Suppressors Issue running POF308 Carbine (16.5") w/ TBAC 30P

[Oleshep]

I was running my POF308 Carbine 16.5"bbl with my TBAC 30P for the first time last week and I was having some issues with Stovepipe jams. Now these are not short-cycle stove pipes. The BCG cycles completely and pulls the next round from the mag but since the spent case has not cleared the ejection port the new round is jammed up underneath the spent round. This cause quite a bit of deformation on the new round. This is with the Gas Block set to the low gas suppressed mode, but I also so the same problem with it running on Full Gas... This leads me to think that I still have too much gas and the Bolt is running too fast?

I took the Gas Block apart and everything looks good. also the BCG, Extractor and Ejector all look good and function as expected. I was getting this with both Cold and Hot loads.

Anyone else see this type of problem? I am going to call POF today to see what they say..

 

[RickyRodney]

try a different buffer

 

[Guest]

Give POF a call. They have been very helpful for me and will take care of any issues.

 

[jasonfaz]

Thats exactly what it is. The mid length gas position on a 16.5 is tough on timing when you are running suppressed. It's borderline too much dwell time. A heavier buffer or adding weight to the carrier via a Tubbs CWS is a good fix for the issues youre having.

 

[jasonfaz]

One other option would be the JP SCS if youre running a std length (7") buffer tube. I have one in my POF - also suppressed - and it runs flawlessly with the 110# spring in it. Im running a 12"er though, so you might not need that much additional tension...

 

[Oleshep]

Give POF a call. They have been very helpful for me and will take care of any issues.

I sent POF an e-mail and they did get back to me quickly. They said they had a stiffer ejector spring they can send me. They also requested a Picture of the gas plug and video of the F2F.

I was at the range last weekend and took some videos. I think the problem only happens with my PMAGs but I am not 100% sure.. Maybe the plastic feed lips create more drag on the BCG? I have not gotten the problem to happen with Metal SR25 Mags.

In the video I took you can see the case eject but it actually bounces forward and then back into the ejection port?? very odd.

I need to test a few other variables and get back to POF with the data..

 

[Oleshep]

Thats exactly what it is. The mid length gas position on a 16.5 is tough on timing when you are running suppressed. It's borderline too much dwell time. A heavier buffer or adding weight to the carrier via a Tubbs CWS is a good fix for the issues youre having.

Too MUCH dwell time? You mean you think the BCG is staying locked up too long?

 

[Guest]

Ive only ever used 10 and 20 rd Pmags in my P308 without issue.

 

[Oleshep]

BTW thanks everyone for all the replies. I was starting to think my thread was going to die w/o comment. The hiders come through again...

 

[jasonfaz]

Too MUCH dwell time? You mean you think the BCG is staying locked up too long?

Yes, too much dwell time. To clarify, when i say "dwell time" i'm specifically referring to the amount of time the BCG is receiving gas pressure which is determined by the length of the barrel between the gas port and the end of the muzzle. The ML 16.5 runs fantastic unsuppressed, but when you incorporate the back pressure a suppressor adds it could easily screw with your timing. It sounds like the pressures inside your chamber are not subsiding fast enough to allow the case to be properly extracted. It should happen as follows:
1. Pressure subsides (occuring when bullet leaves the muzzle or when back pressure from can subsides to low enough levels to ensure the empty case in your chamber returns to original size and can be extracted)
2. Bolt unlocks
3. Carrier is pushed to rear, pulling empty case out
Ideally you want the bullet to be out of the muzzle AND the pressure to have subsided before the bolt lugs are unlocked. If the amount of time your BCG is resisting pressure is too long - caused by an extended time gas pressures are high which can ultimately be caused by the length of gas port to muzzle being too long - then you will be left with extraction and cycling issues.

POF might be able to swap your piston to help the issue as well which would help in your efforts to regulate gas pressures and grt that puppy tuned up.

 

[Oleshep]

Yes, too much dwell time. To clarify, when i say "dwell time" i'm specifically referring to the amount of time the BCG is receiving gas pressure which is determined by the length of the barrel between the gas port and the end of the muzzle. The ML 16.5 runs fantastic unsuppressed, but when you incorporate the back pressure a suppressor adds it could easily screw with your timing. It sounds like the pressures inside your chamber are not subsiding fast enough to allow the case to be properly extracted. It should happen as follows:
1. Pressure subsides (occuring when bullet leaves the muzzle or when back pressure from can subsides to low enough levels to ensure the empty case in your chamber returns to original size and can be extracted)
2. Bolt unlocks
3. Carrier is pushed to rear, pulling empty case out
Ideally you want the bullet to be out of the muzzle AND the pressure to have subsided before the bolt lugs are unlocked. If the amount of time your BCG is resisting pressure is too long - caused by an extended time gas pressures are high which can ultimately be caused by the length of gas port to muzzle being too long - then you will be left with extraction and cycling issues.

POF might be able to swap your piston to help the issue as well which would help in your efforts to regulate gas pressures and grt that puppy tuned up.

Okay I am picking up what you are putting down and that makes sense.. If this is what is happening then I am not sure a new gas plug with a smaller hole would help too much? It sounds like the heavy buffer might be what is needed...

 

[jasonfaz]

Not the gas plug, but the piston itself. I luckily have no experience with what POF does for folks having similar cycling and/or extraction issues, but i have on more than one occassion heard of POF modifying the piston to better manage pressures via gas run off. I have no details around how they make this happen though. Id just give POF a call and explain the situation and see what they can do or suggest you try to remedy the situation.

 

[TexasGunTrustLawyer]

Try different buffer. That's a start.

How does it run with a can and the gas in the unsuppressed position

 

[Oleshep]

Try different buffer. That's a start.

How does it run with a can and the gas in the unsuppressed position

During my first testing session I had the jam once while running the gun on Full Gas. That was why I was thinking it was too much gas even with the Gas Block in "suppressed" mode. I need one more range session to test a few more things..

 

[Oleshep]

Not the gas plug, but the piston itself. I luckily have no experience with what POF does for folks having similar cycling and/or extraction issues, but i have on more than one occassion heard of POF modifying the piston to better manage pressures via gas run off. I have no details around how they make this happen though. Id just give POF a call and explain the situation and see what they can do or suggest you try to remedy the situation.

Right on. I plan on talking to POF again here after I finish up one last testing session.. Thanks for your help..

 

[TNottingham]

Same problems with my POF 16.5 I put a JP silent capture spring on and it took care of all my problems, that's after I tried two different regular springs.