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9/22/2017 12:11:25 AM
Posted: 5/26/2003 5:49:46 AM EDT
took out my target gun which has been sitting for a couple of months, bushy FTupper/lower, blackstar 20" heavy barrel, MK trigger, leupy scope and FF tube.

Punched the bore but did not lube anything as i always put my ARs up wet with CLP.

While shooting i noticed what seemed to be a hesitation of the bolt going home like it was sticking at a certain point. Then the FTFs started with the new round laying on the ramp with a big dent from the bolt slamming on the side of it. My groups started opening up which i figure was from inconsistent bolt lockup. 2 different mags shooting win white box and blackhills blue box 50g HP.

I figured that the gas tube might be catching on the carrier but after breaking it down saw no evidence of that. Thought that fancy solid FP retainer might be dragging since its kindof loose but no evidence of that either. Bolt and carrier looked sufficiently lubed. Cleaned it and it easily passed the 45 deg test (the bolt goes home with the action at a 45 deg angle from gravity alone).

BTW this rifle shot a .86 5shot group the first time out with blue box blackhills ammo.

Any ideas?
Link Posted: 5/26/2003 7:53:16 AM EDT
Similar accounts of working AR's that suddenly don't have been broken or loose carrier key screws. The staking can hold the head in place and make it appear ok. Take an allen wrench and try to tighten them. A rough or sticky chamber can also suck up energy that should go to cycling the action. Examine the chamber and spent cases. This can be associated with the extractor tearing a piece of the rim off.
Link Posted: 5/26/2003 9:40:30 AM EDT
I checked the carrier key for looseness and it was fine. I don't think its a chamber problem as i haven't had any problems with this gun before..anyway i didn't keep any of the cases and the chambe looks spiffy. Its odd cause the gun started out for the first 10 rds or so fine, tho i did notice the hestitation. Then i started getting a FTF every other round or so and then every shot with my group opening up.
Link Posted: 5/26/2003 2:28:25 PM EDT
[Last Edit: 5/26/2003 2:31:09 PM EDT by Dano523]
Pull your mags apart and clean them with clp. The only time that the bolt can dent the sides of the round is when the round stays low//sticks in the mag and the bolt is able to get over the top, instead of forcing the mag out from the rim. Also, clean the hell out of your chamber, including spinning a 30 cal mop soaked in copper solvent. The last MM of chamber cut, at the end of chamber cut right before the throat can get packed up. This will cause the round to act/show signs of high pressure and cause the rifle/action to short stroke.
Link Posted: 5/27/2003 5:05:11 AM EDT
Well i'll give these ideas a shot but the mags i used are my standard range mags that i use in all of my ARs so it seems unlikely that they both would crap out simoultanously. I always use a chamber brush when i clean so i don't think its copper fouling but i will definately give the chamber a better going over. Thanks.
Link Posted: 5/27/2003 10:25:16 AM EDT
I all most missed it, you said bushy. Check the key screws, Bushys have been know to be loose from the factory. The keys screws should be tight (30 inch lbs). The short stoking could have been from a gas leak, and the hesitation could have been the tube entering the key off axes.
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