View Full Version : chamber fouling question

September 21, 2001, 17:06
How can you get enough powder fouling in the chamber to stop extraction but little or no fouling in the barrel?He's firing SA ammo.
The last time he brought the rifle to me
instead of destroying the charging handle.
Tried the banging the butt method with no
result so pulled the cover and lower and tapped on the back of the bolt to get it out of battery then slipped a pry between the back of the carrier and the pivot pin housing
That cleared it.The brass has dimples from
the fouling in the chamber.Only fired 30
rounds.I helped him put this rifle together
and I can't find any thing wrong with it.


September 21, 2001, 17:29
Let me guess.

He slammed the bolt on a fired case.

That will do it every time.

Spent cases should not be re-inserted in the chamber without resizing. They are bigger (fatter) than the chamber. The bolt slams with enough force to drive them into the chamber so tightly that it really takes excessive force to extract them.

September 21, 2001, 17:59
No,he just went to the range to shoot.It was just a failure to extract.He had one about 10 rounds prior to the last one but he was able to clear it with the charge handle.He saved that brass for me which had fouling to just below the neck.The last round had fouling half way down the case.I would and did suspect the ammo and him not keeping his rifle clean but there's almost no powder residue in the barrel or gas system.Has a chrome chamber by the way.

September 21, 2001, 22:37
Sounds like this failure to extract was more likely a failure to eject that resulted in the non-ejected casing being rammed back into the chamber.

September 21, 2001, 22:43
I concur with Gary. Last time it happened to me I had to bang the butt on hard ground as hard as I could to eject the case. Took several tries but eventually worked.

September 21, 2001, 23:58
ahhhhhhh - FTX masquerading as a FTE - I never thought of that (mine does this too, from time to time). So now what? What's the troubleshooting procedure for a failure to extract?

September 22, 2001, 02:01
I suspect that Jeter nailed it, as it happens so fast that the cause is overlooked.
If that proves not to be the case you have two other possibilities: an over sized chamber, for which you can determine by making a casting of the chamber using Cerro-Safe from Brownell's, than measuring the dimensions of the casting. I doubt this is the cause, unless a real idiot reamed(cut) that chamber at sometime.
THe other choice is that the chamber isn't quite as smooth as it appears, and needs some careful polishing, using a Dremel fitted with a flexible
Dremel extension-head cable. Even a rough chamber wouldn't explain the powder indentations.
The "Jeter prognosis" has to be the explanation, possibly compounded by
firing ever so slightly out of battery...premature detonation. This is fairly common with worn machine guns.
I'd repair/replace the ejector; and, examine & clean the extractor, as any extractor problem can retard the normal cycling function, causing the ejector to seem defective. Check the extractor for damage, debris, and function(it might be sluggish from burnt powder build-up, or a tired spring).

September 22, 2001, 11:59
Good ideas,Thanks.The extractor and ejector
are fine so I think I'm down to three things.
Chamber,ammo,and gas setting.Has anybody else had problems with the SA ammo?In the ads
they say plinking ammo.A.K.A.poor quality.
The chamber is chrome and I can't find any
rough spots on the fired brass.He doesn't have a hold open yet so will have to go to the range with him to set gas reg.(darn).The
powder fouling combined with a low gas setting which rechambers spent brass sounds like the problem.Thanks Gary,I never would have thought of the rechambering angle.
Will post with results.

September 22, 2001, 12:17
usmc326 you said
"... an over sized chamber, for which you can determine by making a casting of the chamber using Cerro-Safe from Brownell's, than measuring the dimensions of the casting."

Out of curiosity. What would the maximum dimensions be?

September 22, 2001, 13:30
How do you troubleshoot/replace an ejector? Isn't it part of the ejector block? Mine looks OK, are there any minumum/maximum dimensions I should look for?