barrel extension to upper fit and relationship

S

steve garrett

Active member
recently I have been playing with a 10/22 its the first one I have ever owned. They are the ar 15 of the rimfire world. One of the things many people say is that the barrel needs to have a tight interference fit on a 10/22 to ring it true accuracy potential out. so I got to thinking an ar 15 also has a barrel that slides into a receiver however its of course got a barrel nut so its not as big of a deal. so I did some digging on the internet and found Bat machine makes .001 oversize barrel extensions. I also found that BCM makes undersized uppers. I also found a guy that has written some articles and from his testing found that be getting rid of the slope between the barrel extension and the upper he has been able to improve the accuracy on average of about 1/3 rd. he is using 2 menthods to do it. preferable the BAT machine oversize extension. OR he is ordering stainless shim stock and wrapping the barrel extension. then using green loctite to make it all go together.

its typical for me to see some wondering of zeros with my ar 15's. I am thinking this extra slop and the relationship here if cured could help that.

I was wondering what the group here thinks of this, here is some reading and other info to see for yourself.

this guy is the one suggesting this, alot of people are using blue loctite to deal with this issue but I am not sure its enough. if you heat and upper in the oven to 250 degrees you can get it to expand by .001



fast forward to about the 7 minute mark.

https://americangunsmith.info/2013/03/20...e-ar-15-part-1/

https://americangunsmith.info/2013/04/05...e-ar-15-part-2/

here is another link, with pictures if you scroll down of shimming the outside of the barrel extension http://forums.brianenos.com/index.php?/t...-doesnt-matter/

oh and lastly how hard would it be to change my barrel extension out to an oversized bat machine extension??
 
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I use Mega uppers and ARP barrels. They are always tight and even with Aeroshell 33MS grease on the barrel extension I still have to tap the barrel into the receiver slowly with a rubber hammer and piece of plastic against the flange.

After that I install a Mega Wedglock handguard with a titanium barrel nut torqued to 65 FT/lbs. No slop.

IMO...HIgh quality mil spec parts should not require aftermarket band aids on a new build.

In the past I found I had one upper of a brand I won't bother to mention that was not square so I used a squaring tool to rectify the problem. Since then I have only used Mega uppers with the exception of one VLTOR which I was very pleased with also.

http://pacifictoolandgauge.com/ar-tools/1139-ar-15-upper-receiver-lapping-tool.html
 
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Originally Posted By: Gman757
I use Mega uppers and ARP barrels. They are always tight and even with Aeroshell 33MS grease on the barrel extension I still have to tap the barrel into the receiver slowly with a rubber hammer and piece of plastic against the flange.

After that I install a Mega Wedglock handguard with a titanium barrel nut torqued to 65 FT/lbs. No slop.

IMO...HIgh quality mil spec parts should not require aftermarket band aids on a new build.

In the past I found I had one upper of a brand I won't bother to mention that was not square so I used a squaring tool to rectify the problem. Since then I have only used Mega uppers with the exception of one VLTOR which I was very pleased with also.

http://pacifictoolandgauge.com/ar-tools/1139-ar-15-upper-receiver-lapping-tool.html


I just bought ones of those tools but I bought it from brownells, I wonder if they are the same unit.
 
I guess I've never seen a quality barrel that needed any adjustment in barrel nut torque to get good accuracy... This seems pretty hookie to me grinding out the holes in your barrel nut.. Indexing to the next alignment hole should not make that much difference in harmonics.
 
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