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Posted: 11/27/2004 5:33:25 PM EDT
| I am not near this point in my build, but I am curiouse how do check/ajust the headspace? I am building a Bulgarian AK (5.45x39.5). |
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Toten Kopf has put together a few guides with pics for some common AK building tasks. Here's a link to download his .PDF document showing one method for checking headspace on an AK. www.gunco.net/forums/showthread.php?t=2557 |
| Yeah, the kit I bought from K-VAR... well they messed up the rivets, they didnt drill off the head centered, so it is VERY hard to tell where the rivet shaft is. So that threw my original plan of drilling out the rivet and picking out the remaining and then taping threads. So I bought two practice barrrels and trunnions from kvar and managed to get the trunnions apart from the barrels and now I have two very nice trunnions and one on my kit that is total crap. |
Mind posting that for us here, I don't have an account there so it won't let me view the pdf. |
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get the headspace gauges. I have not headspaced with gauges yet ,but I intend to before I fully assemble the kit.I have a matching barrel and trunnion that I used. I stopped just a hair short of lining the the holes up... used a steel cased round and a brass case round to see if the bolt would close and eject both differant rounds. It did both. I then asked on another forum about then pinning , most of the replys I got, were to line up the holes since the trunnion and barrel match and everthing SHOULD be ok. I then, lined up the holes , pinned the barrel and checked with live rounds to see about closing and ejecting...guess what ..wouldnt close on the brass case, but the steel was ok... I need to use the gauges.. I think useing the gauges is the prudent thing to do when assembling firearms... I do feel it is possible and have heard that some rifles are not headspaced correctly from the get go. |
Where can you get the guages? I had no problem finding gauges for 7.62x39, but I am having one hell of a time trying to find gauges in 5.45x39.5 . I did find one set but the guy wanted $150 for them . I know they are hard to find but damn thats a lot of money. Anyone know of a site that has them?How can you ajust the headspace? if it is dependant on how the barrel and bolt face meet, doesnt that pend on how far the barrel is in? Doesnt the Big Ass pin (trunnion/barrel pin) keep you from moving the barrel in or out? |
| AK Headspace PDF from gunco.net : home.swbell.net/o1ooo1o/akheadspace.pdf |
| Unless you're trying to build out of a total POS then I doubt you would have to replace the barrel. If its a new barrel just press it to where it is in the right place. If it will close on the nogo then press it in further till it won't close. If it won't close on the go gauge then the barrel is in too far and move it back. When its in the right spot drill and pin it. If its a barrel that has been pinned before press it in till its in the same place as it was before. Then if it won't close on the go gauge you'll need to remove some of the material on the back of the locking lugs. If it closes on the nogo you will need to press it in further till it won't and redrill and use an oversized pin. |
Headspacing isn't just for determining if a round will feed or not. If the headspace isn't set correctly you will potentially have a lot higher chamber pressures than what your rifle was designed to handle when you touch off a round. If your rifle explodes in your face and kills you because the headspacing was not set correctly you'll have a lot more to worry about than whether or not your case was ejected. |
Too high chamber pressures? I allways thought it was either the action wouldn't close (too short headspace), or you get a KB (too long a headspace, meaning part of the casing is neither in the bolt nor chamber, and said casing bursts). |
I suppose chamber pressure isn't the right term. What I was trying to get at is that the result of shooting an incorrectly headspaced gun could be disastrous whether it's too long or too short. It's not just about reliable functioning. |
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A couple of articles from Brownells www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=1&i=41 www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=1&i=57 |
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