Malfunctions shooting w suppressor. Ideas?

[colorider]

Ugh. Just got my supressor and am having consistent jams.spent casing is being ejected. Next round is jamming. Bolt is not catching the end of the case. It is going over the case and catching it in the middle and jamming the round. Bolt stuck on top of the round and tip of round cockeyed in the first part of chamber. Big dent in round where bolt is jamming. Like a stovepipe jam but w the bolt not on the rear of the round but rather riding on top of the round Gun runs perfect without the can. Here are the specs
lmt factory upper 556/223 carbine. Aac can. Lower has h2 buffer and tubbs spring.
Everything clean and lubed well
magpul mag
Pmc ammo 223
consistent malfunction w can. Perfect without

Things I changed and results
more lube. No change
less lube. No change
heavier t3 buffer. Worse. Jammed more often
different bcg and bolt. No change
Different lower w a standard spring and t2 buffer. No change
Different mag. No change

changed ammo to freedom munitions 223. 30 rounds and NO MALFUNCTION!

Can a can be ammo picky? Any help is greatly appreciates as I am stumped and also a noob to suppressors

[J]

Most likely cause: The extra gas from the can is causing the bolt to cycle too fast, faster than the mag can raise the next round into position.. I'm honestly surprised the T3 and mag change didn't fix the problem, let alone make it worse. For giggles, have you tried a standard weight buffer?

The can isn't ammo picky. But if it is causing the system to be overgassed, a round that produces more gas will cause the problem to worsen. Have you tried Mil M193 or M855 5.56x45? I suspect they will be worse as they are definitely hotter than the PMC 223Rem stuff.

Have access to a high frame rate video camera? I would bet you are getting some bolt bounce from the pressure.

The other thing that might normally cause this is being undergassed. The bolt not coming back all the way to get behind the cartridge rim. But this would be EXTREMELY odd to happen suppressed and not un-suppressed, as the can should direct more gas through the system. To rule this out, does it always lock back on last round? The bolt has to go further back to get empty mag hold-open than it does to reliably cycle. So if it stays open on last round perfectly, we can rule this out for sure.

[275RLTW]

.223 Rem ammo is less pressure than 5.56 NATO. He is undergassed. The freedom munitions must be a little hotter.

[J]

It typically is lower pressure, yes. I included that in my reply. There are some 223 loadings that may be hotter than some 5.56 loadings, but not too many. Especially the PMC stuff, it is pretty weak from my data gathering (~12% more drop over M193 @500M)

However there is no way that I can imagine where it would have enough gas shot loud, then have too little gas with the same ammo shot suppressed. He should have more pressure suppressed all else being equal.

[colorider]

Heavier buffer= slower cycle. Heavier buffer caused the malfunction every round.
on occasion it has had problems locking back on last round. Thinking maybe under gassed

[J]

But this same ammo works fine when there is no suppressor?

The suppressor should only increase gassing, not reduce it. Unless something else changed too.

[DangerLee_Industries]

Bring it on over pm sent...

[colorider]

Yep, ammo works fine w no suppressor except for the occasional no bolt hold back on the last round. W suppressor I get the malfunction. Heavier buffer made it malfunction every round instead of about every 2 or 3. Colorado hack has offered to take a look and set it straight. Going to make the trip south to have him check it out. Wil report back next week. Prob mid week.

[colorider]

Just got a chance to read this again and also do some reading over the weekend. Overgassing with a suppressor symptoms seem to be exactly the problem I am having. Maybe the freedome munitions stuff is actually less power then the pmc? With the pmc the H3 heavier buffer absolutely made the jam every round. I was totally bummed because all the reading I did said that the heavier buffer should solve the problem.
At any rate, me and the gun are heading south to see Co-hack on wednesday to see what he can find. I fully understand that the suppressor causes a lot more pressure in the cycle and I can actually feel the recoil difference. So maybe it is overgassed and we need to put a cinder block for a buffer. Or maybe an adjustable gas block. Just kind of being frustrated and scratching my head about all of this. Was hoping the supressor was going to be a plug and play type of thing.

On another note, I have a midlength upper, standard spring and t-2 buffer that is getting the 51t brake installed on Wednesday. Will see how that setup does with the can installed.

[MarkCO]

Yes, J got it correct from the start. PMC and Freedom Munitions ammo are lower pressure than most which is why with less gas, it is running. The suppressor slightly raises the gas port pressure and increases the dwell also. Significantly overgassed will also, at times result in a failure to lock back on the last round.

You can go with an extra power buffer spring or adjustable gas. Adjustable gas is just a PITA as it will change over time and once you have a few thousand rounds through, no longer adjustable. The SLR blocks seem to be getting the good reviews right now, but I have not tested one. Noveske switchblocks are bombproof, but a lot of coin.

[colorider]

Sounds like a fox shock as a buffer spring is in order. Lol. Ugh

[colorider]

Met with Tim at DangerLee yesterday morning. GREAT GUY!. Went through several troubleshooting scenarios and and some rounds through the gun. Determined that a heavier buffer with a full auto bcg was a solution to start with. Looks to be working great.!!!!!! However, the gun hates 20 round pmags filled with more then 10 rounds. Shoots 30 rounders perfectly. It jamms with any more then 10 in a 20 pmag. Sooooooooo. Time to look into why. Initial findings are the 2o round pmags get sticky and don't operate smooth when the follower gets toward halfway down. I have spent the last hour trying to figure out what is causing this. Have swapped the green followers out of a 30 into a 20 and it still does it. When you push the follower down on a 20 with a screwdriver, you can totally feel where it gets Sticky at about the half way mark. Something inside is rubbing, or the spring is a different size, or the width on the interior is smaller on the 20s. This could easy explain why the problems with a supressor and the bolt moving faster with the higher pressure. The mag is not feeding the rounds fast enough. Going to be interesting playing with the mags and seeing what results I get. I have always had a problem with the 20 rounders holding back on the last round with 2 rifles.
I shall report back in the magazine section with my results and findings. Thanks again to Tim at DangerLee for your expertise and conversation!!!!

[Gunner]

Met with Tim at DangerLee yesterday morning. GREAT GUY!. Went through several troubleshooting scenarios and and some rounds through the gun. Determined that a heavier buffer with a full auto bcg was a solution to start with. Looks to be working great.!!!!!! However, the gun hates 20 round pmags filled with more then 10 rounds. Shoots 30 rounders perfectly. It jamms with any more then 10 in a 20 pmag. Sooooooooo. Time to look into why. Initial findings are the 2o round pmags get sticky and don't operate smooth when the follower gets toward halfway down. I have spent the last hour trying to figure out what is causing this. Have swapped the green followers out of a 30 into a 20 and it still does it. When you push the follower down on a 20 with a screwdriver, you can totally feel where it gets Sticky at about the half way mark. Something inside is rubbing, or the spring is a different size, or the width on the interior is smaller on the 20s. This could easy explain why the problems with a supressor and the bolt moving faster with the higher pressure. The mag is not feeding the rounds fast enough. Going to be interesting playing with the mags and seeing what results I get. I have always had a problem with the 20 rounders holding back on the last round with 2 rifles.
I shall report back in the magazine section with my results and findings. Thanks again to Tim at DangerLee for your expertise and conversation!!!!
Tim is a good guy, knows what he is doing and a huge help. Glad to see you got it fixed