about 120 per stage for the bolt rifle, more depending on the stage briefing. Based on DL's rifle, I doubt you'll need shooting sticks. 9x is probably technically enough, but 10-15x helps. Unless you want to camp, stay in town. It's still 40-50 minutes away from the ranges.

The Robin Hood and the Colt are both cheap and servicable.

MSTN QC comp in 6.8. Various sources for 20" barrels. Not sure if that will make Major-- Paul? As a side note, I have no problem activating flashers or pushing LaRues over at 400 with 75gr 223.

Even if the program is threaded, it is not easy to make a program actually take advantage of the full processing power. Unless the task is embarassingly parallel, interprocess communication (IPC) takes overhead. And unless the computation is pretty pathologically simple yet long, memory bandwidth will end up a limiter. (I have a MSEE in computer architecture and have worked in a CPU R&D lab since 1999, for HP and now for Intel.)

ITRC = Int'l Tac'l Rifle-- Championship In any case, yes, there are a bunch of us here who head up and shoot it. If you've read my 2004 report, that should reasonably prepare you. Bring extra ammo and guns that work. Make sure your carbine shooter can make hits out to about 400 yards, and your rifle shooter to about 750. -z

I do not recommend 3N37 for light (ie, under nuclear) 9x19 loads. I found that the powder did not burn completely and left granules everywhere.

I recommend against shooting MGM if this drives you crazy. I seem to remember yelling something like while shooting at the aforementioned match.

I bought one of these for my father a couple years ago. Worksmanship and "class" is exceptional.

Is the guy who has spent 10 seconds banging away on a different stage's target or an oil drum in contention for a stage win? Is this any different from coaching a new shooter who forgot to look around a barrel to engage the last target?

It's not prohibited...

Hmmm. I might be off by 0.02. I don't remember where I got the 0.324 number, but googling around gave me two sources at .302 or .301. If so, the difference is 0.5" wind and 0.25" drop @ 300 yards.

Better not tell all those barrels that shoot XM193, Black Hills 50gr, or 50-60gr handloads into 1" or less. Woops. Here's drop/wind data for some common 223 loads _Bullet_ _BC_ _MV_ 0 50 100 150 200 250 300 | YARDS 223 M855 0.324 3150 > -2.60 -0.82 0.00 -0.25 -1.66 -4.38 -8.53 | drop (inches) 223 XM193 0.243 3270 > -2.60 -0.84 0.00 -0.21 -1.62 -4.40 -8.76 | drop (inches) 223 77SMK 0.362 2750 > -2.60 -0.67 0.00 -0.71 -2.93 -6.81 -12.52 | drop (inches) 223 77SMK 0.362 2660 > -2.60 -0.63 -0.00 -0.85 -3.32 -7.58 -13.81 | drop (inches) 223 75HOR 0.395 2660 > -2.60 -0.63 -0.00 -0.82 -3.23 -7.36 -13.39 | drop (inches) 223 75HOR 0.395 2750 > -2.60 -0.68 0.00 -0.68 -2.84 -6.61 -12.13 | drop (inches) 223 69SMK 0.305 2700 > -2.60 -0.64 -0.00 -0.85 -3.35 -7.72 -14.18 | drop (inches) 223 69SMK 0.305 2800 > -2.60 -0.68 0.00 -0.69 -2.92 -6.86 -12.73 | drop (inches) 223 M855 0.324 3150 > 0.00 0.20 0.83 1.90 3.45 5.52 8.14 | wind (inches) 223 XM193 0.243 3270 > 0.00 0.26 1.06 2.46 4.51 7.28 10.83 | wind (inches) 223 77SMK 0.362 2750 > 0.00 0.22 0.88 2.03 3.70 5.92 8.73 | wind (inches) 223 77SMK 0.362 2660 > 0.00 0.23 0.93 2.14 3.89 6.22 9.18 | wind (inches) 223 75HOR 0.395 2660 > 0.00 0.21 0.85 1.95 3.53 5.64 8.31 | wind (inches) 223 75HOR 0.395 2750 > 0.00 0.20 0.81 1.85 3.36 5.37 7.90 | wind (inches) 223 69SMK 0.305 2700 > 0.00 0.26 1.09 2.51 4.59 7.38 10.95 | wind (inches) 223 69SMK 0.305 2800 > 0.00 0.25 1.03 2.38 4.35 6.99 10.36 | wind (inches)

Other good forums-- http://www.long-range.com http://www.nationalmatch.us/ http://www.snipershide.com/ubb/ultimatebb.php http://snipersparadise.com/sniperchat/index.php