PCC Blowback system & Dirty Brass

[Cy Soto]

I have a Quarter Circle 10 PCC with a 16" barrel that I put together two months ago.  I have only shot a handful of matches with it (and only one practice session).  I have not had time to develop a load for it but I tried shooting some of the Production loads that I had stashed away and since it seemed to function fine, that is all I have shot thus far (less than 500 rounds). The Production load is 4.1gr of Titegroup under Montana Gold 124gr projectiles (mixed brass).  

The empty cases come out of the gun extremely dirty; almost as if the cases were not obturating.  However, the gun shoots well, accuracy out to 25 yards seems adequate and the bolt locks open on the last shot (with a Blitzkrieg piston buffer and AR-10 spring).  

Is the fact that the brass is so dirty just due to the nature of the blowback system of the platform or is my problem that the loads I am using are too underpowered?  Before anyone asks... Nope; I have not chronoed these rounds out of this PCC yet but they get me 135 PF out of a Glock 34.

Edited December 23, 2016 by Cy Soto

[CZ85Combat]

your loads are not under powered, if anything they are overpowered. your 135pf Glock 34 loads are probably 145pf-155pf or moer in your carbine.

[mscott]

Just the nature of the blowback carbines. I have several loads with different powders with various bullet weights and wouldn't call any of them clean.

[Aircooled6racer]

Hello: It is just the nature of the beast. Load up some of those 124's with 3.3 grains of Tite Group and see how great it shoots. With that Blitzkrieg buffer it should be a soft shooter. That is one of the buffers I want to try. Thanks, Eric

[Bamboo]

^^^ yep, nature of the blow back beast.   Picking up brass after a match you can tell which were fired from the blow back guns. 

Not so worried about the cases being sooty, but it is good to avoid having a lot of crap buildup in the triggerworks and bolt face.  Had some 9mm loaded with AA#5 and HS-6 and it left a lot of dirty grains in the triggerworks.  Shot the last couple matches with fast powders with no to low NG content and it only left a light soot that wiped away easily with a q-tip and no powder grains.   

 

 

[Alvin]

My cases are the same....dirty, but wipe off easily.  I clean the inside of the gun after every match....wipe out what I can reach in the bolt area and in the trigger area and blow out what ever else is in there.  Using 231 for powder at a 135 power factor and 135 bullet.  Runs like a champ!

[Manwithnoname]

I have several different types of blow back rifles to include 9 ARs. On each type the brass comes out dirty. 

[jeepercyr]

I had the same issue with AA#2. Switched to CFE Pistol and it cleaned up considerably.

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[OPENB]

If you can try some single base powders like Solo 1000 or Prima V, you should see a cleaner gun & brass. 

[Cy Soto]

If you can try some single base powders like Solo 1000 or Prima V, you should see a cleaner gun & brass. 

Solo 1000 is a phenomenal choice. I have used it for 40S&W loads with great results.

These days however, it seems to be somewhat difficult to find.

[L9X25]

Solo, that is a name from the past.  I was shooting a 10mm open gun and the only light bullets were 135gr lead SWC.  To make major I needed to push the 135's pretty hard and leading was always a problem.  I kept complaining to the bullet manufacturer and he told me to try some Solo powder.  I found some 1500 (pretty slow) and I could push the lead much faster without causing leading than any of the usual Winchester powders.  The cases would come out of the gun as shiny as if they just came out of the tumbler.  That was great stuff.

Edited June 29, 2017 by L9X25

[MHitchcock]

Dirty brass is a normal side effect of a blowback design. I wouldn't worry about it. It comes out of the tumbler clean.

[NOMADSS]

All blow backs are dirty.  Just need to learn to deal with it, clean often and have cleaning gear at the ready.

 

 

[Rommy]

My son and I have the same PCC 9mm. Mine gets very, very dirty his dose not. If it was becoures of the blowback system Wouldn't the both get very dirty???

[frankge]

no expert on pcc but the psa upper i built intially had a 6.2oz 9mm buffer and as a lefty was getting crap in the face - 4.3 W231 124 FMJ. Went to a 8.5 oz 9mm buffer and no in the face anymore. Think its more how long before the carrier starts to move. Admitted this is not a sooper smancy pcc

Edited January 6, 2023 by frankge

[rowdyb]

^^ but you're right. It's reflective of the dwell time, how sooty your brass is