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Posted: 6/15/2018 3:37:39 PM EDT
What is the exact process of doing this?  Do you coat the extension in Loctite and insert it into the upper, or is there some overly complex method?
Link Posted: 6/15/2018 3:49:29 PM EDT
[#1]
Yep that's it. Loctite can only do so much though so use shim stock as well to reduce the clearance if there's more than .002". Be sure to use red or green loctite. I clean the bore of the receiver and barrel extension with acetone and once dry coat both in loctite. I wipe dope what oozes out between the receiver face and extension shoulder and wipe off excess on the threads. I apply a little bit off oil to the threads to neutralize any left on it since there will be some and more will ooze out when you tighten it. I then tighten the nut using a reaction rod type holder and then I'll clean up some of the excess that runs out into the action with q-tips and let the barrel sit muzzle down with no stress on the action for 24hr to cure.
Link Posted: 6/16/2018 9:12:12 AM EDT
[#2]
Agree with all that was said but a better choice than Loctite is Permatex Sleeve Sealer. Loctite also makes a Sleeve Sealer but it can be a little thinner and harder to find. Both are green in color. As I'm sliding the extension into the receiver I wipe off the excess as it pushes out. if you have lapped the receiver, make sure you check the ramps by pre-fitting it and shim between the receiver and the extension. You'll need to cut a notch out of the shim to clear the alignment pin. You pre-fit just as if you were final torqueing the barrel nut. Get extra shims in case you damage them in the pre-fit process. If you need to, you can also shim between the barrel nut and the extension. This will help with barrel nut alignment and keep you from over torqueing it.

Some will argue that it's not necessary to do all this but if you're building a precision rifle then this process should be done.
Link Posted: 6/16/2018 2:24:04 PM EDT
[#3]
I use 620 but thats up to you.  Made for cylindrical gaps and larger gaps than standard loctite.  Takes a torch to remove though so no coated stuff or fiber.  Acetone or alcohol on extension and inside receiver, dry, small amount inside the receiver, lightly coat the extension, insert ,clean any excess, torque barrel nut down.  Check inside receiver for any oozing, clean that with qtip.  Let it set straight up for 48 hrs.  Done.
Link Posted: 6/17/2018 1:41:31 PM EDT
[#4]
out of curiousity has anyone done a before/after testing on this? i'd like to know how much it helps.
Link Posted: 6/17/2018 2:50:43 PM EDT
[#5]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By garred8787:
out of curiousity has anyone done a before/after testing on this? i'd like to know how much it helps.
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I'd be interested as well.
LocTite was designed for preventing threaded components from loosening, therefore, I'm skeptical that a glue can withstand the torque and pressure to be a good bedding material.
Link Posted: 6/17/2018 3:12:34 PM EDT
[#6]
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Originally Posted By Renn:

I'd be interested as well.
LocTite was designed for preventing threaded components from loosening, therefore, I'm skeptical that a glue can withstand the torque and pressure to be a good bedding material.
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Loctite 620 is a bearing surface bedding material.
Link Posted: 6/18/2018 12:09:47 AM EDT
[#7]
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Originally Posted By robpiat:

Loctite 620 is a bearing surface bedding material.
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Learn something new.
I'll give that a try next rebarrel
Link Posted: 6/19/2018 12:51:32 AM EDT
[#8]
Originally Posted By garred8787:
out of curiousity has anyone done a before/after testing on this? i'd like to know how much it helps.
View Quote
Originally Posted By Renn:
I'd be interested as well.
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It probably wouldn’t accomplish much by itself.  It’s one piece to a larger/more complex puzzle.
Bed an upgraded barrel in conjunction with an upgraded trigger, bedded action, optimized/consistent action screw torque, quality ammunition, quality optic (including base/rings), etc... and you get measurable results
Link Posted: 6/21/2018 1:28:25 PM EDT
[#9]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By garred8787:
out of curiousity has anyone done a before/after testing on this? i'd like to know how much it helps.
View Quote
Accuracy is incremental.
Link Posted: 6/24/2018 9:01:41 AM EDT
[Last Edit: bfoosh06] [#10]
Link Posted: 6/25/2018 10:48:23 PM EDT
[#11]
thanks bfoosh06 I may give it a try on my next recce build.
Link Posted: 6/25/2018 11:56:10 PM EDT
[#12]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bfoosh06:
@garred8787 .... @SirSqueeboo .... @Renn
I did some with my PSA PA10 Gen II in 6.5CM... in my rifle it helped quite a bit. My test wasn't a beat all , scientific test, but I felt like I had nothing to lose.

So I tried it.

I am not a gunsmith.. just an average guy, so everything was done with easy to purchase and use tools.

Criterion has a video concerning "How To" this... and that was my guide. ( Part 3 )

http://criterionbarrels.com/accurizing-the-ar-15-video-series

Please read the whole thread for the results... it is some of my first results lapping a receiver face and Loctiting in a barrel.  Enough factory ammo's responded very well, but not all.. but enough to make me believe in the process.

Again while the thread is a little cattywampus... the actual results now make me "True and Glue" all my long range rifles. YMMV...

https://www.ar15.com/forums/industry/PSA-PA10-GenII-lower-w-PA-65-review-START-at-the-beginning-again-UPDATED-with-Tn-G-results-/301-285762/

Some of the improved group differences... The measured group size of both before and after....

I DID NOT subtract the bullet diameter from those measurements ... so subtract .264", 5rd groups ...Limited ammo for testing ( One of the reasons it isn't a beat all test )

Difference in group size, FGMM 130gr Hybrid OTM..... Before 2.3660" 5rds, .... After .9580".

Difference in group size, .Hornady 140gr ELD Match.... Before 2.2045" 5rds, .... After .9290".

Difference in group size, PRIME 130gr HPBT Match.... Before 1.9165" 5rds, .... After .9620"...

Difference in group size, Federal Fusion 140gr..... Before 2.1445"... After... 1.4355"

Difference in group size, Hornady American Gunner 140gr BTHP.... Before ...1.1950" .... After.... .7520"

Difference in group size...Creedmoor Sports 140gr Nosler BTHP... Before 1.5135"... After... .8770"
.

And BTW... I will do this TnG today on another "before and after" upper... so I do believe in it.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bfoosh06:
Originally Posted By garred8787:
out of curiousity has anyone done a before/after testing on this? i'd like to know how much it helps.
@garred8787 .... @SirSqueeboo .... @Renn
I did some with my PSA PA10 Gen II in 6.5CM... in my rifle it helped quite a bit. My test wasn't a beat all , scientific test, but I felt like I had nothing to lose.

So I tried it.

I am not a gunsmith.. just an average guy, so everything was done with easy to purchase and use tools.

Criterion has a video concerning "How To" this... and that was my guide. ( Part 3 )

http://criterionbarrels.com/accurizing-the-ar-15-video-series

Please read the whole thread for the results... it is some of my first results lapping a receiver face and Loctiting in a barrel.  Enough factory ammo's responded very well, but not all.. but enough to make me believe in the process.

Again while the thread is a little cattywampus... the actual results now make me "True and Glue" all my long range rifles. YMMV...

https://www.ar15.com/forums/industry/PSA-PA10-GenII-lower-w-PA-65-review-START-at-the-beginning-again-UPDATED-with-Tn-G-results-/301-285762/

Some of the improved group differences... The measured group size of both before and after....

I DID NOT subtract the bullet diameter from those measurements ... so subtract .264", 5rd groups ...Limited ammo for testing ( One of the reasons it isn't a beat all test )

Difference in group size, FGMM 130gr Hybrid OTM..... Before 2.3660" 5rds, .... After .9580".

Difference in group size, .Hornady 140gr ELD Match.... Before 2.2045" 5rds, .... After .9290".

Difference in group size, PRIME 130gr HPBT Match.... Before 1.9165" 5rds, .... After .9620"...

Difference in group size, Federal Fusion 140gr..... Before 2.1445"... After... 1.4355"

Difference in group size, Hornady American Gunner 140gr BTHP.... Before ...1.1950" .... After.... .7520"

Difference in group size...Creedmoor Sports 140gr Nosler BTHP... Before 1.5135"... After... .8770"
.

And BTW... I will do this TnG today on another "before and after" upper... so I do believe in it.
Thank you so much for that hard work!
Link Posted: 6/26/2018 3:54:13 AM EDT
[#13]
Link Posted: 6/28/2018 10:32:59 PM EDT
[#14]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By garred8787:
out of curiousity has anyone done a before/after testing on this? i'd like to know how much it helps.
View Quote
Yes I have, on several guns, including AR15s and AR10s.

The .308 Krieger barrel test was interesting.

Would shoot maybe 1.5" on a good day, 5rd group at 100yds.

After I completely worked over the build, bedded the barrel into the upper, and a bunch of other things, it was shooting .6" - .75" 5rd groups with a random 155gr SMK load.

On an AR15 with a JP Super Match .223 Wylde barrel with heat radiators, same thing.  1.7" at 100yds.

Trued the receiver face, bedded it, freaking bug-holer.  Friend who I built it for let his daughter shoot it.  She was shooting 1/4" groups out of the gate at 100yds with 55gr Federal fodder.

I bed all my builds now, true receiver faces, and match uppers to extensions.  If the extension is loose in the upper, I find another upper or build up Cerakote in that portion of the tunnel (not the full raceway-I leave those alone on Mil-Spec uppers with baked on dry film lube), then create an interference fit, along with Blue Loc-tite.

Hi-Power smiths have been doing this once they saw the Army Marksmanship Unit armorers start to do it.

It's one of many things you can do for accuracy.

This is all under the premise of starting with a good barrel.

Don't expect miracles with a bargain barrel that walks with heating or anything like that.
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