3 Gun Optic

[Onagoth]

What do you guys think? I presently have an XTR and I really like it, but with handloads and ballistic variations, the bullet drop marks are meaningless or inaccurate.

The XTR is zeroed for 62gr bullets pushing 3100 if I remember right, but the bullet drop on a 55gr pushing 2900 isn't even close at 300y, nor would it be for a 69gr bullet.

I really like the idea of an MOA or MRAD reticle, this way I can just map out where all my bullet drops or holdovers are and keep a chart in my range bag.

What do you guys think?

[RiggerJJ]

Get a load and stick with it, learn the holds from the BDC. ie; I know my 400 + 500 yd holds are to put the correct line on the top edge of the target with my XTR.

jj

[MstngLX50]

I really like the idea of an MOA or MRAD reticle, this way I can just map out where all my bullet drops or holdovers are and keep a chart in my range bag.

Couldn't agree more. I use a mil reticle and a PDA running Horus Atrag. With planning you can use one of the free online calculators to print out something close enough for 3-gun. With any load at any elevation I know where to hold, I don't necessarily do it right but that's a training issue...

Another thing to consider with either ballistic, mil, moa etc...is the focal plane. If it's not a first focal plane scope then the reticle only works at max power.

I just got a Bushnell 1-6.5 with the BTR-2 mil reticle and it is by far my favorite scope. It's replacing a short dot, and I'm ordering another that's how much I like it. First focal plane, mil reticle, mil adjustments, low profile scope caps, daylight illumination. Best scope I've found so far for 3-gun.

[Onagoth]

I really like the idea of an MOA or MRAD reticle, this way I can just map out where all my bullet drops or holdovers are and keep a chart in my range bag.

Couldn't agree more. I use a mil reticle and a PDA running Horus Atrag. With planning you can use one of the free online calculators to print out something close enough for 3-gun. With any load at any elevation I know where to hold, I don't necessarily do it right but that's a training issue...

Another thing to consider with either ballistic, mil, moa etc...is the focal plane. If it's not a first focal plane scope then the reticle only works at max power.

I just got a Bushnell 1-6.5 with the BTR-2 mil reticle and it is by far my favorite scope. It's replacing a short dot, and I'm ordering another that's how much I like it. First focal plane, mil reticle, mil adjustments, low profile scope caps, daylight illumination. Best scope I've found so far for 3-gun.

That is a nice reticle

Edited May 1, 2012 by Onagoth

[gdboytyler]

Now that I've learned how to use the MRAD reticle on my SWFA 1-4X, I won't buy a scope unless it has a similar reticle. Switch out the loads, chrono the load and plug it into a ballistic calculator for your drops.

I didn't like the BDC reticles because the graduations looked too far apart.

[Onagoth]

anyone got a picture of the actual reticle (looking through the scope) The images online are always hard to tell the size of it.

[djeffers]

What do you guys think? I presently have an XTR and I really like it, but with handloads and ballistic variations, the bullet drop marks are meaningless or inaccurate.

The XTR is zeroed for 62gr bullets pushing 3100 if I remember right, but the bullet drop on a 55gr pushing 2900 isn't even close at 300y, nor would it be for a 69gr bullet.

I really like the idea of an MOA or MRAD reticle, this way I can just map out where all my bullet drops or holdovers are and keep a chart in my range bag.

What do you guys think?

I haven't had a problem with mine. Believe it or not, but my 55's and 69's were hitting the same place at 200. The only difference I noticed with my loads, barrel, etc. was that my 69's were on the money and my 55's were high (added @ 300). But, I guess it depends on what you mean by close as I was shooting a paper plate, and if you are shooting for groups...that might explain it.

Edited May 2, 2012 by djeffers

[Onagoth]

My factory 55gr ammo was pushing 2900 ft/sec, which I knew wouldn't line up with the 300y hash mark exactly, but it wasn't even close.

in fact, I had to use the 400y hash mark to hit a gong at 300y.

[Hi-Power Jack]

the bullet drop marks are meaningless The XTR is zeroed for 62gr bullets pushing 3100 , but the bullet drop on a 55gr pushing 2900 isn't even close at 300y, nor would it be for a 69gr bullet.

I'm just getting into rifle shooting - silly question, but

how large are the 300, 400 & 500 yard targets? How close

do we have to be to hit them?

Are we talking about USPSA targets at those distances?

[Onagoth]

I'm not sure, I just got into this a little while ago. I think at distances beyond 300y the targets would be fairly large, but my accuracy goal is always 2 MOA.

So, I strive to hit a 10-12" plate at 500 yards.

[gdboytyler]

1335897883[/url]' post='1695198']

I'm not sure, I just got into this a little while ago. I think at distances beyond 300y the targets would be fairly large, but my accuracy goal is always 2 MOA.

So, I strive to hit a 10-12" plate at 500 yards.

It would vary by each match, but at the Pala 3-gun matches in So Cal, the shorter distances, 100-200ish are 8 inch plates, 200-325ish are 12 inch and if we shoot at 400 or so we have a full size ISPC steel target.

[Nuke8401]

What you could do:

- Load the 69's to match your BDC within a few inches out to say 400 - 500 yards.

- Then load your 55's to match your POA at say 200.

You will hear the goal/normal target size is 4 MOA minimum (16" at 400yds, 20" at 500) at many 3 gun matches.

You should be able to match the 62gr ballistics closely with your 69's, and use them for 0 - 400,500 yards.

Use the 55s for short range stuff.

The 55s may be a little light to make minor PF when loaded to POA at 200 matching the 69s.

Do you know the actual MOA values for the XTR?, don't just run a ballistic calc for a 62 at X FPS. You need the MOA numbers for the BDC.

Leupold CMR-2 is based on the M855(62gr) but the BDC MOA markings don't come close to the data you get when you use a ballistic calculator.

David E.

[bikerburgess]

I'm just getting into rifle shooting - silly question, but

how large are the 300, 400 & 500 yard targets? How close

do we have to be to hit them?

Are we talking about USPSA targets at those distances?

I haven't been at it to long either, but at the Multigun Nationals the shots were all 4moa or larger (8" plates at about 185yd and a couple of Larues at 385yd) a local match had a 4" plate at 160yd so about 2.5moa,

and to hit them you just need to hit them, the long range stuff is normally steel so nobody has to go score it after each shooter.

Mike

[Onagoth]

What you could do:

- Load the 69's to match your BDC within a few inches out to say 400 - 500 yards.

- Then load your 55's to match your POA at say 200.

You will hear the goal/normal target size is 4 MOA minimum (16" at 400yds, 20" at 500) at many 3 gun matches.

You should be able to match the 62gr ballistics closely with your 69's, and use them for 0 - 400,500 yards.

Use the 55s for short range stuff.

The 55s may be a little light to make minor PF when loaded to POA at 200 matching the 69s.

Do you know the actual MOA values for the XTR?, don't just run a ballistic calc for a 62 at X FPS. You need the MOA numbers for the BDC.

Leupold CMR-2 is based on the M855(62gr) but the BDC MOA markings don't come close to the data you get when you use a ballistic calculator.

David E.

I hear ya, but it still makes no sense. The 400y hash mark represents a correction of 35" with a 100y zero. It seems impossible to me that factory 55gr ammo pushing 2900 ft/sec from the muzzle would drop that much in 300y. This is going through a 1:8 18" barrel if that matters. I also verified the 100y zero on my rifle.

[michael1778]

I may be a new 3-gun shooter, but I've been an engineer for 20 years (oh man I feel old now). Let me show some calculations on the bullet drops. I will use this URL for the ugly computations that integrate the effects of drag over time: http://www.jbmballis...jbmtraj-5.1.cgi

For the tool's output, we see that the time from leaving the muzzle to arriving at 400 yards down range is 0.567 seconds. That is using a Hornady 55gr FMJ leaving the muzzle at 2900 ft/sec. Cool, now we can totally ignore the other motion of the bullet and only consider its drop.

The distance an object travels falling without any drag or other retarding force (we ignore that for this simple estimate) would be (1/2)*(acceleration due to gravity)*(falling time )^2. You might recognize that from high school physics as 1/2*a*t^2 or 1/2*g*t^2. This assumes no initial downward velocity.

Acceleration due to gravity at sea level is about 32.2 ft/sec^2. So, we substitute and get:

(1/2)*(32.2ft/sec^2)*(0.567sec)^2)

= 0.5 * 32.2 ft/sec^2 * 0.321 sec^2

= 5.17 ft

= 5.17ft * 12in/ft

= 62 inches

Now, since the bullet is not traveling perfectly parallel to the local horizon at firing it goes up at first. In other words, it's initial velocity has some vertical component in the positive (up) direction that has to be overcome by the downward gravity falling component. Bullet paths are actually flat arcs that eventually drop in on the target at long range. We aren't firing lasers here (darn it). Also, we did ignore drag as it falls, so that would come into play in the real world.

Anyway, you can see that we get into the same order of magnitude ignoring these more effects of the bullet's initial flight direction.

A less mathematical way to convince yourself is this. Drop a pebble from about 3 or 4 feet up and see how long it takes to fall. You'll see the falling time is on the same magnitude as the calculated bullet flight times out to 400 and 500 yards.

I hope this helps you feel more comfortable about the physical principles involved with long range rifle shots.

Now if only all this would help me actually hit something that far out!!!

Edited May 1, 2012 by michael1778

[Nuke8401]

I hear ya, but it still makes no sense. The 400y hash mark represents a correction of 35" with a 100y zero. It seems impossible to me that factory 55gr ammo pushing 2900 ft/sec from the muzzle would drop that much in 300y. This is going through a 1:8 18" barrel if that matters. I also verified the 100y zero on my rifle.

Running it through the simple Hornady BC http://www.hornady.com/ballistics-resource/ballistics-calculator

55gr, BC=.243, 2.6" sight height, 100 yd zero, 2900 FPS gives you 33.5" drop at 400 yards with a 100 zero. So the 35" you have is right on.

WIth that scope I would use a 200 POA/POI zero (at the 200yd mark on the reticle) and you would be good to 500 at least.

The 100 yd would be plenty close as would be the 300 and 500 marks.

David E.

Edited May 1, 2012 by Nuke8401

[Onagoth]

Either I didn't explain it right, or you guys misunderstood, probably the former.

What I am saying is I have to use the 400y bullet drop hash mark when shooting at 300y. I wasn't shooting at 400y, I was shooting at 300y, yet with a 100 yard zero I was still required to holdover by around 35" to get hits on the gong.

Either the ballistics information I have used is wrong, or the scope reticle is out somehow, presently it is beyond my understanding. I know there will be small differences between the cartridge I was shooting and the one the reticle is based on, but it shouldn't be that much.

For what its worth, the cartridge is AE223 with a muzzle velocity of 2900 ft/sec and a BC of 0.265.

Edited May 2, 2012 by Onagoth

[CJW]

What I am saying is I have to use the 400y bullet drop hash mark when shooting at 300y. I wasn't shooting at 400y, I was shooting at 300y, yet with a 100 yard zero I was still required to holdover by around 35" to get hits on the gong.

My guess is your BDC assumes a 200yd zero, not a 100yd zero. If that's the case, then of course the stadia wouldn't match up to actual shooting distances.

[Onagoth]

Sadly, it does not. It assumes a 100y zero.

[gdboytyler]

1335916928[/url]' post='1695448']

What I am saying is I have to use the 400y bullet drop hash mark when shooting at 300y. I wasn't shooting at 400y, I was shooting at 300y, yet with a 100 yard zero I was still required to holdover by around 35" to get hits on the gong.

To have the drops that far off, I'd have to guess one of the following:1. Your 100 yd zero is off. Or your 400yd distance is wrong. Did you measure distances with a range finder or step it off?2. Your scope is NOT 2.6" above your bore3. You had some weird atmospheric conditions

[Onagoth]

Definitely not the zero....I checked that and shot a 1.2" group right on the dot.

The differences between the reticle and what I am shooting are as follows:

Reticle

weight 62gr

Sight height 2.3"

muzzle 3025 ft/sec

BC 0.307

Zero 100y

The reticle has 10 hash marks representing bullet drops from 200y to 1000y in 100y increments. With this setup, the bullet drop for 300y is 10.3" and 25.4" for 400y.

My load/setup

weight 55gr

Sight height 2.75"

muzzle 2900 ft/sec

BC 0.269

Zero 100y

Bullet drops for this load are esimated to be 11.5" at 300y and 29" at 400y.

I have run a million scenarios accounting for the difference, but none of them compare to my actual results. The actual results are that I have to use the 400y hash mark for accurate shooting at 300y, which is representative of between 24" and 29" of bullet drop.

The only thing I can think left to do is shoot POA at 300y and physically measure the bullet drop. I suspect is will be around the 10-12" that it should be with a 100y zero, but then I will be left figuring out why that doesn't even come close to the reticle design.

I've read a lot of threads on this scope and everyone seems to say that the bullet drop marks line up pretty well with the loads they are running, but not for me apparently.

Edited May 2, 2012 by Onagoth

[sarpau]

Hey Matt,

its Paul

Is EESA in yards or meters?

300m = about 330yards.

Not that this would totally account for what you are experiencing, but it would make up some of the variance.

[HRider]

Try having someone else shoot your rifle and see if they get the same results. I used to get a different POI with the same hold (iron sights) between shooting from bags and shooting prone. My head position was different, so I was looking through a different part of my eyeglasses, and perhaps was not holding the rifle as tight.

Hurley

[waktasz]

The dots don't really mean anything since as you can see they only match up to one load. If you can calculate (and then test at the range) your actual bullet drop and note it properly it doesn't matter what distance the dots are set up for.

For example, with my load, this the yellow crosshair represents my hold for a 300 yard target. The numbers on the reticle are supposed to be 300, 400, 500 and 600 but they aren't...I'm not worried.

[Onagoth]

Hey Matt,

its Paul

Is EESA in yards or meters?

300m = about 330yards.

Not that this would totally account for what you are experiencing, but it would make up some of the variance.

Its in meters, which I figure would account for maybe a couple inches. Although the 330 vs 300 is a big gap, my zero is also at 100m which mitigates the difference somewhat.

The dots don't really mean anything since as you can see they only match up to one load. If you can calculate (and then test at the range) your actual bullet drop and note it properly it doesn't matter what distance the dots are set up for.

For example, with my load, this the yellow crosshair represents my hold for a 300 yard target. The numbers on the reticle are supposed to be 300, 400, 500 and 600 but they aren't...I'm not worried.

I understand that part, but they aren't even close. If your 400y dot was your actual 300y hold, would you be worried then?

On a separate note, is the POA on your calculator accurate for the load data you put in? I know these are perfect, but the POA in Strelok is consistent with the hash marks, it just doesn't resemble reality.

Edited May 2, 2012 by Onagoth