AR Positional POI Shift Test

[Bigjake83]

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.

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Now I see what y'all are talking about I didn't know they had a earlier model without the anti-rotation tabs machined in the upper for the handguard.

All of mine are the M89, as shown in this build review. I've got 4 or 5 now and I'm extremely impressed with the quality and rigidity.

Geissele Cut Rifled SPR Build and Barrel Evaluation. (Part 4 (Load Development 28MAY25) Update!!!

Hello Snipershide! Geissele Automatics has been offering Single Point Cut Rifled Barrels for close to two years now but they've been restricted to the 6 ARC Stratomatch or blanks that the end customer could have custom turned from barrel manufacturers like White Oak Armory. Two weeks ago...

www.snipershide.com

 

[WeR0206]

Now I see what y'all are talking about I didn't know they had a earlier model without the anti-rotation tabs machined in the upper for the handguard.

All of mine are the M89, as shown in this build review. I've got 4 or 5 now and I'm extremely impressed with the quality and rigidity.

Geissele Cut Rifled SPR Build and Barrel Evaluation. (Part 4 (Load Development 28MAY25) Update!!!

Hello Snipershide! Geissele Automatics has been offering Single Point Cut Rifled Barrels for close to two years now but they've been restricted to the 6 ARC Stratomatch or blanks that the end customer could have custom turned from barrel manufacturers like White Oak Armory. Two weeks ago...

www.snipershide.com

I have 3 of the M89 rails and I like them a lot as well. FWIW I think the OEM for the rails is Hodge Defense.

 

[AXMC]

I have 3 of the M89 rails and I like them a lot as well. FWIW I think the OEM for the rails is Hodge Defense.

Hodge may have designed the lockup, but doesn't manufacture anything.
.Pretty sure they're Mega/Zev

 

[WeR0206]

Hodge may have designed the lockup, but doesn't manufacture anything.
.Pretty sure they're Mega/Zev

Yeah they seem to have the exact same finish as Zev parts.

 

[Wormydog1724]

I thought ICON was OEM for SOLGW, could be wrong but they have the same drivelock handguard and the upper is similar, not as thiccc right behind the threads tho.

 

[AXMC]

Personally I think Zev does them for both (plus Expo and anybody else with that particular NiAc sealed anodize)

 

[WeR0206]

Broadsword-89 also in stock now at brownell's

SONS OF LIBERTY GUN WORKS BROADSWORD-89 BILLET UPPER RECEIVER

Check out SONS OF LIBERTY GUN WORKS BROADSWORD-89 BILLET UPPER RECEIVER available Online at Brownells Today and many more Rifle Receivers & Parts products are available in our Gun Parts Department.

www.brownells.com

 

[Black max]

Great uppers when used with the M89 handguards!

 

[AXMC]

If anyone can't find a broadsword upper but wants to mount a SOLGW L89/M89, another option is the billet flared upper from Icon defense. The finish/lines precisely match the l89 handguard (another reason I think they're both produced by mega/Zev), plus it has the advantage of matching the lines of a mil-spec lower better than the broadsword does.
And to top it off, it's cheaper.

 

[Mike_in_FL]

If anyone can't find a broadsword upper but wants to mount a SOLGW L89/M89, another option is the billet flared upper from Icon defense. The finish/lines precisely match the l89 handguard (another reason I think they're both produced by mega/Zev), plus it has the advantage of matching the lines of a mil-spec lower better than the broadsword does.
And to top it off, it's cheaper.

What grip is on the lower? I like how vertical it is.

 

[AXMC]

What grip is on the lower? I like how vertical it is.

It's the TDX-0 with beavertail by Ergo

 

[Thebiglebowski]

If anyone can't find a broadsword upper but wants to mount a SOLGW L89/M89, another option is the billet flared upper from Icon defense. The finish/lines precisely match the l89 handguard (another reason I think they're both produced by mega/Zev), plus it has the advantage of matching the lines of a mil-spec lower better than the broadsword does.
And to top it off, it's cheaper.

Icon is making all of SOLGW uppers/lowers. Mike mentioned that it was different machines than Mega.

What lower is that your using?

 

[AXMC]

It's just an Anderson

 

[AXMC]

Icon is making all of SOLGW uppers/lowers. Mike mentioned that it was different machines than Mega

It's certainly possible. However if they are, they're using the same anodizer and/or recipe as they also exactly match the stuff Mega/Zev is OEMing for Expo/Primary Arms. I guess if Icon was founded by the guy who originally founded Mega before the sale, that would make sense.

 

[JR1200W3]

Here's my contribution to this discussion, for whatever it's worth. Using my friend's 14.5" 6.5 Creedmoor AR10 with a Craddock Precision Bartlein barrel using an SLR handguard with aluminum barrel nut and regular Aero M5 upper, I shot 2 sets of groups. 1 from prone with bipod and rear bag and 1 clipped in to my Fatboy tripod via ARCA and the RRS Anvil head attached just forward of the magwell.

The group did seem to shift from being left of center and slightly high (.52" left and .12" high) to being even more high but less left (.40" high and .18" left). My group was notably larger though from standing tripod, so statistically it's hard to say how much of a real shift is there. Based on talking to Paul Craddock, this minor shift would basically go away if the rifle had a handguard with a steel barrel nut, at least according to him. Personally, if I'm building a precision gas gun I don't think I'd worry about a semi-mono upper at all and just get a solid handguard with a steel barrel nut, at least when speaking AR10s.

View attachment 8792410
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Your results might be different if your groups had better precision

ETA: not trying to be a dick. Just saying that the consequences of a floating zero is more relevant to precision rifles meant for shooting targets at distance. If you're shooting 2.5" groups then it's not really a precision rifle capable of effective use on small targets at distance. I think the priorities are getting your rifle to be precise enough to hit 2 moa targets(at distance). Usually meaning a sub-moa rifle at 100. Then moa capable as a shooter. Then diagnose shifting zeros to isolate shooters input versus mechanical shortfalls in the rifles design. If all of that falls inside the noise of the precision capability of the ammo or barrel, then it's impossible to isolate.

 

[JR1200W3]

I understand what you're saying, but I'll also say that most people don't shoot large enough group sizes to see what their rifle system is actually capable of in the real world, statistically speaking. And part of the reason my group sizes were larger is because they were 17 and 19 shot groups, that's just the nature of dispersion. I think that over large sample sizes, a 1.6 moa group from a prone / bench position is fairly common of most precision / DMR oriented ARs. My tripod shooting could definitely use some work, though I think most people's group sizes would increase that same amount going from prone to standing tripod.

To clarify, I don't think my test was the end-all be-all and yes could probably be done better. I was more trying to show the worst case scenario of a very lightweight handguard (SLR) with an aluminum barrel nut in a lightweight AR10 platform and personally, I thought the shift in that system would have been plainly obvious, but at least from my testing it seemed pretty miniscule. Take it for what it's worth I guess.

Prone

Prone and Kneeling barricade/ bag

POI test

I would trade a little confidence interval for less white noise. We can debate sample size but when your distribution is 2.5moa, the massive width of your distribution kinda reduces the accuracy of your confidence interval

 

[AXMC]

That Seekins...uses an enhanced style upper not a BAR barrel nut attachment method, right?

 

[JR1200W3]

Correct. Semi monolithic. Just like the Aero Enhanced

 

[AXMC]

So you're seeing a .2 to .25 mil shift from far bipod to tripod?

 

[JR1200W3]

So you're seeing a .2 to .25 mil shift from far bipod to tripod?

I only tested it once and you see what it looks like. But I don't think that's from rail flex. I'm 95% sure it's just driving the gun differently. The flaw in this testing is that it's not definitive in separating mechanical design from shooter influence.

It's not possible to drive the gun the same way from the prone, far bipod, rear bag versus locked into a tripod head. So far, to achieve the most precision in group size, I think those two positions require different shooter input. I think you could try to drive the gun, in a tripod, the same way you do prone but it would become null because you'd give up so much precision. So to extract as much "accuracy" as possible you end up using different technique which creates the zero shift. That's my current philosophy on it. It's also why I shoot off a bag and TAC table when shooting off a tripod whenever able. Because it's the most synonymous with shooting off a barricade and bag. But for this test it would make the tripod position just a replicate of the barricade/ bag. I think the difference in prone far bipod vs rear bipod does the best in isolating rail flex from shooter input.

What's more significant to me about that POI test I posted is the .1 mil zero shift from the first prone, far bipod, rear bag on the left to the last version of the same in the right. That tells me there's at least a .1 of shooter inconsistency in input going on.

 

[JR1200W3]

And that's my point when I mention larger sample sizes. It's my bet that the .1 mil "shift" you are noticing here would disappear into the natural cone of fire of the system if you fired a 20 or 30 shot group. And moreover, the "shifts" we see in other positions might also disappear entirely.

So.... you wouldn't be able to see, or you would have a much, much harder time seeing the shift? That seems counter-productive and is the point I made that increasing sample size in a big ass group only increases white noise. The gun you were shooting almost certainly has rail flex and should show it. The fact that your 2.5moa groups mask it, proves my point.

 

[JR1200W3]

No, I'm saying in the specific case of your zero "shifting" from prone and then back to prone again, there is no real zero shift. It's simply the natural dispersion of the system and you think it's you as the shooter not "driving the rifle" the same when you went back into prone. And my theory is that it's the same for the positional shooting as well. That there is no real zero shift, it just looks like there is because you're only shooting 5 shot groups.

For example, I ran into this issue when zeroing my hunting rifle this year. I would lay down and shoot a 5 shot .3" group, then let the gun cool and repeat. And then the group looked like it shifted .05 or .1 mil in some direction. But in reality, when I fired 5x 5 shot groups, and then took the exact center of each group and overlayed them, it gave me a much more repeatable zero because I was factoring in the inherent "randomness" of the system.

The argument that there is never a zero shift induced by a shooter or a gun because if you shoot enough rounds they will all just look like one big ass mess, doesn't resonate with me.

But if you want to make that argument with some credibility I think you need demonstrate that you can put together a gun and shoot it well enough to produce smaller groups than 2.5moa. Because so far it just looks like neither you or the gun isn't precise enough to prove or disprove your theory. It just looks like you got this "big ass group feedback loop " going on.

 

[BurtG]

No, I'm saying in the specific case of your zero "shifting" from prone and then back to prone again, there is no real zero shift. It's simply the natural dispersion of the system and you think it's you as the shooter not "driving the rifle" the same when you went back into prone. And my theory is that it's the same for the positional shooting as well. That there is no real zero shift, it just looks like there is because you're only shooting 5 shot groups.

For example, I ran into this issue when zeroing my hunting rifle this year. I would lay down and shoot a 5 shot .3" group, then let the gun cool and repeat. And then the group looked like it shifted .05 or .1 mil in some direction. But in reality, when I fired 5x 5 shot groups, and then took the exact center of each group and overlayed them, it gave me a much more repeatable zero because I was factoring in the inherent "randomness" of the system.

No.


And you don’t need to shoot 3. Boxes of a
No to tell if a gun is going gm be interesting or not.

 

[JR1200W3]

@shootingnut here's some additional thoughts for you. By using your hunting rifle as an example, you've just introduced a whole another slew of variables. Number one. I don't know what you're calling a hunting rifle, but it is absolutely more difficult to shoot an 8 lb magnum size case head cartridge as consistently as a 22 lb 6.5 Creedmoor. So I would absolutely expect to see point of impact shifts from one group to the next as a simple shooter-induced event. I'm also guessing that you're hunting rifle doesn't have a 30 round magazine, so when you shoot your larger sample size you are very likely breaking position to reload and so your shooter induced point of impact changes are likely baked in to your group size. You're interpreting it as "natural randomness" When there is a real and controllable factor that's creating the aggregate group size. And then on top of that hunting rifles typically aren't going to shoot large sample sizes well, simply because their barrels are too thin to withstand the heat. So some of that "natural randomness" could be a hot barrel starting to walk. So I question the practice of just chalking everything up to natural variation or randomness. Because I think by studying this whole discipline and art, you can start to separate and isolate the factors that cause POI shifts and we might find out that it is not simply natural and inevitable variation or randomness. It might be controllable factors that you can isolate. And then your natural and inevitable. variation is much smaller than you think. Especially from one platform to the next. Perhaps you cannot paint wildly different rifles with the same broad brush.

 

[JR1200W3]

I never said "never a zero shift induced by a shooter". You're putting words in my mouth now. And I don't care what "resonates" with you. Only what is true in reality. If you want to prove my theory wrong (and I would be happy if you did, since you clearly have a more precise gas gun than I do), then please shoot a 20 shot group from prone without breaking position at all and then see if the resulting group would engulf / encompass the "zero shift" you think you're seeing. Should be a pretty easy test for a shooter of your caliber.

I've done that once with my 25 GT for one of these internet arguments. 30rd group. I'm taking this gun to a match on Saturday and it is cleaned, seasoned and zeroed and my ammo is loaded. I'm not going to shoot a 30 round group every time some dickweed on the internet wants to argue about sample size. The photos I posted(minus the positional test target) represent 35 rounds, shot in sequence over individual shot groups and over three visits to the range. I am pretty happy with my zero and the consistency of the guns accuracy. That's the point of all this. It's not just hypothesizing on the internet. It's about getting your gun and yourself ready to go do something with it. Now compare your work to mine. Who is more ready to do something meaningful?

 

[WeR0206]

Dickweed? Alright lol. I did go out and do real world testing and posted my results, but guess I should've just kept it to myself. Good luck at your match this weekend.

 

[JR1200W3]

Dickweed? Alright lol. I did go out and do real world testing and posted my results, but guess I should've just kept it to myself. Good luck at your match this weekend.

Luck isn't a strategy friend

 

[spife7980]

I did go out and do real world testing and posted my results, but guess I should've just kept it to myself.

Agreed, using those group pics as evidence of anything is sort of embarrassing.