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Posted: 11/28/2007 8:43:45 AM EDT
| Earlier this year I put together an AKM with a bunch of left over parts I had gathered together along with a 100% receiver. I ended up pressing a Romanian barrel into a Maadi trunnion, assembled it, and everything looked good (receiver cover fit just right with no gaps, etc.) so I went to a local range and test fired it with a 50 ft. lanyard. It fired fine and didn't go kaboom so I thought the headspace was fine. I've since put about 200 rounds through it without a glitch. A few days ago I fieldstripped it to clean and oil it and I noticed the locking lugs on the bolt were starting to mushroom over. I placed the bolt into the trunnion without the carrier and noticed a .040 gap between the bolt face and the breech face. I could easily wiggle the bolt back and forth when it was in battery, and I know this isn't good! My question is how can I fix this? I realize the proper fix is to push the barrel back .040 and install an oversize barrel pin. The only problem is I only have handtools and the barrel pin should be precision drilled with a drill press, also I would have to trim the receiver cover so it would fit back on. If I do redrill the barrel pin where would I get a new barrel pin that would be .080 bigger? Would it be possible to just add a .040 thick hardened shim to the breechface (properly contoured for the extractor) and epoxy it in place? I realize this sounds cheap, but would it work? I guess another solution would be to add .040 of weld to each of the locking lugs on the bolt, but then I could only ever use that one bolt and welding would mess with the original hardness of the bolt. Any help or advice would be greatly appreciated! Phil |
| The weather is cold here in WI, 18 degrees right now! I fit the bolt in there with a cartridge and the play is almost gone now. I don't have headspace gauges, but I suppose I could try the masking tape method (3 layers on the cartridge base is the no-go, correct?) I have fired this rifle with two different bolts and have noticed slight mushrooming on each of the bolt's two lugs. They could have been like that though because I didn't really check them out that close before, it could be preexisting. I took a handfile to one of the bolts just to clean up the mushrooming. I will put about another 100 rounds down the pipe with the cleaned up bolt and then check it out. I'm hoping the headspace is fine and the bolts were just like that from the start. Thank you everybody for your help, this board is great! |
Wow, this is one amazing thread. Advice on the internet is worth exactly what you pay for it but...... I'd do a wee bit more research before I'd pull the trigger on that thing. Brownells has headspace gauges for $25.00 each, that's a cheap price to pay to keep from possibly blowing up your rifle or even worse, blinding or hurting yourself. Regardless, good luck to ya!!! |
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Ditto to this.... "Brownells has headspace gauges for $25.00 each, that's a cheap price to pay to keep from possibly blowing up your rifle or even worse, blinding or hurting yourself." I was remiss in NOT asking if you actually had any gauges. These are the bargain of the Century.... less than 1/100 the cost of an Emergency Room visit. I use gauges on everything - matching kits (3 found excessive to date), NEW rifles (TWO found excessive to date), and my builds (0 tight or excessive - because I build with gauges as I go along). Please - if in doubt? Buy or borrow some gauges from a friend... they are WELL worth the cash. I even have a set of 5.45's... and they have saved me from TWO bad Century SAR2 builds. |
| I've found that the headspace is excessive in this, the bolt will close with 6 layers (3 is max!)of masking tape on the base of the cartridge! I will not fire this again until the problem is fixed. Does anyone know of a source for oversize barrel pins so I can get this into spec? Or should I just push the barrel in to spec, drill a hole, and use a a turned down drill bit? Thanks in advance, Phil |
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Also - only MINOR Excessive HS issues can be solved by oversized barrel pins. You see, the Diameter of the pin has to increase 2X the amount you move the barrel back. Pretty soon? You run out of trunion. If a barrel MUST be moved - and saved? Given gross Excessive Headspace, you must then strip the barrel, weld over the old "Divit", turn the barrel on a lathe to smoothe the weld, then swear like hell IF, at drill time, you need to go thru part of the weld :) I have never done this - and won't. Chris Butler at AK103.com HAS... If you have a BAD problem with excessive HS, please consider dropping him an email if you MUST save the barrel. If you have a MINOR excessive HS issue? Then your plan will probably work. |
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