M16A5 Stock by VLTOR

[BufordTJustice]

For what it's worth....

This weekend I tested under extremely highspeed camera (see new avatar) the A5 system vs std and H1 buffers.

The plan was to test it under full auto and get cyclic rate along with bolt bounce and etc. Ran out of time for these tests, and cyclic rate wasn't reliable for number under semi-auto. So all I ended up getting was bolt bounce and carrier movement between the three systems.

Short and sweet, I can easily confirm under every upper I tried, 12.5" DD, 16" with swithblock, etc etc, there was less than zero bounce on the A5 lower. Noticeable bounce on the standard carbine, less on the H1 with the switchblock. This shouldn't be of much suprise to anyone really.

What did surprise me was the amount of movement the carrier had above and below the bore. When the carrier is slighting forward, the is an obvious drop in it's ride height as it passes over the hammer. On the Non-A5 guns, there was noticeably more wiggle in the carrier before resting, the A5 still had a little play just because the carrier is of course under-sized for the upper. I have video, but it's very large and pretty uninteresting so I'm unlikely to post it.

No real amazing conclusions or cyclic numbers (that'll have to wait until next time and). I'm going to try and get that kit installed on a full auto lower, and even then I doubt I'll use highspeed, rather probably just measure the sound and get cyclic rate. Maybe a few weeks at the soonest.

Now, all that said, I don't care about much at all as long as it's not a large amount, I shoot semi only but I do get that the bounce is more indicative of other potential issues (weak action force, FTF?). What I find to be interesting the the extra weight forcing that next round into the chamber, still have testing to do, but as of right now, I really can't see not spending the extra couple of dollars to make a new build an A5. The company I was consulting for pretty much saw the same thing, I suspect all their new guns run A5 from now on, we'll see. Left a kit with them to play with.... So now they owe me a kit :\

As far the seat of the pants testing between a few users... It's close. No one said OMFG the A5 is sooo much smoother. There was a nod to the A5, but with any more than a few seconds between the two guns it was almost too close to tell - as the shooter. One of the guys watching was talking about how the shooter appeared to be under less recoil with the A5, but nothing concrete. I suppose it would be cool to test actual recoil between the two with a better tool than pants.

EDIT: I suppose rather than cylic rate, when I get to re-test this, it will be with carrier/bolt velocity and not RoF. I can't compare the two directly, but velocity between suppressed, not, h3 h4 h5 weights, barrel lengths, etc will be easier.

Thanks for posting this. I would love to see the video. Youtube has no upload filesize limit right now. I uploaded a 2GB 720p video a while back on another forum and it was my first upload. I realize you would have to edit it first.

My first thought about extraneous carrier movement inside the upper is an out-of-spec upper or carrier (or both). Using my finger, I cannot force any wiggle between the carrier and upper in any direction on my BCM 14.5" middy or my wife's PSA 14.7" middy.

Also, to clarify, did you see the carrier being pushed up as the front portion depressed the hammer, or did you see the carrier sink a bit as the front portion made it past the hammer?

[Noodles]

Thanks for posting this. I would love to see the video. Youtube has no upload filesize limit right now. I uploaded a 2GB 720p video a while back on another forum and it was my first upload. I realize you would have to edit it first.

My first thought about extraneous carrier movement inside the upper is an out-of-spec upper or carrier (or both). Using my finger, I cannot force any wiggle between the carrier and upper in any direction on my BCM 14.5" middy or my wife's PSA 14.7" middy.

Also, to clarify, did you see the carrier being pushed up as the front portion depressed the hammer, or did you see the carrier sink a bit as the front portion made it past the hammer?

2gb? Try 40-80gb. But I might get the A5 video can convert it small enough to upload.

I'm talking about a very slight amount of room here. The carrier fits in the upper, that means there is room to wiggle. And it does. Quite a bit. Less on the A5, my guess being there is more weight on the back of the carrier. For it to wiggle up and down a bit, it has to slide sheer off the back of the buffer weight or wiggle the weight along with it, no idea on which one.

It's not a problem or anything, it's just interesting to see. For reference, and exaggerated wiggle room on the way back would be carrier tilt.

From every angle I saw it on, it really looks to me like the carrier falls when it leaves the hammer going forward.

[sinlessorrow]

For what it's worth....

This weekend I tested under extremely highspeed camera (see new avatar) the A5 system vs std and H1 buffers.

The plan was to test it under full auto and get cyclic rate along with bolt bounce and etc. Ran out of time for these tests, and cyclic rate wasn't reliable for number under semi-auto. So all I ended up getting was bolt bounce and carrier movement between the three systems.

Short and sweet, I can easily confirm under every upper I tried, 12.5" DD, 16" with swithblock, etc etc, there was less than zero bounce on the A5 lower. Noticeable bounce on the standard carbine, less on the H1 with the switchblock. This shouldn't be of much suprise to anyone really.

What did surprise me was the amount of movement the carrier had above and below the bore. When the carrier is slighting forward, the is an obvious drop in it's ride height as it passes over the hammer. On the Non-A5 guns, there was noticeably more wiggle in the carrier before resting, the A5 still had a little play just because the carrier is of course under-sized for the upper. I have video, but it's very large and pretty uninteresting so I'm unlikely to post it.

No real amazing conclusions or cyclic numbers (that'll have to wait until next time and). I'm going to try and get that kit installed on a full auto lower, and even then I doubt I'll use highspeed, rather probably just measure the sound and get cyclic rate. Maybe a few weeks at the soonest.

Now, all that said, I don't care about much at all as long as it's not a large amount, I shoot semi only but I do get that the bounce is more indicative of other potential issues (weak action force, FTF?). What I find to be interesting the the extra weight forcing that next round into the chamber, still have testing to do, but as of right now, I really can't see not spending the extra couple of dollars to make a new build an A5. The company I was consulting for pretty much saw the same thing, I suspect all their new guns run A5 from now on, we'll see. Left a kit with them to play with.... So now they owe me a kit :\

As far the seat of the pants testing between a few users... It's close. No one said OMFG the A5 is sooo much smoother. There was a nod to the A5, but with any more than a few seconds between the two guns it was almost too close to tell - as the shooter. One of the guys watching was talking about how the shooter appeared to be under less recoil with the A5, but nothing concrete. I suppose it would be cool to test actual recoil between the two with a better tool than pants.

EDIT: I suppose rather than cylic rate, when I get to re-test this, it will be with carrier/bolt velocity and not RoF. I can't compare the two directly, but velocity between suppressed, not, h3 h4 h5 weights, barrel lengths, etc will be easier.

That movement of the carrier, is what led VLTOR to make the MUR. they did a lot, and I mean alot of stress testing on the bolt and determined that if they could eliminate the bolt from going into battery off center they could increase bolt life, so now they make the MUR.

[jbsmwd]

That movement of the carrier, is what led VLTOR to make the MUR. they did a lot, and I mean alot of stress testing on the bolt and determined that if they could eliminate the bolt from going into battery off center they could increase bolt life, so now they make the MUR.

Source please. I would really like to read that.

[Iraqgunz]

I can confirm this as I spoke to them about it when I did my write up. In addition you can look at the "sticky" area and read the Upper Receiver Flex Testing post from Kino Davis. The receiver was beefed up in areas that they determined would allow upper receiver flexing.

Source please. I would really like to read that.

[Noodles]

Fwiw, the type of wiggle I watched the carrier do was probably not due to upper receiver flexing, rather the small amount of tolerance in the upper that allows the carrier to slide freely.

I was cropped in pretty far so I didn't see much of the upper or lower, and I wasn't watching for it. Could be the case, but we were looking at a pretty strong billet upper as well as the forged on my gun, but either upper when used with the A5 lower had less wiggle than the billet lower+carbine RE. So this may be related but I think we're talking about a different issue.

That said, I saw somethings under highspeed that I never would have guess in a million years, so I could be dead wrong about cause and effect of the carrier wiggle. For instance, I watched a tactical 870 at 10000fps which is about less-to-mid range for this camera setup. When shot, I watched the magazine tube come whip about .100" from touching the barrel at the muzzle, due to whip of the tube and barrel. The thing is, there is only 4-5" of unsupported length there. And if you flex it by hand it pretty much doesn't move at all. But play the footage back and that 4-5" has a crazy amount of whip, makes no sense to me, but there it is.

My guess is that a lot of internet BS could be put to rest with a handful of highspeed cameras.

[markm]

So this may be related but I think we're talking about a different issue.

I think you're right. There's a lot of room for the carrier to rattle around in an upper.

[Iraqgunz]

Hopefully Kino will chime in. It is my understanding (markm was there as well) that they did in fact use high speed photography and they observed the flexing with the receiver.

What they stated made sense to me.

Fwiw, the type of wiggle I watched the carrier do was probably not due to upper receiver flexing, rather the small amount of tolerance in the upper that allows the carrier to slide freely.

I was cropped in pretty far so I didn't see much of the upper or lower, and I wasn't watching for it. Could be the case, but we were looking at a pretty strong billet upper as well as the forged on my gun, but either upper when used with the A5 lower had less wiggle than the billet lower+carbine RE. So this may be related but I think we're talking about a different issue.

That said, I saw somethings under highspeed that I never would have guess in a million years, so I could be dead wrong about cause and effect of the carrier wiggle. For instance, I watched a tactical 870 at 10000fps which is about less-to-mid range for this camera setup. When shot, I watched the magazine tube come whip about .100" from touching the barrel at the muzzle, due to whip of the tube and barrel. The thing is, there is only 4-5" of unsupported length there. And if you flex it by hand it pretty much doesn't move at all. But play the footage back and that 4-5" has a crazy amount of whip, makes no sense to me, but there it is.

My guess is that a lot of internet BS could be put to rest with a handful of highspeed cameras.

[SteveL]

That movement of the carrier, is what led VLTOR to make the MUR. they did a lot, and I mean alot of stress testing on the bolt and determined that if they could eliminate the bolt from going into battery off center they could increase bolt life, so now they make the MUR.

I can confirm this as I spoke to them about it when I did my write up. In addition you can look at the "sticky" area and read the Upper Receiver Flex Testing post from Kino Davis. The receiver was beefed up in areas that they determined would allow upper receiver flexing.

I had no idea this was the case. I never realized the MUR offered any real benefit over uppers from any other top quality manufacturer. Apparently I was wrong.

[markm]

Yep. They used a laser to measure the flex just by pushing down on the end of the barrel. A standard flat top is VERY thin under the rail. When you go from an A2 upper to a flat top, you lose a lot of strength.