[jkpq45]

Figured I'd turn some sub-gauge inserts for my 12 and 20 gauges. Everything kosher with using aluminum, or should I use steel? Would A36 (rebar) be appropriate if I figured out how to rust-protect it?

First project will be a 12 to .410 gauge or .45LC, then I'm thinking of getting fancy and doing 20 gauge to .22LR.

Thanks!
jkpq45

[Virginian]

I'd use 4140, but I have not done any analysis, that's just off the top of my head. Don't want to run into any differential expansion issues.

[oneounceload]

Look at what Briley and Kolar use for theirs

[CountryUgly]

This is kind of out of my league but I'll try. Is the A36 brittle at all or at risk of shattering under pressure? If not I don't see why it would not work. As far as rust proofing goes how about having it hard chromed.

[rcmodel]

Rebar is not steel, or at least very high grade steel. It has a lot of impurities in it and I would never use it for what you suggest.

Many sub-caliber shotgun inserts are made from aluminum.
I don't know what grade it is, but it's not the stuff from the hardware store.

rc

[T Bran]

Having welded a lot of rebar in my life I can say for certain it is a crapshoot at best. Some places on a piece of bar weld like good hot rolled steel while other places on the same bar are more akin to welding sardine cans.
For something like a chamber adapter at a minimum I'd be thinking along the lines of cold rolled steel rod.
If I was planning on making an adapter I would post a want to buy ad for a used or shot out bull barrel and turn it to fit the chamber and maybe 12''of the bore of a 20 gague single shot.
Just my thoughts, feel free to experiment just use the best components you can find.
Have fun.
T

[TurtlePhish]

I don't know if they're in your area, but Grainger has round bar stock of cold rolled 4140 for a pretty low price. I have a few feet in the shop right now for a couple cannons.