ARX100 quick-detach barrel accuracy test

[Aries144]

I don't think sub MOA. I think there is some lateral movement, I just can't measure it. I believe it is adding less than .5 MOA to overall group size. To test that kind of thing said match barrel and a machine rest would really be needed. When it comes to sub MOA accuracy, that's when all the little things like rigidity and bolt lockup reportedly start to matter- I'm not a benchrest shooter though.

We did some math and determined that .001" of barrel wobble, measured at the gas block/heatshield interface, would add .9(something) inches to group size at 100 yards. My example can not be deviating more than .0005" at that location. It could be less, I just can't measure it because my current setup isn't precise enough.

[Kain]

I never bashed the rifle as a system. I have no idea how you came to that conclusion as I never stated anything to that effect.

75gr PPU is match ammo. Molon has reviewed it in detail. It is a known quantity.

Beretta's spec is 4 MOA from a machine rest with Fiochi ball. Beretta has stated in writing: "you should expect to attain at least a 4" shot group at 100 yards using 64 grain Speer Gold Dot GDSP or comparable ammunition."

I believe my ARX100 is at the low end of the accuracy spec, not out of spec.

You have fixated on the accuracy report. The main thing I have attempted to contribute is that the quick detach barrel system has little negative effect on accuracy. Each ammo type showed very nearly the same group sizes with an optic mounted to the receiver rail as they did with an optic mounted directly to the barrel using an Ultimak mount. If something were wrong with my barrel mounting setup, group sizes with the mount in each position would not have been nearly identical.

If I were a terrible shot or poorly acclimated to the rifle, consistent group sizes for each ammo type would not happen, instead group Extreme Spread would be erratic across multiple groups using the same ammunition. The ES of groups sizes, shooting 10 shot groups, has been consistent within .5 MOA for each group. I therefore estimate my margin of error must be less than .5 MOA. This means that any negative affect on accuracy that the detachable barrel system has must be equal to or less than that, since it is not detectable. Obtaining the exact difference via testing would require running the same test again, but with a machine rest to remove human error from the equation. Can you explain to me why this logic is flawed?

A higher magnification is not needed just because my abilities and truthfulness are doubted, nor because that's the way others have done it. Consistency is such that there is no cause for me to believe that human error is a significant factor in the test, which is all the addition of a magnified optic could possibly address. In addition, why on earth would claiming to have used a 10x optic make any difference? There is absolutely no way I could prove I had done so, since I lack a video camera and the apparent level of distrust I've been shown here is beyond the use of photographic evidence- 'I might have faked it!' With the level of distrust I've been shown here, there is nothing short of an invitation to witness a test, using a machine rest, in person, that could possibly satisfy the collective skepticism here- all because I rendered my results in text format instead of including pictures and video.

Thus the comment about, and accusation of, cynicism. I don't like those kinds of people. I'm glad they'll get nothing from this. Move on and let others more experienced and less skeptical decide for themselves if what I've provided feels accurate and truthful. Skepticism is no virtue.

Your original post stated you had "proved" X(Post is now down and I can't quote it from memory) about the Beretta ARX. Then when your testing methods and set up(Optic choice, ammo, Barrel mounted rail for example, The rail on the barrel still puzzles me since if it is clamped to the barrel for the entire test I would be expecting it to affect the barrel harmonics some how) are questioned your reaction is not to take the criticism and remove possible variables that would allow clearer data on whether your issues here in lie with the barrel, or the lock up, or perhaps the trigger which has been reported to be in the 10 pound range, or something else entirely but instead you state that you will do no further testing and refuse the even possibility of using a scope. If you believe that the barrel is the limiting factor here there is no reason not to attempt to confirm this with a high magnification optic and match ammo. With your response it comes across as if you intention is to bash the rifle and not offer or collect useable data, hence my response.

With that said, if you feel that the QD lock up on the barrel is fine, and not causing significant accuracy inconsistencies and that the barrel is the cause of the group dispersion then why not use a scope and remove a variable? Answer me that from a logical standpoint. If the issue is that the barrel is truly incapable of sub 4MOA groups then this would provide data that would be useful as well as removing variables. Use of a red dot with a 4MOA dot is only going to be seen as a limiting factor here since we are now testing the precision of a rifle barrel.

In regards to ammo. Yes, I am aware of Molon's testing of it. That said, he did test the capabilities of that ammo using a rifle with a high magnification optic, and not a red dot, so I still don't see how, if we are looking at the accuracy of the barrel since your current claim is that the movement of the barrel is not adversely affecting accuracy enough to matter, why you wouldn't attempt the same. Again we are attempting to remove as many variables here as possible to get raw data.

Also, to quote him, among many others, every barrel is a law unto itself. I have seen rifles shoot very nice groups with 75gr ammo, as well as others who would group very well with other ammo not shoot match 75gr worth a good goddamn so there is the possibility that the barrel simple does not like the 75gr Prvi. Using other ammo of "known quantity" would remove this variable.

My ending points are that there are still too many variables here for any manner of conclusion to be drawn, let alone anything to be proven. From optic selection, to mounting optics to the barrel, which again I am unsure of what you are attempting to prove here with that particular test, and for that matter I still want to see that particular mount because from how I am envisioning the thing, it much have a truly prodigious sparer to be usable. Were all groups shot with that rail mounted there, or were only one part of the test conducted with that rail there? I cannot see how a rail mounted directly to the barrel is not going to cause some issues. As well as ammo selection.

[Aries144]

Your original post stated you had "proved" X(Post is now down and I can't quote it from memory) about the Beretta ARX. Then when your testing methods and set up(Optic choice, ammo, Barrel mounted rail for example, The rail on the barrel still puzzles me since if it is clamped to the barrel for the entire test I would be expecting it to affect the barrel harmonics some how) are questioned your reaction is not to take the criticism and remove possible variables that would allow clearer data on whether your issues here in lie with the barrel, or the lock up, or perhaps the trigger which has been reported to be in the 10 pound range, or something else entirely but instead you state that you will do no further testing and refuse the even possibility of using a scope. If you believe that the barrel is the limiting factor here there is no reason not to attempt to confirm this with a high magnification optic and match ammo. With your response it comes across as if you intention is to bash the rifle and not offer or collect useable data, hence my response.

First, testing with a 10x optic does not remove any variables. It is certainly more optimal than a red dot when using targets which rely on a centered point for alignment, but a target specifically implemented to frame a 4 MOA dot at the intended distance makes even slight misalignment very obvious. The edges of the dot are centered inside a white diamond which is surrounded by a black diamond on a white background. The white center diamond displays symmetrical corners when the dot is aligned and the black provides clear contrast. When used from a bench or prone with the rifle bagged at the front and back, the shooter can adjust natural point of aim to align, breath, hold at precise alignment, and fire the shot.

Second, even if a 10x optic were used, you'd have to trust that I had actually used it and that I used it to the best of human ability. Up to this point you and others have displayed a striking level of distrust and disrespect. You want a 10x optic because you have enshrined it in your mind as a peerless standard, baselessly disbelieve it's possible for a 1x optic with a 4 MOA reticle to offer acceptable precision, and doubt my ability to operate the ARX100 to the same degree as the AR15 besides!

I provided information which should tell you that my shooting precision is sufficient: repeatable 2 MOA performance with a lightweight barrel AR15 with 4 MOA Comp M2 aimpoint using 55gr FMJ Hornady hand loads and dry firing the ARX100 without reticle movement. You should be able to extrapolate that the AR15 rifle/ammo configuration is likely incapable of mechanical 1 MOA performance and that repeatable performance of 2 MOA with a 4 MOA reticle indicates acceptable precision from that user/equipment/target combination.

Third, I do not own a 10x scope.

With that said, if you feel that the QD lock up on the barrel is fine, and not causing significant accuracy inconsistencies and that the barrel is the cause of the group dispersion then why not use a scope and remove a variable? Answer me that from a logical standpoint. If the issue is that the barrel is truly incapable of sub 4MOA groups then this would provide data that would be useful as well as removing variables. Use of a red dot with a 4MOA dot is only going to be seen as a limiting factor here since we are now testing the precision of a rifle barrel.

Use of a 10x scope does not remove any variables. It would only serve to placate fixation. Furthermore, I have already been censured and dismissed by our apparent resident Druid of The Dogma of Science for Dogma-inappropriate Use of the English Language in a Science Related Conversation. There is nothing for me to gain by such a course of action and nothing to be gained by yourself since my integrity and competence have already been called into question.

Also, to quote him, among many others, every barrel is a law unto itself. I have seen rifles shoot very nice groups with 75gr ammo, as well as others who would group very well with other ammo not shoot match 75gr worth a good goddamn so there is the possibility that the barrel simple does not like the 75gr Prvi. Using other ammo of "known quantity" would remove this variable.

Certainly, however this test was performed to for my personal benefit with the ammunition I have on hand, primarily to determine if some flaw in the quick attach barrel system of my example was a significant factor in the group sizes I'd witnessed. The tested factory ammunition types did not produce the accuracy I would have liked, but were still consistent and useful to see if there was a massive change in dispersion after mounting the optic to the barrel. There wasn't.

My ending points are that there are still too many variables here for any manner of conclusion to be drawn, let alone anything to be proven.

Again, I claim that my target type allows acceptable precision with a 4 MOA aiming point. I provided a written report that should be sufficient for the experienced shooter reading it to determine that consistency and precision of the user and equipment is acceptable for the purpose of establishing whether or not the barrel was shifting in alignment with the receiver-mounted optic, causing enlarged dispersion.

From optic selection, to mounting optics to the barrel, which again I am unsure of what you are attempting to prove here with that particular test, and for that matter I still want to see that particular mount because from how I am envisioning the thing, it much have a truly prodigious sparer to be usable. Were all groups shot with that rail mounted there, or were only one part of the test conducted with that rail there? I cannot see how a rail mounted directly to the barrel is not going to cause some issues. As well as ammo selection.

Optic selection was because unlimited eye relief was necessary, as the optic would have to be mounted to the exposed barrel for part of the test. The optic also allowed consistency with the AR15 comparison rifle, as a 4 MOA red dot has been used with it to establish its consistent recorded accuracy potential (2 MOA).

The mount is an Ultimak Model# M1-B AK mount. It is a commonly used item and is easy to look up. It is designed to clamp directly to the barrel of a rifle to serve as an optic mount. The mount had to be shimmed, as the exposed barrel of the ARX100 was almost exactly .1" too thin. The mount was absolutely rigid as installed and I was unable to noticeably shift it by torquing the barrel and mount against one another strongly by hand and comparing witness marks on the barrel and mount.

The first groups were shot with each ammo type with the optic mounted to the receiver rail, without the ultimak in place. The next groups were shot with the ultimak mounted to the barrel, with the optic still attached to the receiver rail. The final groups were shot with the optic mounted to the ultimak, mounted to the barrel.

Had the respectively witnessed 4.25", 4.75", and 6" largest extreme spreads of factory ammunition types been primarily due to the barrel shifting in the receiver shot-to-shot, mounting an optic directly to the barrel, to ensure alignment of the optic and barrel by directly mating them, would have eliminating barrel movement as a factor and displayed measurably decreased group extreme spreads. There was no measurable difference, therefore any movement of the barrel cannot be the primary reason I'm seeing 4 MOA minimum ES with the ammunition types tested.