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Old July 12th, 2021, 08:30 AM #1
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Speaking of AR-15's

I pulled out of the back of the safe the Bushmaster Varminter that I've had forever. I recently purchased, from another MDShooter, a 7.62 x 39 upper and thought I would match them up.

For some reason I can't get both pins back in place with that upper. Which then raises questions for me about the safety of shooting the rifle if the fit doesn't seem just right.

Any ideas? Or suggestions for where I might find someone trustworthy to look at the set up and see what I might be doing wrong?
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Old July 12th, 2021, 08:34 AM #2
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Quote:
Originally Posted by boisepaw View Post
I pulled out of the back of the safe the Bushmaster Varminter that I've had forever. I recently purchased, from another MDShooter, a 7.62 x 39 upper and thought I would match them up.

For some reason I can't get both pins back in place with that upper. Which then raises questions for me about the safety of shooting the rifle if the fit doesn't seem just right.

Any ideas? Or suggestions for where I might find someone trustworthy to look at the set up and see what I might be doing wrong?

What is the brand of the upper? Can you see any visual misalignment?
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Old July 12th, 2021, 09:04 AM #3
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Are either cerakoted? If so, the cerakote can mess with tolerances. Might need a light tap with a plastic hammer.

I have an upper thats off and the front pin hole had a lip on it. I took a light file to the lip and the pin goes in fine.

Small variances like that shouldn't cause issues with shooting. The main issue you'll have with a 7.62x39 are the magazines. Sometimes they don't feed right and the cartridge will hang up. Mine was reaI bad and I had to grind back the feedramps on my barrel extension so the bullet tip wouldn't catch.
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Old July 12th, 2021, 09:06 AM #4
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Old style lower perhaps? Colt had those lowers early early on which had different pin spacing. I don't think Bushmaster did that but I'm not sure
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Old July 12th, 2021, 09:23 AM #5
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Old style lower perhaps? Colt had those lowers early early on which had different pin spacing. I don't think Bushmaster did that but I'm not sure
Colt had different large pin diameters, not different pin spacing. Bushmaster only made standard pin lowers and uppers.

Loose, sloppy AR’s that fall together are less desirable from an accuracy standpoint. There is nothing wrong with the upper/lower needing a little pressure to go together. There are still tolerances for a “milspec” upper and lower. One being on the large end of tolerances, and the other being on the small end of tolerances will make for difficult assemble. Everything can be perfectly safe and within tolerances, and still be hard to go together.


To assemble:
Push the front takedown pin in. Swing the upper down onto the lower. Squeeze the upper and lower together, and push in the rear takedown pin. A light tap on the pin with a soft faced mallet may help, and is ok. If you have to beat on it, there’s a problem. Several of my upper/lower combos need a light tap to assemble, and a light tap to disassemble.
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Old July 12th, 2021, 09:38 AM #6
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Quote:
Originally Posted by GunBum View Post
Colt had different large pin diameters, not different pin spacing. Bushmaster only made standard pin lowers and uppers.

Loose, sloppy AR’s that fall together are less desirable from an accuracy standpoint. There is nothing wrong with the upper/lower needing a little pressure to go together. There are still tolerances for a “milspec” upper and lower. One being on the large end of tolerances, and the other being on the small end of tolerances will make for difficult assemble. Everything can be perfectly safe and within tolerances, and still be hard to go together.


To assemble:
Push the front takedown pin in. Swing the upper down onto the lower. Squeeze the upper and lower together, and push in the rear takedown pin. A light tap on the pin with a soft faced mallet may help, and is ok. If you have to beat on it, there’s a problem. Several of my upper/lower combos need a light tap to assemble, and a light tap to disassemble.
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Old style lower perhaps? Colt had those lowers early early on which had different pin spacing. I don't think Bushmaster did that but I'm not sure
The early AR15/M16s had a larger front pin hole on the upper(and lower) where a screw originally attached the front halves together. This should only result in a loose upper-to-lower fit so this should not be the problem.

Some upper rear pin holes aren't properly elongated and require a bit of fitting.
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Old July 12th, 2021, 09:40 AM #7
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The only thing that really matters safety wise is that the bolt locks on a correctly head spaced chamber.
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Old July 12th, 2021, 12:30 PM #8
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The only thing that really matters safety wise is that the bolt locks on a correctly head spaced chamber.
This.
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Old July 12th, 2021, 12:39 PM #9
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The only thing that really matters safety wise is that the bolt locks on a correctly head spaced chamber.
Hey Doc, I thought your specialty was boobies that are too floppy for small bikinis.....branching out now are we?
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Old July 12th, 2021, 12:39 PM #10
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Is this the Radical branded upper that was posted on here not too long ago by chance?
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