Bedding AR10 barrel

[DangerRanger]

Any smiths messed with bedding barrels in AR rifles?

I’m having CLE contour and chamber a rock creek blank and would like to do this as well as possible if I’m gonna dump money into it. On small frame ARs I’ve always just put the barre in and torqued the nut as needed for timing the gas tube, but have often read about people using loctite or marine Tex around the barrel extension to reduce vibration with the upper. However lots of people say it works great but they’ve only done one or two barrels and it very likely could have worked great without it.

anybody here have experience doing this or lots of experience building highly accurate large frame ARs?

 

[spitfire_er]

I have not bedded any, but have shimmed them. I think getting a tight fitting BAT extension is the best option for fitting a barrel to an upper, but bedding would be second best and shimming third. I shimmed my last 15 build and it worked extremely well. Next barrel I spin will have a BAT extension on it.

 

[DangerRanger]

Thanks! Hmm idk what extension cle uses. They said they would install for 75$ but it seems like they are just gonna torque the nut and I can do that for free

 

[Twdmar]

If you have a tight fitting upper to barrel extension fit, there is no need for anything. Most people use green loctite. Unfortunately most ar10s dont seem that well thought out in this area, I have 2.
On my last one I put the green loctite in. It won't hurt anything but you may need a torch to change barrels. For the average person, I doubt they would know the difference on paper. I believe it was joe Carlos who started this but he also swore by having the right barrel extension and said it about the same.

 

[DangerRanger]

Cool, so what I’m hearing is—if it’s tight let it ride and if it’s not green loctite it

 

[Twdmar]

that's correct

 

[10XSHOOTER]

I would use High Temp Red

 

[DangerRanger]

I would use High Temp Red

What makes that your preference? Honestly I’ve used very little loctite in my day, seems like red is stronger than green?

 

[Twdmar]

What makes that your preference? Honestly I’ve used very little loctite in my day, seems like red is stronger than green?

Red is a thread locker and not what you want, the green is a sleeve retainer and is meant to fill gaps. There are various green loctite products for different gaps but 620 is the norm for the AR.

 

[DangerRanger]

Sounds good, maybe it won’t even come up and I’ll just barely get it in with a little thermal fit anyway.

any other secret sauce I should look into for accurizing the large frame AR platform? Further, what’s a lofty but reasonable accuracy threshold to strive for in one of these machines. To be honest I’ve never sought to do any better than a solid and consistent moa group from any semi auto. I’m hoping with this barrel this rifle will exceed that.

 

[mac86951]

I'm sure 638 has been used. I'm not a fan of removing the barrel after its use though.

Edit. Spelling / autocorrect correction

 

[Twdmar]

Sounds good, maybe it won’t even come up and I’ll just barely get it in with a little thermal fit anyway.

any other secret sauce I should look into for accurizing the large frame AR platform? Further, what’s a lofty but reasonable accuracy threshold to strive for in one of these machines. To be honest I’ve never sought to do any better than a solid and consistent moa group from any semi auto. I’m hoping with this barrel this rifle will exceed that.

if the bolt is properly headspaced to the barrel and the barrel is free floated, it should not be hard to get sub moa. Frank does nice work and your rifle with good ammunition should shoot just fine. With 223 ar rifles, there are loads that work in just about every rifle. You dont say what caliber youre making, but if its 308 or 6.5, there is plenty of info out there too. Look up the common loads and you'll find something that shoots well no problem.
With ar15s, the barrel can be tapped with a dowel, with loctite, but inserting the dowel against the barrel extension face. I cant imagine its a whole lot different with an ar10

 

[DangerRanger]

if the bolt is properly headspaced to the barrel and the barrel is free floated, it should not be hard to get sub moa. Frank does nice work and your rifle with good ammunition should shoot just fine. With 223 ar rifles, there are loads that work in just about every rifle. You dont say what caliber youre making, but if its 308 or 6.5, there is plenty of info out there too. Look up the common loads and you'll find something that shoots well no problem.
With ar15s, the barrel can be tapped with a dowel, with loctite, but inserting the dowel against the barrel extension face. I cant imagine its a whole lot different with an ar10

Thanks, will be 6.5 creed since Im already set up to load for that for a bolt action. I will be sending him my bolt for head spacing

 

[Twdmar]

or there is this

 

[DangerRanger]

Cool vid, been reading this by Joe Carlos where he recommends doing both shimming and loctite 620

The relationship of barrel extension diameter to accuracy in the AR-15, part 1: slop in fitting the barrel extension to the upper receiver can rob your rifle of its potential accuracy. - Free Online Library

Free Online Library: The relationship of barrel extension diameter to accuracy in the AR-15, part 1: slop in fitting the barrel extension to the upper receiver can rob your rifle of its potential accuracy.(WORKBENCH) by "American Gunsmith"; Sports, sporting goods and toys industry Sport...

www.thefreelibrary.com

 

[tobnpr]

Wow...what a coinkidink

Was having a problem with a single flier after putting 3 or 4 into a cloverleaf on a new 6.5 Gredel build just last week.

Used high-temp retaining compound and it solved the problem. Similar to red loctite, but better suited for gap-filling in this application. Made a believer out of me. Criterion has an installation video online which recommends using it.

 

[LVLAaron]

Let's all do each other a favor and refer to loctite by it's number and not it's color. There are multiple products in each color.


There are two things I do to every upper I put together. I've tested these methods with 6 different uppers/barrels and see consistent improvements with each one.

1) Lap the upper with a PT&G tool (http://pacifictoolandgauge.com/ar-tools/1139-ar-15-upper-receiver-lapping-tool.html) with brownells lapping compound. This gives a minor accuracy improvement. For a 30 dollar investment, it's well worth it.

2) I bed each barrel with Loctite 609. Make sure to get healthy coverage on your extension and install it. Clean up any excess.

I see a 3/8 to 1/2 MOA improvement across any kind of load/ammo.

For a small investment you can turn an AR15 into a competitive firearm.

Here are some 5 shot groups from my latest build:

 

[DangerRanger]

Let's all do each other a favor and refer to loctite by it's number and not it's color. There are multiple products in each color.


There are two things I do to every upper I put together. I've tested these methods with 6 different uppers/barrels and see consistent improvements with each one.

1) Lap the upper with a PT&G tool (http://pacifictoolandgauge.com/ar-tools/1139-ar-15-upper-receiver-lapping-tool.html) with brownells lapping compound. This gives a minor accuracy improvement. For a 30 dollar investment, it's well worth it.

2) I bed each barrel with Loctite 609. Make sure to get healthy coverage on your extension and install it. Clean up any excess.

I see a 3/8 to 1/2 MOA improvement across any kind of load/ammo.

For a small investment you can turn an AR15 into a competitive firearm.

Here are some 5 shot groups from my latest build:

Why 609 vs 620? Easier to replace barrel maybe? I will look into the lapping tool.

 

[LVLAaron]

Why 609 vs 620? Easier to replace barrel maybe? I will look into the lapping tool.

I have and have used both. 609 is higher temp and is a little thicker out of the bottle. Just personal preference. If I were out of one and only had the other, I wouldn't be the least bit worried about it.

 

[Dave in WI]

@LVLAaron How hard is it to remove a barrel after using 609 or 620? Do you need to apply heat?