Zero/holdover

[outerlimits]

here's the deal-i luv my accupoint, unless i have to holdover on a longer target-it's tricky, slow and a pain to do right. so i'm curious what options i have when presented with a stage that has long distance targets (i.e. 300-400 yds).

obviously i could just dial in a scope adjustment for that stage, which i really do NOT want to do. the other obvious thing is change the zero for my setup. i've always zeroed my AR at 200 yds, which is great until i'm dealing with a bullet drop of 12+ inches. having to holdover on a 10" plate with those damn black posts under the triangle sux. so i'm considering zero at 250+ if i know there is a stage in the match that is 350-400.

oh yea, the other option is a TA-11, but i really like the 1.25 end on the accupoint.

any thoughts?

[tewlman]

here's the deal-i luv my accupoint, unless i have to holdover on a longer target-it's tricky, slow and a pain to do right. so i'm curious what options i have when presented with a stage that has long distance targets (i.e. 300-400 yds).

obviously i could just dial in a scope adjustment for that stage, which i really do NOT want to do. the other obvious thing is change the zero for my setup. i've always zeroed my AR at 200 yds, which is great until i'm dealing with a bullet drop of 12+ inches. having to holdover on a 10" plate with those damn black posts under the triangle sux. so i'm considering zero at 250+ if i know there is a stage in the match that is 350-400.

oh yea, the other option is a TA-11, but i really like the 1.25 end on the accupoint.

any thoughts?

just a few!

sell that damn accupoint and buy the afore mentioned ta-11. then buy the progressive machine scope cover for the ta-11. Then and only then will you have a truely awesome 3 gun setup.

this of course being a deliberate jab at my friends who use the accupoint!

[PacMan]

...i'm considering zero at 250+ if i know there is a stage in the match that is 350-400.

any thoughts?

All of my optics are zeroed at 250, including the TR21. Using 55 gr. at 3100-3200 fps, the 250 zero give me a +1.8" from 100 to 200 yds and - 3" at 300 yds and -16" at 400 yds. Workable with TR21 out to 350 yds, then it becomes a crap shoot

[MikeFoley]

Mounted 2.5 inches bore axis to scope axis, my Accupoint is point of aim=point of impact out to 300 yards. I didn't find holdover a big issue on 400, 500, 600 the one time I shot those distances. Certainly the scope could be improved with a set of long distance crosshairs like the other Trijicon scopes, but can't be done with the current method of manufacturing the reticle. If they made a 1-4 variable with a triangle reticle and long distance crosshairs I would buy one, but I don't care for fixed power/occluded or the donut reticle used by most. It boils down to personal preference, and spending some time with the scope IMO.

My barrel is 18 inches, and I have zeroed at 50 yards if that helps.

[George]

Butch, if you are shooting 55gr ball, then the 250 zero that Pacman uses is fine and dandy. I would not however zero heavy .223 projectiles (69-77 grain) beyond 200 because of the trajectory parabola hump at closer distances.

[kurtm]

Okay I'll buck the system. I run a 300 yd zero on just about everything. I even did it with the TA-21 while I still had it befor I sold it to my brother, ( it didn't do anything that the TA-11 didn't do for me). It worked just fine! 3" high at 100, 4" high at 200 and right on aT 300. then just put the diamond at the top of anything at 400. It worked for me. KURT

[Paule]

I like to zero the tip of the triangle at 300 yards. Close zero is around 38 yards. 3" high at 100, 2" high at 200, on at 300, and 3" low at 400. For plates, just hold on at 0-400. For paper at 50-100 I always hold middle A-zone and hold on the neck for head shots. Simple for me and hits are consistent.

Edited October 26, 2005 by Paule

[outerlimits]

I like to zero the tip of the triangle at 300 yards. Close zero is around 38 yards. 3" high at 100, 2" high at 200, on at 300, and 3" low at 400. For plates, just hold on at 0-400. For paper at 50-100 I always hold middle A-zone and hold on the neck for head shots. Simple for me and hits are consistent.

paule-thanx fer the tip.

dunno what ammo yer throwing downrange, but the trajectory tables with my ammo zeroed at 300 puts it low by about 10" at 400. still, it's mo betta than holding over the top of the flasher!

[George]

Ditto on the larger drop from 300 to 400 yards.

I just ran a trajectory chart on a 55gr BT at 3250 fps with a G5 corrected BC set for a 300 yard zero and the drop at 400 is 12 inches.

3" drop from 300-400, no way. That's not possible until a 55er is moving over 4500 fps!!!

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Regards,

[TommiF]

I have been using TR21 for 3 seasons and always reset my zero between 150meters and 300meters. Here in Finland most riflematches are in military areas where in no depth at all in stages. Longrange stages are always to one distance. Resetting zero is my choice and it works with TR21 perfectly.

When I shoot stages where targets are in different distances (in Norway and Denmark), I zero my TR to longest target and shoot low all targets in shorter distance.

Tommi

[Paule]

I typically shoot 77gr SMKs (Mk262 Mod1, 2800 fps at the muzzle) on longer targets, but the 3" drop at 400 was a typo. Meant to hit the "6". When I run the numbers I get more drop from the chart than I actually experience shooting targets, paper or steel. I think the reason, for me anyway, is the chevron reticle. On the closer targets, (200 or less), I see the targets very well and seem to aim more precisely, especially as to holds over/under. On longer targets, where they are harder to see in detail, I have a tendency to hold a little higher than I do with other reticles. For me, the tip of the chevron seems to blend into the target and I let it slide up a bit to get confirmation of where I'm holding. At 400, the tip is likely at or just above the top edge of the target.

[George]

Hi Paul,

I am still mystified by the 6" drop from 300-400 yards even with G1 drag data which is not correct for a Boat Tail projectile like the SMK 77.

Here is what my ballistics program gives out for the SMK 77 at 2800 fps with it's G1 BC coverted to the G5 drag model (correct drag coefficient for all boat tails):

For comparison purposes, here is a 55 gr FMJ Boat Tail at 3250 fps:

I use the Shooting Labs software from RSI and it has always been spot on at distance when I apply it's dope directly.

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Regards,

[Paule]

George,

I use RSI software too and the drop charts for sea level are the same as what I run. What I am saying is that for me, and the way I "see" the chevron reticle of a TA11 at 400 yards, holding over 15" will cause me to shoot over the top every time. I believe this is due to the difficulty I have getting the tip of the chevron to register exactly with the top edge of a plate at longer distances. At 100-200 yards, no problem. As the distances get farther out and the plates appear smaller in relation to the size of the reticle, my "top of the plate" holds tend to be on the high side. This translates in to less needed holdover for these targets. If I try to get too precise with the exact tip of the chevron, I go slower (and I'm already slow), and miss more.

I have seen other shooters who had the same experience with the chevrons, so it isn't just me. If I zero the same rifle at 300 with a NXS scope with NPR2 reticle the aiming point will be consistent with the drop charts. My wife shoots a TA31F chevron and it works the same way zeroed at 300 as my TA11. While the actual drop may be 12-15" depending on elevation and temperature, the effective holdover is half that due to what I see in relation to the targets.

[George]

Ah so desuka', now I see.

There is definitely some imprecision in the chevron and even the donut which is why I chose the TA-01 with the JP reticle. Precise as all get-out and fast too! Cake and eat it for me. But I do see why you get your results, I just wasn't sure where you were getting that incredible BC from ;-)

BTW, ya' gotta love that RSI software. I have done sightins at 200 yards at sea level and gone to 4k and 7k elevations with printouts for that L and when I applied the dope to the scope the El was spot on out to 700+ :-) G5 drag modeling for boat tail projectiles rocks the house IMO.

[Paule]

I concur on the RSI software. I use the G5 and G7 models a lot. I have checked quite a few bullets with dual chronos and their conversions are very accurate. I am also a big fan of their Pressure Trace product. I should buy stock in the strain gauge division! It also kept me from blowing myself up developing loads for the 6.8SPC a few years ago.

The 300 yard zero with a TA11 is something I only use for 3-Gun, primarily because it is easy to remember and the targets are virtually guaranteed to be 400 or (usually) less. I have another TA11F on a rifle I shoot coyotes with and it is zeroed conventionally at 100 yards. Then I just shot it at various ranges out to 600 to get valid dope for the stadia lines and it works pretty well as far as I can shoot it.

BTW, I also use the "TRAG2 on a chip" a lot for field calculations. It isn't quite as accurate as RSI, but it is close, and runs on my Treo650 phone. Since I can save multiple loads to the memory card, it is very convenient for changing conditions when in the field, travelling, etc. I usually verify in advance with RSI, but it is so close I don't worry much about using it on the fly.

[Paule]

Since this thread is pretty much confined to ACOGs and Accupoints, I thought I might share the target I developed specifically to sight in with these reticles. I have always had problems with vertical dispersion using conventional targets, owing to the imprecise nature of my use of the reticles. This target solves those problems for me when zeroing these scopes. The attached gif file will hopefully print out to scale. I did it in MS PhotoDraw, so if it doesn't scale correctly for you, email me and I can send the originals.

It should measure as follows. With the tip of the scope reticle nudged up into the white are under the chevron on the target, the top of the chevron should be 1" high. Each stadia line above that is an additional 1", so they will be, 2, 3, and 4" high. The other features of the target are more subtle. The chevron on the target is not exactly the same included angle as either the TA11F or Accupoint reticles. It is slightly wider, and for a reason. When I first shot with these I made targets exactly to fit each scope. While they worked okay, I found that I could not shoot best groups when zeroing for 250-300 yards. I always had horizontal dispersion. I found that by opening the angle up slightly on the target, I could get a little white space down each side of the chevron. As long as I had equal amounts on each side, my groups tightened up nicely. Also, I could easily see the effects of consistently canting the reticle, even slightly. Overall, it worked much better. I find that when I zero a new gun at 100, then check at 200, 300, 400, etc., I am much more "on" at the longer ranges now, with less need to fine tune windage.

Anyway, try it if you like, it may help someone...

ps. I like the medium blue for most days, but also use green for contrast on cloudy days...