Lots of loctite and a barrel that over timed (mini rant)

[CanuckR]

So last night I pulled the barrel off of a buddies new to him rifle to thread it for a muzzle brake. It is a very nice rifle, Surgeon action, match barrel, it was built buy a reputable smith. So here is the funny part. First off the barrel was on there very very tightly, finally got it to break lose and there is a ton of green loctite in the threads. Think to myself, "meh whatever not the first barrel I've seen loctited on." Clean it up, thread muzzle, install one of the GST precision brakes on it. (Nice brake, especially for the money) Before I took the barrel off I marked TDC on the barrel and the action with a sharpie so I could tighten the barrel back up to where it was and time the brake easily.
So I get the brake on, clean up the loctite and apply a bit of anti seize to the threads instead. Slap the wrench on the barrel and go to tighten it up, the weight of the wrench alone turns the barrel up to the timing mark, maybe even a bit past it. Give it a bit more to torque the barrel up and now the timing mark is at the 1' O clock position or a bit more in relation to where it was when I took the barrel off.
"Well that sucks" now I need to re time the brake, I decided to trim the brake to get it timed up again instead of lengthening the thread tenon on the muzzle.

I did not stick a go gauge in the chamber as I don't own one for 308 at the moment, I took the firing pin out an ensured it would swallow a few types of factory ammo I had here. By far not a perfect set up but it chambers fine and shot great today.

So I have been trying to figure out what happened and why it happened. My thoughts are that the original builder made a bit of a mistake in a dimension somewhere and instead of tightening the barrel all the way up they just slapped a ton of loctite on it, and turned it up hand tight and left it.

Orrrrrr, hopefully what happened is a bit more of an "honest" mistake and all the loctite that was put in there started to harden up a bit quickly and caused a bit of false torque up?

I highly doubt the anti seize created enough lube to let it over time that far on it's own.

Any thoughts or ideas?

 

[guntech]

Never seize will cause it to torque tighter over dry threads...

I don't understand why it would be installed as 'loose' as you describe if originally the barrel required no indexing (no flutes)... if when torqued tight and the head space was tight the smith would only have to run the reamer in 2 or 3 thou and he could do that by hand...

Your top dead center mark with a sharpie could be off slightly too...

I much prefer to index brakes when the barrel in on the action, using a level on the action and on the brake...

 

[CanuckR]

Yeah I understand the anti seize will tighten up a bit more. I've done a few other barrels using a sharpie to make a timing mark from the action to the barrel, just to make sure the barrel goes back one exactly the way it was. ,which is what I did here. The line went onto the action to set up as a reference for reinstalling the barrel. I've done a few barrels this way and all of them except this one have torqued back up to the timing mark I put prior, even with some anti seize on the the threads.
I use the sharpie mark as a baseline while the barrel is in the lathe, once the barrel is back on the action I level the action and set the brake to TDC.

 

[SND]

Guessing the thread was on the loose side a bit, green loctite( like 609, 620) is normally used to take up a gap when the fit is loose(bearing/bushing). Maybe that was just enough to make a slight difference when torqued without the loctite in there.
Ah well, sh* t happens, then usually someone else fixes it...