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Discussion Starter #1
Okay so here is the problem. I recently got my first m-14 type rifle (Polytech M-14S all main components are stock chinese) and I'm worried about the headspace. The problem is it's too tight or at least seems to be. My bolt wont close with just finger pressure on .308(Remington, Federal) or 7.62(American Eagle for M1A) commercial ammo. It will only lock on a full release of the op rod. It'll feed and extract 20 rounds in a row no problem both with my hand operation and while firing. (only fired a few because of obvious concerns)

When I say it will only lock on a full release that's what i mean. Anything in between just doesn't consistently lock it. (full mag always in)(obviously never full release without a mag in and never ever with a round in)

I don't know much about headspace but it seems that a chamber this tight wouldn't leave enough room for expansion.

Really i just want to know if this is some what normal or too tight to fire.
 

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Carl Lesinger is in N Jersey - he could look at it for you.

Or, get a redding body die and bump the necks back a few mils. But, then again: are the rounds too long or too wide?? Figure out where they are binding - black magic marker might work.
 

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Discussion Starter #3
I wiped some washable ink all around the case and when it comes out the only real marks I see are on the neck and the shoulder. The marks seem normal. Seems to be headspace or neck width. Another Odd thing is it always binds in the same spot. Also Up until the bind and directly after the bind it moves freely. Maybe a build up in the chamber?
 

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So no problems with 40 rds? no FTF, with loaded mag in you are supposed to let the bolt fly foward, any less than full stroke may not lock it up, the mag tension on the round takes some of force out of the bolt comming foward, if not all the way back. IMHO


Rocky dance2
 

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Discussion Starter #6
yeah no problems with firing and i know its supposed to come all the way with a mag.

But should the bolt lock if I put one in the chamber and push the op rod forward? (spring off)(medium pressure)

I also cleaned thoroughly when i acquired it as well as after the first range trip. Completely disassembled re-blued a lot of parts and Re-finished the stock when i got it. cleaned oiled greased.

If It seems normal and people who are smarter than me think the pressure isn't a problem then I'm fine with the way it is. I just don't want hurt it thinking its not a problem.
 

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Now with no spring installed, as the bolt closes on a round in the chamber, remember the pressure to get the (spring loaded) extractor over the end of the round, or take the extractor and ejector out, (field strip the bolt) to be sure you have nothing still binding, just to be sure! You can read the stickies on bolt disassembly here, they go picture by picture.


Rocky FRG1
 

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You can go to the stickies link in the top of the Firing line forum listed (stickies link) for all kinds of info

Rocky MCORPS1
 

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won't lock up

What kind of grease are you using to lube the bolt and other areas that need to be greased. My thought start with the simple answers.
 

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The only way to find out if the headspace is too tight is to check it with some HS gauges. However, I get the feeling that if you compeltely disassemble the bolt (no extractor, no ejector or spring and no firing pin) and insert a round into the chamber, the bolt will probably close on the new round freely. The pressure you are probably feeling is the extractor and ejector.
 

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Discussion Starter #11
I did forget about the extractor pressure.

It seemed to me like the round itself moved though. when I slide one in the chamber it also looks to be not quite in enough.

I think it might be a combination of extractor pressure and chamber tightness around the neck. I think there might be some stubborn gunk that needs a more aggressive cleaning in the neck area. Its hard to clean that spot well and i might have neglected it.

If it was headspace i figure it would show more on the shoulder.

Thanks for the comments.
 

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The only way to find out if the headspace is too tight is to check it with some HS gauges. However, I get the feeling that if you compeltely disassemble the bolt (no extractor, no ejector or spring and no firing pin) and insert a round into the chamber, the bolt will probably close on the new round freely. The pressure you are probably feeling is the extractor and ejector.
this is solid advice,you must strip the bolt when chamber checking rds. or head space gauging your rifle.in my short experience w/polytech it is not short and probably long on HS.. just as an aside if you ever replace bolt w/ USGI make certain to gauge HS and firing pin protrusion. also be advised that the locking recesses are on different angle than GI and the best part of polyteh is the rcvr..just trying to keep everyone safe.
 
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