Lapping receiver and bedding barrel extension

varminter .223

Active member
I tore my 22 Nosler apart. The willy nilly shot to shot accuracy changes were more than I could take. Should have done it to start with but since I need a new handguard to mount the radius I decided to lap the receiver and bed the barrel extension. I am not sure how much it will help but it sure can't hurt. I think having a barrel nut that I can actually torque may help as well. Im curious if anyone has seen accuracy improve by doing this? Most accurracy sticklers probably wouldn't assemble one without doing it in the first place to even have a comparison.
 
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Originally Posted By: varminter .223I tore my 22 Nosler apart. The willy nilly shot to shot accuracy changes were more than I could take. Should have done it to start with but since I need a new handguard to mount the radius I decided to lap the receiver and bed the barrel extension. I am not sure how much it will help but it sure can't hurt. I think having a barrel nut that I can actually torque may help as well. Im curious if anyone has seen accuracy improve by doing this? Most accuracy sticklers probably wouldn't assemble one without doing it in the first place to even have a comparison.

Yes it helps in many cases. Squaring the receiver is important for decreases lug stress. This results in less breakage and better treatment of your brass. More consistent shot to shot IMHO. Every upper that I have had built by Ritch, over three dozen, have been squared with a cutter.

Since this came up an observation over the years. Many fellows believe because they just spent a good lottery winning on a big name billet upper that they are perfect and don't need squaring. Experience shows many will benefit from it much to the chagrin of the proud owners. It's all in the machining. Billet means squat if the company doesn't pay attention. I have a story or two about out of spec billets that were embarrassing to the manufacturer but if a man makes it a man can sure screw it up.

Bedding is needed if you have a loose barrel/extension interface. Many do not require it if they are tight to start.If you can wrap a Siamese around the barrel and slide it in it would be beneficial. It's not that the parts are bad but it may well be the tolerance stacking small/large combination. Those set ups that make you freeze the barrel and boil the upper don't need bedding. Very few of mine have been bedded. Probably less than five.

It's nuances that make these guns better. Kitchen tables and a crescent wrench work but maybe not so good if you are on THE QUEST.

Greg

Bolt height/clearance just assures there is less room for slop and consistent location of the bolt when the cartridge is in place. Think of it as a round hole 0.5 inches deep. Now slide a part that is on a shaft in the hole. The part is 0.45 inches tall so you have 0.05 slop. Now slide a similar part that is 0.40 inches tall. You have 0.10 slop. The shaft will move back and forth slightly so in effect your head space can vary a tad.

You can shop around and swap bolts but little you can do other than that. The barrel extension manufacturing sets how much room you have and then the bolt maker does his part. This is a minutia issue, IMHO, and is probably smoke and mirrors at the level we shoot. I've never heard of the AMU doing it but then I don't hear everything. I also have never had it mentioned when I was talking to big name builders on the process and I have talked to a few of those..lol


 
The first one I had squared was at the suggestion of Mike Milli after posting on here of inconsistency. Groups tightened noticeably and I've done it to each one since. Bedding is something he said he does also and may not help always but will never hurt. So I went with it.

A local machinist/smith claims the bolt clearance issue is important for top shelf accuracy and he sets the barrel extension to match a specific bolt if possible. He's chambered some of my most accurate barrels so I have no reason to doubt it helps.
 
GREEN VIBRA-TITE.
For mating barrel extensions to the receiver, Green Vibra-tite, I got mine off Ebay, is the best I've used. It's for slip on non-threaded parts. If let set up a day or two, it creates a great seal filling in all gaps & will come off will very little work. Mid-West Gun Works sends red Vibra-tite to use on their gas block screws & Odin Gun Works also endorses it. I had rubber handgrips coming off of a walker handle bars, used green Vibra-tite & that was the end of that.

Jim D
 
Vibra tite 54110 looks like exactly the thing needed. I ebayed a bottle but won't have it in time for this job. I am gonna use Permatex blue as I am like a child and can't wait lol.
 
Well, I got it all back together with the Matrix Foxtrot. I am very please with this handguard and I am glad I didn't opt for a more expensive one. I can't see needing anything more rigid.
A word of advise......only put the loctite on the barrel extension. I put it in the receiver first and it all ended up being pushed out and in to the lug area. A little break clean blew it out but it concerned me for a moment.
Oh I forgot to mention, I lapped the receiver face with a wheeler engineering lapping tool and it only took maybe 40 seconds lappings by hand with light pressure and it was perfect. I used the included lapping compound. I am guessing it gain me nothing but I feel better now.
 
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