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Posted: 11/29/2008 3:42:07 AM EDT
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I've developed a feed problem after a repaired extraction issue. I have about 1000 rounds through my Bushie M4 without issue. But yesterday, I shot some crappy ammo I got cheap...Wolf 62gr FMJ. First mag was OK, A few rounds into the second mag, I had a failure to extract, which jammed the next live round into the base of stuck case. I got the mag out, used a rod to tap out the spent case. I checked the extractor which seems OK. Now I get feed jams on the right feed ramp every third or fourth round. It's always on the right side. Tried different mags, Colt and Bushie.
I can't figure out how a cleared extraction issue has caused a feed problem. Could I have screwed up the feed ramp somehow? I've cleaned the chamber and barrel extension as best I can, but still no joy. Any help is appreciated. |
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First off, the Coated wolf ammo is going to have powderized polyurathane fouling (caused by the case being scrapped off surfaces as it being loaded) as well as the standard burn fouling as well (more so since it uses a triple base powder).
The standard powder fouling can be cleaned with any solvent, but the polyurethane fouling will be no be effected by such solvents (short of acetone), and has to be scrubbed out by hand (read chamber brush). Also since we do have powderized poly fouling to deal with using this ammo (read spent case has a better retention on the chamber wall during extraction), often the extractor spring needs to be better tensioned. This can be solved by installing a #60 O-ring around the extractor spring, or changing out the spring to a stronger unit. In your case if you are going to run the Wolf ammo, run the upper bearing areas more lubed with CLP (wont do a thing about the powderized fouling, but will cut down on the other moving part friction against each other), and install the O-ring to help correct the problem. As for the reason that I state to help correct and not cure, sooner or later the powderized fouling is going to get to the point in the chamber that you do stick a spent case in the chamber. When this happens, standard clearing drill of pulling on the charging handle while give the butt stoke off the ground to get the bolt locked back open, then a once piece cleaning rod down the muzzle to eject the spent case from the chamber. Again if you missed it, you have to get the bolt unlocked first, then you can remover the spent case. The cleaning rod down the barrel is not going to unlock the bolt, no matter how hard you pound at it. And to wrap it up, once you do start having problems, it's time to chamber bush clean the chamber throughly!!!! |
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Thanks for the replies. I have no intention of shooting any more of this crap in my rifle. I have 230 rounds of it for anyone in San Antonio who wants to trade for...anything!
My bolt was NOT locked closed. It opened and tried to feed another round. At first I figured that I had broken an extractor, but I guess it just slipped off the steel case. The chamber has been cleaned as best I can get it for now, I broke my chamber brush and can't get a new one until next weekend. Meanwhile, with everything fairly cleaned, why am I getting a feed jam at the ramp when manually cycled with new ammo? The bullet isn't even making it to the chamber. Is there any way that my extraction problem has done damage so as to create a feed problem? I'm totally lost as to where the feed problem came from. |
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Before you do anything, get the poly fouling out of the chamber via a chamber bush. Could be that the fouling left is taking it's toll, even with the brass case ammo (spent case semi sticking and causing the short stroke.
Now if correct cleaning and CLP lubing does not solve the problem of short stoking alone (O-ring will still help with dropped spent cases left in the action), then lets take it a bit farther. Also while you are cleaning, check the key bolts to confirm that they are still tight (37inlbs). Could be that one of both of the bolts have come loose, or snapped, and causing a short stroking problem (bolt not locking back after last shot out of the mag). If the B/C is coming to a stop with the round tip at the feed ramps (no spent case in the action and the bolt behind the rim), then either the rig is low feeding (tip of the bullet striking below the feed ramps at the upper receiver, and you will have dents just below the feed ramps on the upper to show this), or the firing pin collar is catching the hammer. In the case of low feeding, and you have weeded out through the above items such as cleaning and checking the key bolts, try pulling the mags apart and give then a good CLP cleaning as well. In the case of the bolt on top of the case at B/C stoppage, then either the rifle is short stroking (bolt never making it past the rim of the case on the rear stroke), or the mags are not recovering in time. Really, as long as the bolt is locking back at last round, then it's all mags that needs to be cleaned. Now lets talk about the firing pin collar. When the FP is seated against the back of the carrier, the collar edge of it should be slightly below the carrier ramp edge. If you find that the collar is now higher or peened, then you need to reduce the diameter of the collar to prevent it from catching on the hammer during the forward stoke. A drill and file is quick way to spin file the OD of the collar down (chuck the drill up on the ass end of the FP and only reduce the collar just enough to sit ever so shorter than the carrier ramp). P.S. as long as the spent case is being ejected correctly, the ejector and extractor are working fine (read spent cases ejected about 5' to 7' out). |
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