Reinstalling a shotgun barrel into reciever

[Gufnstuf]

Working on an old H&R bolt action 12ga and switching out a damaged barrel. Struggling to thread them back together. The receiver does not have a very solid recoil lug. It is dovetailed and has a big opening in the center for the rounds that go in the magazine. I destroyed one getting them apart. The barrel has a lug that hold the fore grip but it is very small and weak.

Most of the Barrel wrenches seem to have an engagement point for some feature on the receiver.

Has anyone had any success with a strap wrench if I put the barrel in a barrel vice?


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[PRasko]

So my understanding is that they have same thread pattern but you can't get it to seat all the way? Pictures help also.

 

[Gufnstuf]

Yes my understanding is they are 1.100-20.

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[PRasko]

So if the threads are undamaged and the same spec. You're worried about twisting the receiver etc.

-edit- hit reply button too soon

You could try freezing the barrel to see if it gives you enough clearance so you don't have to wrench so hard.

 

[Gufnstuf]

So I did freeze the barrel and heat the reciever slightly and I did get it much farther. And unfortunately there in a thread in there that is a little damaged from the original barrel being stuck. I have filed it pretty well to fix it, but that’s where it stopped this time.


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[Creedmoor]

So I did freeze the barrel and heat the reciever slightly and I did get it much farther. And unfortunately there in a thread in there that is a little damaged from the original barrel being stuck. I have filed it pretty well to fix it, but that’s where it stopped this time.


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I would go and buy the correct thread file and chase both male and female threads.

 

[PRasko]

That

 

[Gufnstuf]

Having difficulty finding a internal thread file to fit that.


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[Gufnstuf]

I figured it out. I froze it all day and hit it quick with the torch and got it loose again so I could check all the thread dimensions again to make sure they matched up.

I think there was just a little difference in the quality of the threads between the two rifles. These were made in the 40s so there may have been a little thread quality.

I was able to start the barrel in the receiver and thread it in until it got stiff and then back it up and back in until I made it a little further in. Kept repeating that process until I’ve got it all the way in and by hand it stops about 1/8 of a turn from the marks on the bottom from lining up.

Backed it all the way out and wiped quite a bit of black crud off the leading edge of the barrel threads.

I bought this to clean out the threads but now I see it would not get down called in the valley of the threads in the receiver.

Is 1/8 of a turn too much to get with the barrel against the reciever? Do I need to file to get it closer? Keep in mind 20 TPI.


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[JAL]

You may be dealing with different thread profiles, especially given the age. U.S. threads (now called SAE) weren't well standardized for the longest time. WWII forced the issue with National Coarse, National Fine, National Extra Fine, and standardized thread shape profiles.

Most threads have fillets in the grooves to help strengthen them. The amount of fillet can cause binding if there's more fillet than the peak of the mating threads have rounding on them. That said the Crudmium is likely the bigger issue.

 

[SSE]

I am sure you checked for a pin. I missed a pin one one time, got the barrel out and new one almost back on like you and could not figure it out for the longest time. Just enough pin left to keep it from threading all the way back on.

 

[gassprint1]

Been reading this. I bet, back in the day those receivers were heated hot when the barrel was put in to make a tighter fit and faster worker install. You have to be really careful freezing 1 part and heating another. I tried that once and cracked the thinner heated mild steel. I was replacing a bearing in a hub