Howdy experts, got another question.  Here's the situation:

was shooting my 20" RRA A4 the other day, some Win white box, lots of Wolf polymer stuff.  Put about 300 rounds thru, give or take, with one or two magazines of relatively quick fire.  (not bumpfiring, just a steady pace)  

Lo and behold, about halfway thru a magazine of Wolf, I pull the trigger and no bang.  Thinking I merely have a bad round, I wait half a minute to see if the round will cook off, then yank the charging handle.  Much to my dismay, the charging handle would not move.  I tried several times to move the handle, but to no avail, all I get is about 1/4" of play, the bolt is rotating a bit, but will not unlock fully.  Since the weapon isn't cocked, I spend a few minutes wrangling the upper off, and summon a gunsmith.  (luckily there was a retired Amry Armorer shooting at the range that day that had a working knowledge of AR15s.)  He examines the upper for a bit, the proceeds to whack the bolt open from the underside of the upper with some sort of nylon mallet.

Upon unlocking and moving back, the bolt promptly ejects a very normal looking fired case, with no unusual extractor marks.  We pulled the bcg apart, but apart from being dirty (from the Wolf) I did not see anything wrong.  The armorer told me my cam pin had a rough spot (I've looked, and I really can't confirm this, it's smooth to the touch along the sides) and had twisted just enough to jam the bolt shut.

SO, two questions:

1)  is this a likely cause for the behavior my rifle exhibited?
2)  can further problems be cured by replacing the cam pin with a different one?

I have not fired the rifle after this incident, although I did clean it thoroughly and cycle two magazines of ammo by hand with no problems.

How closely did you examine the spent Wolf casing? OAL, diameter, etc...

I didn't mic it or anything, I just compared it to another spent casing.  The OAL and mouth size were very close (couldn't see a difference) when I held them together.

Don't change a dam thing on the rifle!!!!!

First off, wolf ammo burns dirty.  Not only gunpowder dirty, but the polyurathane on the case gets slighty scrapped, and this adds powderized poly fouing to the chamber walls as well.


If given a chance, the rifle will self polish/break in all by it's self when feed brass case ammo. On the other hand, if you going to run wolf ammo, then you will find that a little extra CLP on the upper bearing surfaces will help to cut down on the stuck cases (your still going to have them every once in a while with wolf, so we may as well cover the drill.


Round fires, but case is stuck in the chamber (same drill as a unfired round, but don't shove a rod down the barrel is the bolt comes back without the round),

Pull downward on charging handle while giving the butt stock a blow to grassy ground.  This butt stock impact will give the charging handle the extra bit needed to get the bolt back.  If the spent case comes back with the bolt, then great.  If not, then lock the free'd bolt back, insert a solid cleaning rod down the muzzle until the end rests on the back of the spent case web, and give the end of the rod a good pop to drive the stuck case out of the chamber.  Now before you go buck wild and start shooting again, pull the B/C and give it a new light coat of CLP and work/charge the new lubed B/C in the rifle a few times before reloading.  The CLP will migrate in the action and help clear the burnt and powderized fouling that caused the jam.

Note: if you do not have a A1 or A-2 stock on the rifle, then get the stock back in so the blow to the bottom of the rifle is on the receiver extension, and not on the edge of the butt plate which will crack it.

Just a further note to Tweak's picture. If you have a collapsible stock, make sure it is fully collapsed (shortest) position before you do this. There is a small chance you might damage the stock.

Thanks guys, ya'll are the best.