ps90 cycling problems with suppressor

[john/houston]

[i am new to the forum so i hope that this is not a stupid question, i have a sbps90 and i just installed qsm .223 silencer(through adapter). i am having jams and miss feeds very frequently(1 per every 5-10 shots). gun is clean and i am using ss195 ammo. if i remove the silencer gun functions fine . please help any ideas whats wrong.....thanks john pr=darkred][/color]

[hs338lapua]

What barrel are you using? I had some problems with a cmmg barrel that was tearing up the 5.7 brass. I would look at the spent casings and see if they show any signs of damage.

I called cmmg about the problems I was having (similar to yours), I told them that the chamber of the barrel seemed to be damaging the brass. Their reply was that they had built thousands of the barrels and never had a problem. The gentlman I spoke to told me to get a chamber brush and chuck it up in a drill and spin the inside of the chamber.

Why should I have to do this because they had a problem on one of their barrels? After asking for an exchange mulitple times they finally agreed to send me a new barrel.

I have purchased alot of money worth of firearms/parts from cmmg over the years but after the problems with this barrel and 2 ar barrels I will not buy from them again. Hope this info helps.

[Illuminated_one]

Maybe the suppressor is causing enough back pressure to make the cases stick?

How much play do you have in your barrel/receiver?
Maybe the weight of the suppressor is causing the barrel's chamber face to be off square with your bolt enough to cause trouble?

I'm out of ideas after that

You can try www.PS90forum.com or www.fivesevenforum.com, they specialize in the PS90s a little more.

Does the SS197 also give your problems?

Good luck, and let us know what you find out. I've been considering SBRing and suppressing my PS90 too.

[john/houston]

thanks for the replies....barrel is a cmmg....can is titanium(Jay @Quick Silver Manf.)....i wouldnot think weight of can is an issue, but i agree that there is likely increased chamber backpressure ...the misfed rounds have the bullet "pushed in" the cartridge...really strange looking...anyway will go to ps90 forum and inquire....will keep you informed with solutions...hope this wont happen to any one else!...what a pain particulary since i luv the gun!....john

[Mongo]

You must understand how the P90 works. It is a blow back action so when the case is being extracted the pressure is still very high. This is why the should is blown out forward on the cases. Now when you add a suppressor to the gun you get high back pressure, well if the chamber is not very smooth most likely it will cause extraction issues since it is not trying to extract at higher pressures and the brass is pressed into the walls of the chamber more tightly.

[Illuminated_one]

I agree Mongo, but that shouldn't cause feeding problems too.
Or are the new rounds just hitting the jammed spent cases?



Maybe you could fix the problem by adding a little weight to your bolt? I don't know where you would have room to put it though.
If the bolt weighs more it should delay the blow back some, hopefully until the pressure drops.


I just read your post on PS90forum, and the fact that SS197 does it less frequently confirms that it is probably pressure related. SS197 I believe runs at a lower pressure.

[Mongo]

I agree Mongo, but that shouldn't cause feeding problems too.
Or are the new rounds just hitting the jammed spent cases?



Maybe you could fix the problem by adding a little weight to your bolt? I don't know where you would have room to put it though.
If the bolt weighs more it should delay the blow back some, hopefully until the pressure drops.


I just read your post on PS90forum, and the fact that SS197 does it less frequently confirms that it is probably pressure related. SS197 I believe runs at a lower pressure.

Was not my post on ps90 forum, not a member there.

[Illuminated_one]

Sorry, I meant that last bit for the original poster.

[Fargo]

I am also having issues. First 50 rounds no problem. After the gun gets hot it starts to jamb every couple rounds. Let it cool down and take the suppressor off, runs like a champ again. Totally frustrating.