M-14s vs M-305

Some food tastes better heated up to be honest, but rarely Chinese.

Now that I think about it, Chinese rarely tastes good at all.

So what is going on in here btw?
 
No, SERIOUSLY, I really was eating Chinese food leftovers.

That was not meant as a disparaging comment regarding the rifles.

You guys are awfully defensive!
 
Wow... I just headspace checked the worst Polytech bolt I have ever personally run across.

Machining-wise it appeared nice and had nice even contact on both lugs.

The receiver is in-spec, and if anything, a bit on the tight size as a new USGI bolt would *just* not fully close in the receiver at all. It would have to be lapped to fir this receiver, so the lugs recesses are nice and tight.

The Chinese bolt, however, closed on a GI field gauge and still had at least another 5 thou of wiggle. This was with the bolt stripped.

Rifle was a 2009 Polytech. The receiver is really quite good, but this bolt was almost dangerously undersized. Definitely not a bolt for use with reloads.

Looks like I need to find another GI bolt to get this one up and running properly.
 
Wow... I just headspace checked the worst Polytech bolt I have ever personally run across.

Machining-wise it appeared nice and had nice even contact on both lugs.

The receiver is in-spec, and if anything, a bit on the tight size as a new USGI bolt would *just* not fully close in the receiver at all. It would have to be lapped to fir this receiver, so the lugs recesses are nice and tight.

The Chinese bolt, however, closed on a GI field gauge and still had at least another 5 thou of wiggle. This was with the bolt stripped.

Rifle was a 2009 Polytech. The receiver is really quite good, but this bolt was almost dangerously undersized. Definitely not a bolt for use with reloads.

Looks like I need to find another GI bolt to get this one up and running properly.
I just bought a Poly M305, stamped as M14. It's serial # is also 2009. Any suggestions as to a quick and dirty check on my bolt? I used a new (unfired) casing, ground out room for the extractor and some plastigage. It was about .014" gap. Was going to leave casing length (from shoulder to head) about .007" longer. Will still trim the neck though. Now you have me thinking. Good idea or bad?

From everything else, it seems pretty tight, little to no residues on the neck and case does not look overly stressed or stretched.

I guess I should get my butt over to the Calgary clinic.
 
If you don't have a gauge, fire some factory rounds and send the empties to Hungry - he'll give you a measurement of your headspace.
 
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