12 gauge chamber inserts...

[K-Roc]

Dina Arms

Inserts are aluminum - good for 100 rounds before they start losing accuracy (says the manufacturer)

http://store.dinaarms.com/default.asp

That doesn't seem very good...

[migrant hunter]

I haven't got to the range yet with the Dina arms .22 and .357 inserts but I did test fire it just now when I was walking the dog.
I'm very impressed with how quiet the .22 is with shorts. Perfect for grouse when elk hunting. The empty .22 shells fall right out, .357 is held in with a rubber O ring. The only malfunction was missfires from some old .22 shorts.
I forgot to mention, I have a couple of .410 inserts from another site sponsor. I find them very useful.

[Canada Ammo]

12GA actions and especially aluminum 12GA actions (Turkish shotguns) are not rated for the pressures of any rifle rounds, not even 7.62x39 and 223.

Pistol calibres are possible but with the cost of quality steel, machining chambers and actually rifling them, we would be no cheaper than any other vendor.

We may look into 20GA and .410 adapters.