I'm shooting Book load max charges ( Flattened primers) 75gr ELD in front of 25grs of Re#15.5 and I bolt locks open on very last shot When burning Alliant Power Pro 2000-MR (Again book max charges) 28.2 grs behind an 80.5 Berger full bore bullet the bolt doesn't lock open, Why? I'm pushing those bullets above 2900FPS and MOA accuracy. Again, why?
224 Valkyrie bolt doesn't lock open with Alliant Power pro 200-MR but does with Re#15.5
- Thread starter Ironworker
- Start date
BKA
Gold $$ Contributor
No knock against this site or the plethora of informative members here, but the semi-auto platform is not really in the wheelhouse. Searching websites dedicated to the semi-auto platforms may be most useful.
Depending on the firearm, there are lots of variables that can contribute to the issue you are describing. Gas guns like things to be clean and lubricated properly to function reliably. My second thought would be that the gun is under gassed for the Alliant Power Pro 2000-MR load. If an AR15 with an adjustable gas block, open it up a half turn and see if that helps.
Depending on the firearm, there are lots of variables that can contribute to the issue you are describing. Gas guns like things to be clean and lubricated properly to function reliably. My second thought would be that the gun is under gassed for the Alliant Power Pro 2000-MR load. If an AR15 with an adjustable gas block, open it up a half turn and see if that helps.
The simple answer is it is under gassed.
Rocketvapor
Gold $$ Contributor
Have you considered over gassed and buffer/carrier bounce?
Just tell everyone you are shooting your 224V gas gun in short range bench rest and you'll fit in better
Just tell everyone you are shooting your 224V gas gun in short range bench rest and you'll fit in better
Some powders do not produce as much gas as others. Sounds like the pro-2000 may be one of those powders. Could also be the gun is right on the edge of being under gassed. Could also be some one has added too much weight to the bolt or buffer. Or added a super strong recoil spring. Does the gun have a added on bolt release? They can cause the same symptoms. Any fancy non-mill spec parts can cause problems. A new build could be any thing. You do have the gas rings gap spaced correctly?
Frank
Frank
I shot a similar cartridge in an AR years ago. It can be finicky. First thing, pick one powder and stay with it. If possible, pick one bullet. Get the rifle working by adjusting the powder charge, and then go shoot and have fun. It is not the platform to try all the different bullets and powders unless you like to trouble shoot the problems you are having.
If you have a non adjustable gas block, and it still fails to lock open, it is either under gassed or has gas leakage somewhere in the system. It should lock open with those loads.
I have a 223 AR which haa a very conservatively sized gas port. It would run fine but not lock open with 50-55 gr loads, but lock open with 75 gr loads. This was even with the adjustable gas opened all the way up. It turned out I had bought a budget adjustable gas block, and it was leaking around the gas tube. There was an obvious abnormal amount of powder residue leaking around the gas tube.
Switched to a VLTOR block which clamped much more securely and didn't leak around the gas tube and VOILA all problems fixed.
I have a 223 AR which haa a very conservatively sized gas port. It would run fine but not lock open with 50-55 gr loads, but lock open with 75 gr loads. This was even with the adjustable gas opened all the way up. It turned out I had bought a budget adjustable gas block, and it was leaking around the gas tube. There was an obvious abnormal amount of powder residue leaking around the gas tube.
Switched to a VLTOR block which clamped much more securely and didn't leak around the gas tube and VOILA all problems fixed.
Thanks guys. An adjustable gas block and sticking with a specific bullet powder works is where I'll go with it,
I would recommend opening up the gas port. At this point adding an adjustable block gains you nothing. You are at 100% has flow with that port now. Open it up and then choke it down with the block. I'm running over two dozen AR uppers on flavors from 17 to SOCOM. Almost all have an adjustable block. I learned this lesson with a 20 Tactical I bought with borderline gas flow.
Although I agree that he should be running 100% flow with the stock block...I've seen a bunch that either leaked or wasn't installed properly and was partially blocking the port.
If it was mine, the first thing I'd do is install a quality adjustable gas block.
I'd have sorted out the potential leaking first. That's the cheapest and easiest route to start. I'm getting gas blocks direct from the manufacturers who are friends of mine. That does help the pocketbook. I've never fixed a marginal operating AR by merely a block swap.
I'm assuming that rifle cycles fine with both powders, and issue is only on last round hold open.
> If it runs clean, reliably pickup and loads next round, and has no tendency to jam or misfeed then there is sufficient gas volume.
If it is reliably feeding from the magazine, but the BCG isn't holding open after the last round then this can indicate excessive over-gassing &/or inadequate buffer system.
> In this situation the BCG gets thrown rearward and the buffer system *buffer weight & spring) are inadequate to slow down the BCG. In a milli-second the BCG slams to rear of buffer tube and then gets flung forward so fast that it skips right over the Bolt Latch, which may/may not have had enough to be engaged (pushed upward) by the follower in the empty magazine.
> Tail-tail signs of this is the face of the buffer weight will appear very rough and possibly gouged from being peened by the tail-end of the BCG. Other signs/damage may include the post on the Buffer Retainer Pin being bent on angle or snapped off from force of impact of BCG. If this is happening this type of damage shows up pretty quickly.
> If it runs clean, reliably pickup and loads next round, and has no tendency to jam or misfeed then there is sufficient gas volume.
If it is reliably feeding from the magazine, but the BCG isn't holding open after the last round then this can indicate excessive over-gassing &/or inadequate buffer system.
> In this situation the BCG gets thrown rearward and the buffer system *buffer weight & spring) are inadequate to slow down the BCG. In a milli-second the BCG slams to rear of buffer tube and then gets flung forward so fast that it skips right over the Bolt Latch, which may/may not have had enough to be engaged (pushed upward) by the follower in the empty magazine.
> Tail-tail signs of this is the face of the buffer weight will appear very rough and possibly gouged from being peened by the tail-end of the BCG. Other signs/damage may include the post on the Buffer Retainer Pin being bent on angle or snapped off from force of impact of BCG. If this is happening this type of damage shows up pretty quickly.
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Coyotefurharvester
Silver $$ Contributor
If it cycles it is NOT under gassed.
Rocketvapor
Gold $$ Contributor
I set up an AR for the wife, slow fire prone, with minimal gas. Dribbles case out maybe a foot or so. Cold days or lower loads it might not lock back. Open a click or so.
That's fine for prone, single loading.
That's fine for prone, single loading.
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This..it is easier to choke down the gas with an agb or buffer/spring combo...not so much the other way around.
I had a proof 6 arc that exhibited the same issues..some would cycle some would not..some would lrbho some would not. Opening the gas port a bit ensured all would cycle and lock back as should.
The general assumption is that there isn't enough gas, but it can also be that there is too much gas. Do you know if PP2000 generates more or less gas then RL15?
Before you start putting a wrench to your rifle to mess with gas block &/or gas port eliminate one variable. The quickest and easiest way to identify the issue is to swap receivers with a 2nd rifle. First, test the "Upper Receiver in Question", including its BCG, on the second rifle's lower receiver to see how it performs using the ammo loaded with the PP2000 powder. If it function normally then this would indicate the upper receiver is getting sufficient amount of gas.
Second, place the 2nd rifle's upper on the "Lower Receiver in Question" and see how it performs with same PP2000 ammo. If it has any feeding issues then points to the buffer system setup.
I don't monkey with gas port / gas block until after doing the Receiver Swap. Good Luck
Before you start putting a wrench to your rifle to mess with gas block &/or gas port eliminate one variable. The quickest and easiest way to identify the issue is to swap receivers with a 2nd rifle. First, test the "Upper Receiver in Question", including its BCG, on the second rifle's lower receiver to see how it performs using the ammo loaded with the PP2000 powder. If it function normally then this would indicate the upper receiver is getting sufficient amount of gas.
Second, place the 2nd rifle's upper on the "Lower Receiver in Question" and see how it performs with same PP2000 ammo. If it has any feeding issues then points to the buffer system setup.
I don't monkey with gas port / gas block until after doing the Receiver Swap. Good Luck
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