Posted: 5/3/2001 6:50:33 PM EDT
the troubleshooting forum? I got a doozy and I guess there is no other place to put it.
OK, I have some other posts about this sort of, but this is the main one after two days of experimentation.
Problem - AR carbine that goes into burst mode. Only three times but that is enough.
Rifle 1 (the one with burst problem) is a frankengun. Wilson 16" bull barrel, freefloat handguards. FN upper flattop, ASA bolt, bushy lower built with bushy parts, RRA NM trigger, buttstock & plunger/spring from SP1.
Rifle 2 is a spacegun 20" douglas barrel, freefloat, flattop, ASA lower and buttstock, Jewell trigger, NM bolt.
The problem started when I was breaking in Rifle 1. I was shooting Federal Eagle ammo. The rifle had two occasions where it burst about 3-4 rounds. While bursting I could feel the trigger pulse with each shot fired. I also fired Q3131A ammo and never had a burst.
Returned to the range a second time, and again, with Federal Eagle ammo it burst once in about 20 rounds. Never again with Q3131A.
Soooo, I thought I would experiment. I swapped lowers with Rifle 2. Expecting that the problem was related to the trigger I tried shooting the Spacegun upper on the frankengun lower. Except it would not cycle. Short stroking. I can only assume that the different tension in the buffer springs prevented a full cycle. However, the Spacegun (which shot fine once reassembled) only eats Federal Match ammo. So I don't know if it would have been a valid test.
At this point I was out of Federal Eagle ammo, and never had a burst again.
The conclusion I have (???) is that the carbine has a powerful buffer spring (can't cycle in spacegun) and that it is slamming the bolt back hard - into fairly soft Federal primers and the firing pin is actually extending when it closes to battery.
If this seems a valid conclusion, does anyone have any suggestions for fixing this? I don't want to worry about which ammo I use in this gun so would prefer an answer other than "don't use Federal Eagle".
That would'nt happen to be the gun that got thrown across the counter would it?[:)]
Thanks for the tips. I am taking it to my gunsmith for a checkup.
No. Well, parts of it are. Maybe the parts have a long memory??? :)