AR Positional POI Shift Test

[LRRPF52]

Here’s the shooting footage from the above targets

Skip to 7 minutes for the shooting

For the BCM/Geissele, the only thing I can think of for that insane deviation with the bipod prone shoot was contact with the gas block with maybe the bipod mount back-end hardware. Because it went right back to close POA=POI for the tripod-supported.

Excellent video to illustrate what we’re talking about with positional POI shift though.

 

[LRRPF52]

The rifle that has me the most curious is the Hk G28, because it uses a steel upper. Would be interesting to see if it holds more true than all the aluminum uppers.

 

[Veracity]

@Veracity you're mentioned in the SOLGW article on their new L89A handguard. Have you been able to test that + a broadsword upper for shift? I can't imagine it's much different than a traditional AR.

It's not much different. Right at .25 mil in my testing of 2 rifles. 1 is 18" and 1 is a 20". Both suppressed

 

[itsallbacon]

For the BCM/Geissele, the only thing I can think of for that insane deviation with the bipod prone shoot was contact with the gas block with maybe the bipod mount back-end hardware. Because it went right back to close POA=POI for the tripod-supported.

Excellent video to illustrate what we’re talking about with positional POI shift though.

I bet you’re right. I’m going to have to try it again.

 

[Carlos0311B4]

I wasn't aware of that. I will have to search for it and check it out. That is interesting info.

2:23

 

[lennyo3034]

Tested 3 different bullets out of new barrel today and decided to try this test. Top row is prone, bottom is barricade. Unfortunately not corresponding bullets so I labeled the groups to better match.

Mega bullet upper and KAC URX4. I know other people have posted issues with URX4 in this thread but this is my second and I haven’t had issues. I actually have a spare MML upper available but chose the URX4 on standard upper because I can get a lower height over bore with URX4.

I will note on this particular rifle I bridged the upper and handguard with the scope mount. Not intentionally, I just didn’t have a cantilever available and this was unused.

 

[Ernest 5.56]

Tested 3 different bullets out of new barrel today and decided to try this test. Top row is prone, bottom is barricade. Unfortunately not corresponding bullets so I labeled the groups to better match.
View attachment 8674148


Mega bullet upper and KAC URX4. I know other people have posted issues with URX4 in this thread but this is my second and I haven’t had issues. I actually have a spare MML upper available but chose the URX4 on standard upper because I can get a lower height over bore with URX4.

I will note on this particular rifle I bridged the upper and handguard with the scope mount. Not intentionally, I just didn’t have a cantilever available and this was unused.

View attachment 8674149

What barrel ?

 

[lennyo3034]

Bartlien either from Craddock or WOP. Been lying around for years and decided to do something with it.

 

[black5.3]

Im kinda battling with this issue right now and im leaning toward it being a fundamentals-consistency issue while shooting my rig from prone with bipod far forward and rear bag. All my groups are around 1”-1.25” and in that group I will have 3-4 rounds stacked in a .5”-.6” group and then a couple shots that blow the group out to a inch or a little more…

Rifle is a vltor Mur upper receiver, PVA Osprey 6 arc barrel, Geissele mk18 rail(bipod attached via arca on the rail), suppressed with TBAC Ultra 7 .264.

I admit I don’t have nearly as much time trying to shoot ar’s at a level of precision like i do my bolt guns and thats why im thinking its definitely me and not the gun or load(i am handloading for this gun). Barrel has right at 200 rounds on it so it should be broke in.

This is not always how it shoots but is kind of representative of how i can lay down some great groups and then the next is over an inch. Those smaller dots are right at 3/4”, the grid paper im shooting on is a weird scale.

 

[vegashelipilot]

Here's another data point.

Rifle: Cobalt Kinetics CK-Pro with Rainier Match 16" barrel

Test (Left to Right)
bipod near muzzle > bipod near magwell > no bipod, shot off bag near magwell

*ignore terrible group sizes, shot cheap practice ammo fairly quickly on these groups

Results:
Appears to be about a 0.2 mrad shift for positional shooting. I probably should have tested this a long time ago. Good to know.

 

[tyrider427]

I definitely need to do more testing, but reading this thread got me curious. I shot my LMT MRP tonight from a bag and also from a bipod extended all the way out on the rail. I did get two nice tight groups, but with a bipod the group dropped .1 mil and shifted .1 mil left.

Barrel is a Bartlein conversion, it's now a very accurate rifle. I went with LMT partially because of the minimal POI shift, along with the ability to change barrels quickly and easily.

I'll test this more this weekend and follow up with some photos

How do you change barrels easily? I was aware of that feature but was under the impression that you have their own proprietary barrels?
And that wasn't the case for stand-alone handrails/receivers sold separately?

 

[tyrider427]

Here's another data point.

Rifle: Cobalt Kinetics CK-Pro with Rainier Match 16" barrel

View attachment 8680139

Test (Left to Right)
bipod near muzzle > bipod near magwell > no bipod, shot off bag near magwell

*ignore terrible group sizes, shot cheap practice ammo fairly quickly on these groups

View attachment 8680140

Results:
Appears to be about a 0.2 mrad shift for positional shooting. I probably should have tested this a long time ago. Good to know.

I thought making composites to see how these would be expressed as 15 round groups would be interesting.View attachment 8651892View attachment 8651893View attachment 8651894View attachment 8651895View attachment 8651896View attachment 8651897View attachment 8651898View attachment 8651899View attachment 8651900View attachment 8651901View attachment 8651902View attachment 8651904

Awesome write up! Seriously this rocks. Which SOLGW were you using?

 

[matt33]

How do you change barrels easily? I was aware of that feature but was under the impression that you have their own proprietary barrels?
And that wasn't the case for stand-alone handrails/receivers sold separately?

I have two different Factory LMT barrels, but a gunsmith named D Wilson can convert virtually any standard AR-15 Barrel to work with the LMT quick change barrel system

I had him convert a 16" Bartlein barrel a few months ago, it is an absolute tack driver now, Factory LMT barrels in 5.56 have been mediocre at best for me in terms of accuracy.

I really like LMT, the monolithic upper rail is my favorite upper on the market, and their Ambi lower is my favorite lower on the market, I just wish they were more accurate as they come from the factory