Im about to do a new precision build and people have been talking about 620 as a more appropriate bedding medium for the barrel extension than blue. I've done it in blue and red and with a little heat and a wooden dowel rod the barrel can be removed....

Is servicing a receiver/barrel removal with 620 any more difficult?..its a lot thicker and easier to work with.....

Being that I already had several rifles I bedded with 620 I too wondered regarding the difficulty to remove.  So I ordered an Anderson upper and used an old post ban fake fh rock river barrel.  Anderson upper was actually extremely tight and required thermal fitting but I bed it regardless.  Torqued to 40 ft lbs and let set for two day.  Using a jp vice block I first tried the heat gun.  Barrel temp only got shy of 300f.  620 takes 450 to break down.  Would not budge.  Broke out the propane torch and heated it up until you could see the 620 smoking.  Using a dowl and hammer the barrel came right out.  Barrel isn't going anywhere without using a torch.

I use 620 but have no intention of taking the uppers apart.

I even used Devcon Steel Epoxy on a 7.62x39mm build that had slop in the barrel extension to receiver fit. It shoots lights out.

Millions of rifles have been built without using anything and they shoot just fine. It takes a long time to burn through a barrel if you don't abuse it and keep them cleaned and lubed.

Stay away from steel cased ammo and magazine dumps and you'll be fine.

Several folks had asked about so I thought I would try it.

I considered using 620 on a build, but I found that blue doesn't move.

I removed an spr barrel bedded with blue loctite using a propane torch.  It was just as uniform as the day I assembled the upper.  I expected to find that the top of the extension had no loctite and that it had migrated into the receiver (due to heat).

I found nothing to suggest that it shifted.  Not a scientific test, but I didn't see any reason to switch.


I can see it maybe being an issue on a barrel that sees abuse or long strings of fire/mag dumps.  Truth is, I wouldn't bother bedding a rifle built for that purpose.

I use blue on all my receivers. Every single time I have taken a barrel out after the fact, not only would it not come out, I needed a heat gun to break it loose. The way I see it is if blue holds it, why go unnecessarily stronger?

Oh and I have done rapid fire in one of the hottest climates in the country:)