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

 

[JR1200W3]

Seekins SP-10 builders kit. Mullerworks custom 6.5CM barrel. JP guts.

One bag, one tripod, one bipod, one barricade. About a .1mrad from all other positions to tripod and back. And I'm fairly certain it's how I'm driving the gun off the tripod to manage wobble that's causing the shift, not the handguard flexing.

 

[DeathBeforeDismount]

What brass catcher are you using?

 

[JR1200W3]

Tactical Brass Recovery AR15/AR10/SCAR 16 Brass Catcher - Operator MID (Color: Multicam BLACK)

OPMID

 

[Wormydog1724]

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.

I have wondered about bridging my upper/rail with a low YHM riser and seeing if that would help stiffen the system and reduce the POI shift I've seen.

Or if they were still available, something like a Swan Sleeve.

I might mess with that this weekend.

 

[BurtG]

Yes speaking of has anyone tested mk12s with the PRI tube ?

 

[taisenki]

Yes speaking of has anyone tested mk12s with the PRI tube ?View attachment 8691536

 

[WeR0206]

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. View attachment 8675382View attachment 8675383This 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.

Nice…I have almost an identical build that I just finished (MUR upper + 18” Osprey 6 ARC barrel + M89 15” Rail). I have yet to shoot it as im still working on some ammo with alpha brass and 107 smk’s.

 

[black5.3]

Nice…I have almost an identical build that I just finished (MUR upper + 18” Osprey 6 ARC barrel + M89 15” Rail). I have yet to shoot it as im still working on some ammo with alpha brass and 107 smk’s.

View attachment 8706494

Post what kind of results you are getting. I have only heard good things about the M89 rail. One thing i have started doing is incrementally placing the bipod closer to the receivers instead of all the way out toward the muzzle on the rail. I can only image there is more influence on the rail because of the increased leverage on the rail when the bipod is all the way toward the muzzle. I moved it back toward the receivers about 4-5” and noticed a little better consistency. I have much more work to do with my form and shooting gas guns.

 

[WeR0206]

Post what kind of results you are getting. I have only heard good things about the M89 rail. One thing i have started doing is incrementally placing the bipod closer to the receivers instead of all the way out toward the muzzle on the rail. I can only image there is more influence on the rail because of the increased leverage on the rail when the bipod is all the way toward the muzzle. I moved it back toward the receivers about 4-5” and noticed a little better consistency. I have much more work to do with my form and shooting gas guns.

Im almost done with the ammo so I will prob get to the range within the next few days and will post results. Note this barrel still has to break in so Im not going to scrutinize group size too much yet. I just want the gun to cycle properly during this first trip out

 

[black5.3]

Im almost done with the ammo so I will prob get to the range within the next few days and will post results. Note this barrel still has to break in so Im not going to scrutinize group size too much yet. I just want the gun to cycle properly during this first trip out

Good deal, I have about 250-260 rounds on this barrel now so it’s as broke in as much as it will get by now.

 

[WeR0206]

Good deal, I have about 250-260 rounds on this barrel now so it’s as broke in as much as it will get by now.

Ugh. Had the ammo all loaded up and ready to go on Friday night. Since I’m using new Alpha brass I incorrectly assumed I wouldn’t need to do any kind of shoulder bump and only have to chamfer/deburr and put some dry lube on the neck for bullet seating. Luckily before heading to the range this weekend I decided to test a piece of unloaded new brass to see how easily it chambered And I couldn’t really get it to chamber at all. It was way too tight (had to mortar to get it out). I had to end up bumping the shoulder back about 4 thou in order to get it to chamber and unlock easily. I hope to finish the ammo tonight and get to the range within the next few days.

This was odd to me since it closed ok on a 6 arc go gauge so I know the chamber plus headspaced rubber city bolt closes in min sammi spec. Must be the brass… this was super frustrating but I’m just glad I discovered this while I was still at the house and not at the range.

 

[black5.3]

Ugh. Had the ammo all loaded up and ready to go on Friday night. Since I’m using new Alpha brass I incorrectly assumed I wouldn’t need to do any kind of shoulder bump and only have to chamfer/deburr and put some dry lube on the neck for bullet seating. Luckily before heading to the range this weekend I decided to test a piece of unloaded new brass to see how easily it chambered And I couldn’t really get it to chamber at all. It was way too tight (had to mortar to get it out). I had to end up bumping the shoulder back about 4 thou in order to get it to chamber and unlock easily. I hope to finish the ammo tonight and get to the range within the next few days.

This was odd to me since it closed ok on a 6 arc go gauge so I know the chamber plus headspaced rubber city bolt closes in min sammi spec. Must be the brass… this was super frustrating but I’m just glad I discovered this while I was still at the house and not at the range.

Interesting, I didn’t have to do anything with my virgin Alpha except lube the necks and run a mandrel through it.

 

[WeR0206]

Interesting, I didn’t have to do anything with my virgin Alpha except lube the necks and run a mandrel through it.

Hmm. Did you get a headspaced bolt and How tight was your barrel/bolt on a 6 arc go gauge? Mine closed but was super tight and I had to remove the extractor to close it. The chamber is probably something like .001” bigger than sammi min or right at it.

 

[DeathBeforeDismount]

@Veracity

Hey Scott,

Have you done any testing on the broadsword uppers for shift? Now that seekins is unobtainable for builders it looks like it may one of the better options for a precision upper?

 

[WeR0206]

@Veracity

Hey Scott,

Have you done any testing on the broadsword uppers for shift? Now that seekins is unobtainable for builders it looks like it may one of the better options for a precision upper?

Good luck finding a broadsword upper. They seem sold out everywhere.

 

[black5.3]

Hmm. Did you get a headspaced bolt and How tight was your barrel/bolt on a 6 arc go gauge? Mine closed but was super tight and I had to remove the extractor to close it. The chamber is probably something like .001” bigger than sammi min or right at it.

I sourced my own bolt(toolcraft dlc). I had a local gunsmith check headspace for me because he did it for free and thats a lot cheaper than buying a set of go-no go gauges. He didn’t give me measurements just said I was good to send it.

 

[Macht]

@Veracity

Hey Scott,

Have you done any testing on the broadsword uppers for shift? Now that seekins is unobtainable for builders it looks like it may one of the better options for a precision upper?

Post #203 is his reply to a similar question I asked. It's also in the original post.

 

[WeR0206]

I sourced my own bolt(toolcraft dlc). I had a local gunsmith check headspace for me because he did it for free and thats a lot cheaper than buying a set of go-no go gauges. He didn’t give me measurements just said I was good to send it.

Results from range trip/first 50 shots

Post in thread 'PVA now offering AR15 barrels!'
https://www.snipershide.com/shooting/threads/pva-now-offering-ar15-barrels.7230495/post-12202696

 

[BurtG]

Has anyone tested the G stuff like the Stratomatch or MRGG stuff?

 

[tyrider427]

Good luck finding a broadsword upper. They seem sold out everywhere.

I found mine on Brownells. I'll post some pics when I get a chance to get out.

 

[WeR0206]

I found mine on Brownells. I'll post some pics when I get a chance to get out.

Nice, how long ago did you buy it? I’ve pretty much abandoned trying to get one and instead pivoted to san tan tactical billet uppers (they are thermofit, have an anti rotation pin hole etc.).

 

[Bigjake83]

Good luck finding a broadsword upper. They seem sold out everywhere.

https://www.simplemanarmory.com/product/sons-of-liberty-broadsword-billet-upper-receiver-stripped/

I've also got a few Broadsword uppers with various barrel options.

 

[AXMC]

https://www.simplemanarmory.com/product/sons-of-liberty-broadsword-billet-upper-receiver-stripped/

I've also got a few Broadsword uppers with various barrel options.

Isn't that the M76 version? In order to make it work, wouldn't you have to cut off the anti rotation tabs from the handguard or mill in slots for them like on the M89 version? I believe it's also just slightly smaller at the flare in the receiver, so the M89/L89 handguard would sit a little proud since it's slightly larger in diameter than the M76/wedgelock.

 

[Bigjake83]

Isn't that the M76 version? In order to make it work, wouldn't you have to cut off the anti rotation tabs from the handguard or mill in slots for them like on the M89 version? I believe it's also just slightly smaller at the flare in the receiver, so the M89/L89 handguard would sit a little proud since it's slightly larger in diameter than the M76/wedgelock.

Oh hell I don't know, I just saw somebody couldn't find a broadsword upper so I posted a link.

 

[AXMC]

Oh hell I don't know, I just saw somebody couldn't find a broadsword upper so I posted a link.

Ok. Thought maybe you had made one work.
Thanks

 

[AXMC]

Anybody test a L89 mated not to a broadsword, but instead a regular milspec style upper to see how much extra rigidity is gained ( if any) with a broadsword upper?

 

[33jeep]

Has anyone tested the G stuff like the Stratomatch or MRGG stuff?

My 18" 6ARC Stratomatch is .5 mil. Don't know about MRGG.

 

[BurtG]

My 18" 6ARC Stratomatch is .5 mil. Don't know about MRGG.

That’s disappointing. Will have to build out my proof 6arc barrel when the mlok Vltors get dropped

 

[AXMC]

My 18" 6ARC Stratomatch is .5 mil. Don't know about MRGG.

Only .5 mil shift?

 

[33jeep]

Yes, .5 mil low off bag and barricade or clipped into tripod close to receiver.

 

[BurtG]

How’s the accuracy ?

 

[AXMC]

Yes, .5 mil low off bag and barricade or clipped into tripod close to receiver.

Bendy Bill at work again

 

[33jeep]

How’s the accuracy ?

It shoots pretty consistent .6-.7" 10 round groups. They are just in different places.

 

[brutus1776]

I’ve been following this test since I first saw it posted on IG a while back.

I’ve ran these tests and through a bunch of positions, not just bipod far/near in modified prone etc.

My question is:
How does one accurately diagnose if the shifts are 100% mechanical shift in the rifle vs. a parallax/npa issue in different positions?

 

[putput30]

Has anyone tested the G stuff like the Stratomatch or MRGG stuff?

I'll test out my mrgg once I figure what scope I want to throw on it. Hopefully it's not much lol. I do have one question, do small frames or large frames show more poi shift, or are they pretty equal?

 

[JR1200W3]

My question is:
How does one accurately diagnose if the shifts are 100% mechanical shift in the rifle vs. a parallax/npa issue in different positions?

That's the $64,000 question.

My best answer is this:

1. Here's a 5x5 of a positional test I did with a Seekins SP10 builders kit that I built out.

Here's just a prone load development target for the same gun.

So when you look at the second photo you get a pretty good idea of the gun's accuracy. When you look at the first photo you see some of that accuracy but you also see some deviation. The first Prone -Far Bipod has a mean POI just under the center black line that is lined up with the .3-.4" white squares. The following two groups show a MPOI pretty much at the second line, just under the centerline. So about half a tenth a mil. The Tripod group is a complete outlier. The last group (left to right) is a repeat of the first group, Prone-far bipod. It is a zero shift commensurate with Group #2 and Group # 3(L->R). So I would grade the Seekins SP-10 as 0 mils zero shift. I attribute the tripod group as a NPOA/ positional shift as I was trying to manage wobble zone and driving the gun completely different than I do in the prone or off a bag due to the increased wobble zone of "free-gunning" a clipped in tripod. The first group and last group needs an aggregate zero. Pretty close to groups 2&3.

2. Here's the contextual stuff that helps me calibrate my shit group analysis. I have dug into positional shooting quite a bit lately. I shoot a fair amount of PRS and started some isolation drills for positional shooting with my bolt guns. I started with a 5rd group at 100yds in the prone with no time pressure. Then I shot a 5rd group with no time pressure off a barricade and bag on a second dot right next to the prone zero group. Then I shot 5 individual rounds in a dot on a ProTimer. Starting at the ready, all gear in hand, on the beep drop into a barricade position and fire one shot in the 100yd dot. I did this for 5rds and compared the three 5rd groups. No zero shift. Then I used a tank trap and three 1" dots at 100yds on paper. I shot one round from the center crotch of the tank trap in the first dot, one round from the tip of one of the legs on the second dot, and then returned to the center crotch of the tank trap and fired a third round on the third dot, all in a ProTimer. So three rounds, three shots, three positions, three dots. I did this three times as three individual strings. So each dot would end up with an aggregate of three rounds from the same position, albeit from three different strings of fire. Using 9 rounds, 9 position changes, 3 dots and 2 positions over the course of three times strings, I built an aggregate. No POI shift.

This exercise helps calibrate your fundamentals and NPOA. I did this with two other guys. One guy did have a repeatable trend to throw rounds right on position changes. This is how you suss out NPOa influences after you shoot a diagnostic positional test. It is a series of escalating dot drills that can illuminate positional influences

That's my best answer.

 

[WeR0206]

https://www.simplemanarmory.com/product/sons-of-liberty-broadsword-billet-upper-receiver-stripped/

I've also got a few Broadsword uppers with various barrel options.

Isn't that the M76 version? In order to make it work, wouldn't you have to cut off the anti rotation tabs from the handguard or mill in slots for them like on the M89 version? I believe it's also just slightly smaller at the flare in the receiver, so the M89/L89 handguard would sit a little proud since it's slightly larger in diameter than the M76/wedgelock.

M89 Broadsword uppers are now in stock at Rooftop Defense...if I didn't just buy a San Tan Billet Upper I'd get grab one

Sons of Liberty Gun Works AR/M4 Stripped Broadsword Upper Receiver | Rooftop Defense

Buy Sons of Liberty Gun Works AR/M4 Stripped Broadsword Upper Receiver | Sons of Liberty's flagship stripped upper made for use with their Drivelock rails.

www.rooftopdefense.com