Gunsmithing Seized Barrel Threads: The Fix

[Rubicon Precision]

Inspired by the "What Were They Thinking" thread.

This is Robert. Don’t be like Robert...

This is a personal project so at least I’m not buying a customer a barrel. This barrel is 1.375 for 5” then tapering to 1.010” at 32” and I have a second one. Losing 1-1/4” on the chamber end isn’t really going to be the end of the world for me.

So, the threads were not too tight and the barrel had already been screwed on/off hand tight several times during the machining process. I knew it was going to be a while before I could finish this project so I washed the barrel and receiver with hot water and Dawn and dried. A little while later I was sitting in my office (probably after a few cocktails) looking at the barrel, receiver, bottom metal and stock. I figured I’d screw the barrel on by hand and toss it in the stock to see what it will look like. Well, the dry barrel screwed in just fine....until it didn’t. I heard squeak, and it got tight. Tried backing it off and it only went about 1/4 turn. I immediately soaked it with penetrating oil and tried to back it off again. No joy. I knew at this point the receiver would be destroyed if I tried to use tools to unscrew it. It was time to sacrifice a bit of barrel and hope the receiver is OK.

After the tenon was extracted, the receiver looked pretty good. Just one tiny nick on a thread. I ended up making a mock tenon from some 4130 bar I had and lapped the threads with some 800g alox lapping compound and now can't hardly tell anything happened.

Moral of the story, ALWAYS lube your threads!

Started with this.

Knowing the the receiver would be destroyed if I tried to use force to unthread it, I cut the barrel off with a band saw. I then made some t-nuts to fit the front of the knee mill. I don't think this slot is really meant for machining off of, but for this OP, it wasn't going to be an issue.

Getting it as vertical as I can, hoping the threads are pretty parallel to the outside features of the action.

I knew this Chinese boring head and mystery boring bars would come in handy some day...








Just the smallest spot of galling on the threads. This would have been much worse if I had used tools to try to remove the barrel.

Good as new, just a bit shorter.

 

[ShtrRdy]

Oh man! Good thing you're talented. Thanks for sharing your lesson.

-- Todd

 

[DAVETOOLEY]

Been there done that two times.

 

[LRI]

2 types of gunplumbers:

Those who have stuck a barrel
Those who will

 

[XLR308]

Looks like you have made the world's most expensive heli-coil.
Glad it worked out ?

 

[mcfred]

I like the Mill setup. Had I been presented with that same issue I'd've probably spent a long time effin' around with the lathe to accomplish the same thing. Thanks for the reminder about lube.

 

[EXTREMEPREJUDICE]

Nice problem solving, props on admitting things go wrong...................................most wouldn't.

 

[Rubicon Precision]

2 types of gunplumbers:

Those who have stuck a barrel
Those who will

Yep.

 

[Rubicon Precision]

Nice problem solving, props on admitting things go wrong...................................most wouldn't.

No matter how right you do things, sometimes they go wrong. No matter what happens, making the wrongs right in the customer’s eyes is extremely important.

 

[mcc308]

So what lube are you guy's using on the threads?
Btw thanks for sharing.

 

[gnochi]

I’ll be the first to admit that my engineering degree doesn’t outweigh my relative lack of gunsmithing experience, but nickel-based anti-seize is my substance of choice.

It holds up to the heat, doesn’t catalyze cracking in stainless steels (like copper), gives you reasonable lubrication on barrel/bolt/whatnot installation and removal, essentially doesn’t corrode in any environment the gun itself will survive, doesn’t itself cause corrosion if you damage the oxide layer on aluminum (like graphite), is galvanically compatible with just about every steel alloy out there stainless or otherwise, and isn’t horrifically more expensive than the other options.

 

[Ruggedtouch]

Here’s a question in the hope of learning. Should I remove the barrel from my factory AX, lubricate the threads and screw back in to the receiver?

 

[gnochi]

Here’s a question in the hope of learning. Should I remove the barrel from my factory AX, lubricate the threads and screw back in to the receiver?

I would be astounded if they hadn’t put anti-seize (henceforth goop) of some kind on it in the factory. If it’s shooting well, and you don’t otherwise need to pull the barrel for some reason, I wouldn’t bother messing with it. If you do need to pull the barrel for some other reason, go ahead and goop it before you reinstall.

 

[Ruggedtouch]

I would be astounded if they hadn’t put anti-seize (henceforth goop) of some kind on it in the factory. If it’s shooting well, and you don’t otherwise need to pull the barrel for some reason, I wouldn’t bother messing with it. If you do need to pull the barrel for some other reason, go ahead and goop it before you reinstall.

Thanks for the assist. I think I’ll go that route and when I swap barrels, I’ll get to the hardware store and find some nickel-based lube.

 

[DAVETOOLEY]

Thanks for the assist. I think I’ll go that route and when I swap barrels, I’ll get to the hardware store and find some nickel-based lube.

AI's actions are Melanited meaning for lack of a better term, they aren't bare metal and sticky like others. I would just use synthetic grease and call it good. I've never heard of one seizing up.