So inherent in welding an action, is straightening one. I feel I did fairly well so far, the action is straight in the vertical plane and less than 30 thousandths of an inch bowed to the right.

After rough cleanup of the welds to be sure I have filled enough metal in, I will leave the copper alignment rod in place, and heat treat the whole action-hopefully having the copper alignment rod in will help with warpage.

Smiths and those who have successfully shortened an action, what method did you use to straighten the bow or warp that happens when welding? Cold bending? Hammer and punch? Heat-shrinking the long side?

Wolf- I doubt that the Copper rod will be of much use in the straightening process, as Copper is relatively soft and is not particularly strong.


Never done this sort of thing, but I'd take a notch out of the left side, lay a bead and let the shrinkage pull the warp out.


I'd lay odds that Tom (dpcd) has better advice.

Thanks for the vote of confidence, no matter how misguided it might be!
I'd probably start with a 3 pound BFH and work up from there; my 9 pounder should be enough to solve the issue. (That is what John Henry used.)
Actually, to prevent warpage I carefully TIG weld each side, alternately from side to side, checking straightness along the process, and that will avoid bending. Doing it all at once is the hard way, in the long run.
He is right; the copper rod won't help. I use drill rod or some O1 tool rod in receivers while welding.

Depending on the process used-

The short arc process will pull upon cooling.

The preferred process will push upon cooling.

As mentioned,a copper or brass rod is comparable to a wet noodle for rigidity compared to a steel rod.

I TIG welded the pieces back just as you described, but I used the copper rod as a backer bar to prevent burn through. The alignment was mostly handled by the jig it is bolted into.

BFH it is, maybe with a little torchwork to shrink up the long side.

That was a joke; do not hammer on it.

Draw/anneal the piece first & check alignment again after relieving any stress'

The BFH is going to induce stress elsewhere.

Oil can effect.

Yes, the BFH was a joke-I was in on it

The easy way to use the BFH is with a punch and a close fitting backer block. Same way we straighten crankshafts.

I've got it straightned up within 0.010", so it's half as bad as it was. Another shot with the torch on the long side and it should pull that last 0.010" and I'll see how it looks.

If your alignment rod/heat sink had full length lugs,alignment would be improved.

For the Mosin action, I made sure my welding work was finished and would clean up, and then shrank the long side with the torch and a wet rag. The bolt now slides freely front to back, with no binding.

We'll see how stable it is after annealing, when it's dead soft I'll check again and see if it's moved or relaxed anywhere-if the bolt is still nice and free, and the front ring hasn't twisted in relation to the rear, I'll proceed with the normalization and heat treatment.