doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com welding a hole in barrels

Bill,
Since the barrel is cooler, the weld will cause hardening all by itself if enough carbon is present. When I welded these barrels, I used mild steel rod. The welds themselves were ok to file, but the area right along the edge of the weld was very hard. I'm guessing something like 60 RC or more based on the way the file wouldn't cut it well. When you harden something, it creates stresses. This is especially true when you harden something locally and there is a disparity of hardening across the part. Given that the hardness was very high in my case, and that it was only local, I would feel much better about annealing than leaving it as it was. High internal stresses and high hardness is a bad combination for a part that will see additional loading stress. If you've ever seen a weld crack right in front of your eyes as it cooled, you have seen the result of internal stresses beyond ultimate strength of the steel.

If you're worried about annealing weakening the barrels to less than their original condition, I think you can lay that to rest. Barrels are relatively soft, except for a few exceptions. All this dent removal discussion is a good indicator of that. But the first time you see an engraver start scratching one up, that's conclusive.

I would treat damascus exactly the same for a weld. Weld it, try to file it, if it has hard spots, anneal.

I agree with Chuck, if after repair you find the area around the weld to be hard to strike off, anneal it properly. Yes barrel steel is relatively soft if it were to hard, it would be very brittle. Just remember when undertaking a project such as this to use someone qualified. The brass internal chill bar will help with hardening as brass will soak up some of the heat and keep it from spreading outside of the weld zone. Filling the void between the bbls is not going to help that much unless you use something tougher that the barrel steel itself. I wouldn't recommend this as it will likely cause a violent rupture somewhere else. Ever seen a barrel fired on an ultra slow motion camera? Suprisingly enough the barrels actually expand ever so slightly and then return to original shape after pressure has tapered off. The elasticity of the steel allows this. I certainly would not want to compromise this with some kind of hard backing material. Just watch your hardness and test with a file, anneal if necessary.

I once bought a Fox Sterlingworth that had a weld about 3-4 inches from the breech. I didnt know it until, for some reason the spot changed color after some shooting..........The dealer I bought it from (local), didnt know it either and when he saw it, insisted on buying it back. He then cut the bbls in half and tossed them..."liability issues"...I thought it a terrible waste...

I have welded a hole in a set of damascus barrels for a member here. The hole was less than 1/16" diameter. It was about 6" from the breach end. I ran an argon purge through the barrels and and used used a 3/32" diameter mild steel filler rod to plug the hole. I did not use a mandrill or heat sink. Using a large diameter filler rod you basically melt the rod first with it laying right on the barrel. As the rod reaches the melting point the barrel wall is so thin that it reaches melt also and the drop of weld just falls into place. If you get off the pedal quickly. The weld only takes a few second. You could touch the barrel with a bare hand a second or two later. It left a small dimple on the inside that needed to be polished down using fine emery on a wooden dowel. The barrels had plenty of wall thickness and after honing, which was done by the owner I am sure the weld was undetectable. Polishing the OD was a 5 minute job. I don't like using a plug for this type of repair. No matter what material you use some of the plug material will purge into the weld and that is no good. You are bound to end up with a weld that is not 100% filled or with porosity in the surface or both. With the argon purge you do have a small dimple on the ID but the weld is clean and 100%. As for the barrel described the hole is deep and the clean-up will be more difficult. And the bigger the hole the bigger the dimple. Also any type of heat sink is drawing heat away from the weld. When you are trying to weld fast and not cause a lot of heat drawing the heat away can be more trouble than it is a help. And if the mandrill is tight to the barrel any purge would be useless as it would sealed off from the weld area. If it were to get stuck it could be a disaster. If someone were going to try using a plug I'd take the time to make something that is collapsible.

Bill G.
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I have a crack starting just in front of the choke about 2" from the muzzle of a damascus barrel and have heard of micro welding. Is that better than TIG on damascus or about the same? :MIKE