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Posted: 4/13/2003 5:03:57 PM EDT
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Hey guys, Got a Bushy M4gery, bought new last fall. Had several misfeeds on first day at range, all with the factory 10 round mag and using commercial .223. Bought some USGI 30's and 1K of LC XM193, Lot 7, end of problems. When that was gone, I picked up 500 lot 9, again no issues. Somehow, that ammo disappeared (last seen heading downrange), so I stopped at a gunshow and bought 500 rounds of newer LC XM193, lot #18... Now I have a california legal single shot. About one out of every three shots results in the following: Round half fed, bolt half closed or- two rounds half fed, bolt 1/4 closed or- no round fed, bolt closed or- round half fed, spent brass half ejected, bolt squeezing it all together or- bolt failing to hold open after last round in mag or- some combination of the above, I think you have the idea by now... Went through gun stem to stern, then had an employee and shooting buddy (13 years in the Marines, grunt the whole time, Gulf War vet) go over it... Checked gas tube, extractor, gas rings, bolt carrier, gas key, recoil spring and buffer... Found nothing wrong... After another day of frustration at the range, another buddy commented that the report was very variable: BANG, BANG, bang, BANG, Bang, (click), "@^#%$!!!! Now, sitting behind the dreaded mini y-comp 'o hell, I didn't notice... The other guys we went shooting with all agreed that the volume was all over the place. Seems like the ammo, right? Went to ammo forum and asked about lot #18, was told I was crazy, it was good ammo, I just had a dirty or broken rifle. My past exeriences with LC XM193 would tend to indicate that also... I know, I know. Go get a different brand of ammo and test it. I will try to later in the week, but for know: Does this sound like bad ammo or bad Bushy? Where else on the gun should I check? Help! |
| My AR did the same thing over the weekend shooting up an old washer and dryer. I got it home and noticed the gas key was loose!!! Retightened and restaked (I bought it assembled from bushmaster), good to go the next day ran like a champ. It was barely loose but what a difference it made. |
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Washer and dryer... He he he... Wish I was there. Thanks for the input guys. Yesterday my Marine buddy and I disected the entire rifle again, this time on an embalming table (literlaly, my workshop table is covered with the entrails of a new computer I'm building. Different problems, different board.). Guess what? There IS a tiny bit of play in the carrier key! Didn't notice it before, but I guess I was checking it wrong. Instead of grabbing the key from the middle and wiggling it, I grabbed the end of the tube, and was able to feel a TINY amount of play. Never would have guessed that would be enough to cause problems, but after reading ptaylor's post, that sounds like the fix... New problem: What the hell do I use to tighten it? My army tech manual calls for a "tight fitting 1/8 inch socket head screw socket wrench attachment". I tried a 1/8 inch, hex shaped bit driver from my socket set, and it is way too small. Went through a huge drawer of bits and adapters, allen wrenches, etc., nothing fits it... Also: Could a gas key problem cause the volume differences between each shot? I hope to get to the range this afternoon, and maybe to the hardware store first. Keep you posted. |
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Yes on the leak causing the problems. The allen wrench is a 9/64. Also, when you work on the key, pull it off the carrier and clean up the baked on fouling from the leak. Then use Blue loctite to make a thin gasket between the key to carrier, it will seal any voids. When you reinstall the key allen screws, toque to 35-40 inch pounds, and then re-stake the screws. Note: If you have the time, lapping in the key to carrier is always a good idea, and saves you from having to use the loctite as a gasket. |
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