Now before you all go off hear me out… I’m considering putting low strength loctite on a 98 I’m building. This is not for it’s thread locking properties but rather thread sealing. I’ve had a gunsmith recommend it to me - he said if you don’t the rust bluing solution will seep into the threads and cause perpetual rust issues later on. With the threads loctited it seals them and stops the solution getting into the threads.

I’ll be using a hydrochloric based (or at least - non nitric) rust solution as it is not possible for me to get any nitric acid.

So - given this, how bad an idea is low strength loctite?

I've found it much, much easier to remove the barrel when rust bluing. For me, it's just more practical to go through all the steps of rust bluing, especially carding the receiver, to handle two separate parts. This obviates the need for a sealer.
Roger

If the rust blue solution seeps into the barrel threads you are putting way too much on!

quote:

Originally posted by RogersGunWorks:
I've found it much, much easier to remove the barrel when rust bluing. For me, it's just more practical to go through all the steps of rust bluing, especially carding the receiver, to handle two separate parts. This obviates the need for a sealer.
Roger

that’s true I’m sure, do you ever have issues marring the barrel on the vice when Screwing it back on?

quote:

Originally posted by metal:
If the rust blue solution seeps into the barrel threads you are putting way too much on!

I guess that’s right. Even a little right at the joint though?

I'd recommend applying with a cotton ball dampened with your rust bluing solution. The joint can be effectively sealed with a little brushing lacquer. Clean up the areas to be blued around it with lacquer thinner prior to bluing. After you blue it, soak in a saturated cold solution of baking soda and water to neutralize the HCL.

I am with Roger on this one. I think a bigger problem is with the oil and other junk that seeps out rather than in that causes the problem

If your rust bluing solution seeps out from the threads, you are putting way too much on. I think someone else already said that.
Yes, even at the mount; your cotton ball should be only slightly wet/damp. You are not slopping the solution on. If you do, you will get streaks. Believe me.
Not something to worry about. If you steam, as I do, there is nothing to get into the threads (like water) either. I do not remove the barrel either; don't want the blocks to mar the new blue.
But if you really wanted to seal the threads, it wouldn't hurt anything.
I just wash the blued parts in running hot water; there will be no residual solution if you use Bobster's formula.

I always do the 2 pieces separate, then remount the bbl after fininshing.
Doesn't matter if it's a handgun or a rifle.

I've never marred a bbl or frame in the re-assembly process.
I do like to use some lube on the threads when re-assembling and when both parts are finished blued..

Reassembling while in the white and using lube on the threads can lead to the lube luquifying in the boiling stage and start to run backout of the bbl/frame joint.
That'll spoil the blue job in that area as well as contaminate your bluing stuff.
Not always, but it can be a problem.

I don't like the idea of assembling a bbl/frame w/o any lube on the threads,,just me.
But if you do and you then were to rust blue it, the amt of bluing soln applied in either an Express or a Slow/Cold Rust blue method shouldn't be of any quantity that would seep into the joint and rust away for evermore.

Even if the soln did get in there and cause rust,,boiling the assembly as usual for the process you're doing will kill the red rust inside there and turn it to blu/black just like on the outside.
It won't ever get carded but it won't ever grow on you ether

I too, blue the parts separately....easier access to the chamber, crown, bore for a final cleaning and polish. I put a light coating of grease on the threads

I use aluminum blocks...must have a few dozen I made over the years for various barrel contours. Just a couple layers of adding machine tape between the blocks and the barrel..never marred a barrel..Of course, make sure there's no chips or crud on the blocks!

What does anybody do to make sure the barrel goes back on to the same headspace?

You screw it back with the same torque. It will go back where it came from. Or you put an index mark on them. Or make the sights plumb. Or gauge it again; the difference between a go and no go gauge is fairly huge.

Boiling is not usual for me; I steam the parts; using hi temp grease on the threads first insures that none will seep out at any time. I stopped boiling when Bobster taught me the steam method.
I never remove the barrel and I actually use hi temp anti seize compound on the threads. Modern stuff can be useful even on a 200 year old process.

I have both boiled and steamed, and have had oil contamination. Separate the barrel from the action and save yourself a headache.

Thanks guys, points taken about the amount I’m putting on! I guess the main question that arises is whether to blue with the barrel on or not - something which seems a matter of what works for you as opposed to a right or wrong? I can see it’ll be a nicer easier job with the barrel off, but the possibility of marring the fresh blue when putting back on. Also, how much torque should the final install be?

Kolo - headspace won’t vary as once the shoulder/inner C has been reached it remains the same. It’s just the amount of pretension in the threads that change. Getting sights to line back up is more important, but using the same torque and a witness mark sorts this out. Also, I’m installing a barrel mounted sight and receiver sight so can triple check they all line up (after having previously aligned them)

You won't have oil contamination if you don't use oil. As I said, I use hi temp anti seize for all my barrels. Never had oil contamination.
How much torque should the final install be? How much torque was it to begin with? It varies on factory rifles from almost zero (on one Ruger I had), to Kenworth lug nut torque, which is like 300 ft pounds.
I use a 4 foot bar and put a moderate amount of pressure on it; I do not measure the torque. Ain't had one fall off yet.

Is it true that rust blue is not as hard wearing as caustic blue?

No, rust blue is tougher than hot blue.

Im not a gunsmith although I have done some gunsmithing on my own rifles. I have however done a lot of mechanic work, and coming at this from a mechanics point of view using loctite as a thread sealer makes no sense at all. There are far better options for thread sealers. The amount of loctite that one would have to use to actually create a seal would be absurd. If I were going to attempt to seal barrel threads I would start with a very small amount of thinned out non hardening sealer, very discretely applied.