Advanced Marksmanship Printing Issues Help Requested

[TacticalTeacher]

Good evening all,
I am currently running a few field tests on a weapon system and I have experienced a strange printing pattern with this rifle. The rifle specs are as follows:

Arma-Lite AR-10
Leupold Mark IV M1 6.5-20x LRT Scope with TMR Reticle
PRI Free-float Handguard with 20 MOA Top Rail
Rock Creek R5 11.5:1 20” Barrel
Custom SMTC 30mm Ring Set
Magpul 2nd Gen PRS Adjustable Stock
AAC Muzzle Break / Suppressor Attachment
AAC 762SD Suppressor

for some reason this rifle prints consistant 100m 3 round groups at or below .5 moa, but when pressed to fire a 5 round group i consistantly find the 4th or 5th round printing roughly 2 mins at 3-5 oclock. these are certainly not called fliers. This happens with the suppresor as well as without. could this possibly be caused by the break or would this be a harmonics issue? Any info is greatly appreciated as i have racked my brain on this for weeks at this point!

 

[BigBrother]

Re: Printing Issues Help Requested

Try spacing your shots out over a longer time period- say a shot every 2 minutes.

See what happens then.

 

[Suasponte]

Re: Printing Issues Help Requested

What load are you using? Is this factory ammo or reloads?

Could be heat stress on the barrel from consecutive firings!

My buddys DPMS has that same tendency.

Terry

 

[TacticalTeacher]

Re: Printing Issues Help Requested

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BigBrother</div><div class="ubbcode-body">Try spacing your shots out over a longer time period- say a shot every 2 minutes.

See what happens then. </div></div>

I have tried this in 10 min strings with a shot every 1 - 3 mins with the same results always 2 out of 5 shots impacting off zero with no called fliers.

 

[TacticalTeacher]

Re: Printing Issues Help Requested

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: suasponte</div><div class="ubbcode-body">What load are you using? Is this factory ammo or reloads?

Could be heat stress on the barrel from consecutive firings!

My buddys DPMS has that same tendency.

Terry
</div></div>

factory match 168 HPBT federal matching lot for all tests. i suppose it could just be the nature of the semi auto but i have never experienced this with my remy.

 

[Suasponte]

Re: Printing Issues Help Requested

Here is some video of sub-sonic load testing we did!
No, it does not cycle!

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Terry

 

[ChadTRG42]

Re: Printing Issues Help Requested

Are the 4th or 5th shots the last shot in the mag, or are there more rounds in the mag after these shots? If the bolt is locking back to the rear on these shots, it might cause this.

 

[TacticalTeacher]

Re: Printing Issues Help Requested

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Are the 4th or 5th shots the last shot in the mag, or are there more rounds in the mag after these shots? If the bolt is locking back to the rear on these shots, it might cause this.</div></div>

never thought of that... most mags have been loaded with 5 rounds. i will increase the amount of rounds in the mag and try again. thank you. i cant belive i never thought of that.. im new to this semi auto precision.

 

[BigBrother]

Re: Printing Issues Help Requested

I'm no gunsmith, but how would this at all affect it?

Wouldn't the bullet be out the bore by the time the gas has traveled back through the tube, cycled the action, and the bolt locked back?

 

[TacticalTeacher]

Re: Printing Issues Help Requested

Its worth a try. i am open to any suggestions at this point. im not worried about shooting tight groups as long as this thing can get the hits but i am really curious as what is causing these fliers.

 

[ChadTRG42]

Re: Printing Issues Help Requested

I'm not an AR-10 shooter, but I've seen simple things cause weird results on target with AR's. You have to drive AR's different than bolt guns. They need a very firm hold and good, consistant shooter position to shoot them well. The bolt locking back changes the recoil impulse and follow through. I would try a 5 shot group with 6 or 7 rounds in the mag, and see what that does. Maybe some veteran AR-10 shooters can chime in.

 

[BigBrother]

Re: Printing Issues Help Requested

I can't speak to AR-10s, as I've never owned one, but I have to challenge what you're saying about ARs in general. If that were endemic, you'd never see the kind of scores, behavior, and preference you see on the line in highpower matches (where fairly stock ARs rule supreme). There, you're alternately single loading (bolt's locking back there!), shooting from a 2rd mag, and an 8rd mag.

There's no real special behavior you have to consider in any of those stages, beyond whatever minute sight adjustments are needed to accommodate your different shooting positions (standing, sitting, prone).

A weapon system as finicky as you're describing would be a serious detriment to those scores on the line. If anything, the AR is the platform of choice *because* it's so ergonomic and easy to shoot.