doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Ithaca Barrel Safety Concern

Jerry,
I believe the breaches are brazed together with the lump. Ribs are soft soldered, of course.

Another problem with welding these barrels is the weldability. Yes, anyone with a TIG can weld them, but the last time I did it on an American gun of this vintage, I kept chasing cracks. This is indicative of high carbon content in the barrel steel, beyond the .30% that is normally considered the limit of "weldability". This area is probably the single most critical area of the barrel, or gun, for that matter, and the "flaw" is of a particularly nasty orientation and size. Trusting a weld of an essentially unknown alloy for your wellbeing is more than I would gamble.

P.S. Most modern barrel steels are 4140 today. 4140 is another "non-weldable" alloy, which can be welded, but has the propensity to produce flaws in welds due to the .40% carbon content. Although I have no factual data on NID barrels, I suspect they are either 4140 or very similar.

In the L C Smith Plans & Specifications book, even quite early on, while the bbl steel was not specifically called out it was listed as having approximately 40 points carbon. At that early date it was likely something like a 1040 or perhaps a 1340 (Manganese steel). By the time the Nid came along as Chuck has said it very well may have been made of a higher alloy steel as 4140. In any case 0.40% carbon can lead to welding problems. It is a real shame someone drilled that hole so close to the chamber.

I do think Miller's idea of a 20g chamber sleeve is probably a safe solution as it adds wall to the chamber and reduces hoop stress from the smaller diameter at the same time. A sleeve from piece of 4140 or 4130, heat treated to about low 30s which would add tensile strength without overly reducing fatigue and fracture toughness, would be something to consider.

I like Chuck H idea,
fix it the right way and it'll last forever.

Chuck;
I do agree a good chamber sleeve shoud work, but I don't want to take credit un-justly. I don't recall for sure now who suggested that but it wasn't me. Is there another Miller posting?

you could have a tight fit steel rod inserted into the hole and soft soldered in place. This would fill the void and not have to worry about weldability

Sorry Miller,
It was 2holer.

Gunny,
the issue is not filling the hole, but rather the remaining effective wallthickness and its ability or lack of ability to carry the loads. A soldered plug won't add to the load carrying ability in any meaningful way.

What if you filled the hole and disabled the ejectors?

No problem at all Chuck, just didn't want to take undue credit. I can easily see where it would be easy to recall 2-piper for 2holer.