AR Sponsor
Posted: 9/24/2014 9:24:06 AM EDT
|
A buddy brings me his AR last night, says he has had these two matching identical AR's for a couple years and never shot them. They were "custom" made by a "gunsmith" in our area. This is a first for me, I have never had the opportunity to see this before. His bolt closes on an empty chamber. Place round in the chamber, with or without a mag, and bolt fails to close by maybe an 1/8th of an inch. He said he took the bcg out and placed it in another rifle and that rifle fire fine. But the identical, twin AR's both fail to close with round in the chamber. I did not have my go gauge at my disposal and these AR's went back to their home a couple hundred miles away, so not sure I will ever get to examine them again. About the guns, the lowers were marked with the private roll mark of the shop that made them. The barrels had zero markings of any kind, no caliber, no brand, no twist. From what I could tell they were unlined barrels. Unknown if they had been nitrided. I have only been around mostly quality name brand barrels. I have never seen this before, bcg's works fine in another gun but not in either of these. The other guns bcg gives same result in the twin guns, wont close on round. As I have read about this before, I am thinking it is a short chamber. Not having had my gauge present and never really having seen this problem in person, leaves me asking the forum. My advice was to contact the gunsmith who built the guns and find out about the barrel and tell the assembler what is going on with the guns. My buddy had actually been able, with considerable force, to close the bolt without a firing pin present. He wanted to try and I removed the firing pin so he could just because. But it was considerable force and I was seriously concerned the round would eject. It did but the neck of the case ended up very slightly swaged. Just looking for thoughts from people who have seen anything like this. My thoughts were short chamber, but then maybe alternate caliber--but what? With no markings on the barrel and go gauge not in my possession at the moment I am left wondering.
|
|
Quoted: Not really clear how he is chambering a round. Is he using the charging handle and letting the bolt fall properly? or just easing the bolt into battery? You can drop a round in and it looks like it seats but that bolt will not close without major pressure. The kind of pressure where I encouraged him to stop immediately but then it finally closed. The guy closing the bolt is 6'3 and 250. The only way he could seat it was to remove the upper, drop in the round and press on the rear of the bolt carrier.
|
|
Quoted: Out of spec chamber for sure |
|
Quoted: If you are close you can hand ream the last few thou with a finish reamer. Always check with these: http://www.brownells.com/userdocs/skus/l_184000037_2.jpg |
|
NEVER, EVER remove the firing pin to function check. That firing pin holds the cam pin in place, without the firing pin, the cam pin can rotate up and out of position locking up the action like you have never seen before and it can take an act of God and some mighty fancy fishing, cursing, and manipulating to get the damned thing open again. I have even heard of one or two guys who got the rifle so jammed up that they ended up ruining their upper receiver when they 'lost it' and did something even more stupid than cycling the action without the firing pin in there. You were lucky you did not muck up your buddy's rifle big time. I'd say you need to go buy a lottery ticket because good luck is running with you right now.
If you must use live ammo, get a spare firing pin and grind off an eight inch off the end. If you cannot use snap caps, dummies, or a ground off firing pin, leave the damned thing alone. It seems I have read of people doing this two or three times lately and it is going to bite someone in the ass. It is bad enough when you get bit doing this with your own rifle, but when it happens to your friends rifle, your name will be MUD for a very long time and you will rightly earn the reputation that you do not know what the heck you are doing. |
|
Quoted: NEVER, EVER remove the firing pin to function check. That firing pin holds the cam pin in place, without the firing pin, the cam pin can rotate up and out of position locking up the action like you have never seen before and it can take an act of God and some mighty fancy fishing, cursing, and manipulating to get the damned thing open again. I have even heard of one or two guys who got the rifle so jammed up that they ended up ruining their upper receiver when they 'lost it' and did something even more stupid than cycling the action without the firing pin in there. You were lucky you did not muck up your buddy's rifle big time. I'd say you need to go buy a lottery ticket because good luck is running with you right now. If you must use live ammo, get a spare firing pin and grind off an eight inch off the end. If you cannot use snap caps, dummies, or a ground off firing pin, leave the damned thing alone. It seems I have read of people doing this two or three times lately and it is going to bite someone in the ass. It is bad enough when you get bit doing this with your own rifle, but when it happens to your friends rifle, your name will be MUD for a very long time and you will rightly earn the reputation that you do not know what the heck you are doing. |
|
I would suggest tracking down the gunsmith that made them, and see if he can provide any info as to what the rifles are chambered for.
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
AR Sponsor