I use to have an adaptor. I shot it one time back some where around 2002. I have no idea where it is now. I may have thrown it away. But maybe not.

For a long time the fellows making these thing were making them to CIP standards. Quite often they would get stuck. I have extracted a few-is 4 a few? I have not heard of one being stuck in recent times. I think the makers have adjusted the measurements so the adapters don't hang up.

Lee adjusted their measurements so their sizing dies reduced the brass to fit 99% of all Martini Chambers.

Of course we know the Martini Chamber was made just before the age of cartridge standardization for a foil case. The only part of the chamber that was more or less standard was the area of the chamber supporting the steel case head. Forward of that the chambers were a bit arbitrary. The shoulder was an ogee. Two opposing arcs-radius of which was not standard. This a sticking area for flat shouldered CIP standard adapter. There was no standard depth for where the shoulder started either. A foil cartridge worked just fine in these chambers, crush fit was simple. Modern brass tightly fits. When fired the brass expands, then contracts. The steel adapter does the same thing, but it doesn't contract enough. Result stuck or hung up adapter.

Shooting. Some say they get good accuracy with the adapter. I wonder. You are shooting a .454 diameter down a bore that has a .468/.471 size throat. Eight inches from the breech the throat tapers to .464. a .449 gauge will run the bore, a .450 will not. The minor diameter of the bore is .450. A .452 bullet will have about .001 engagement a side. With low power loads it might even spin, but with that little engagement it most likely with skid or strip.

I don't recall getting any accuracy with mine.

The loading process. I had to load a 45 Colt cartridge in the adapter. Then load the adapter in the chamber and fire. Then I extracted the adapter from the chamber. I recall a couple of times having to knock the adapter out with a rod, but most of the time the adapter came out. Then I to had drive the Colt case out of the adapter. I think I was using smokeless powder in the Colt cases. I think using black powder would have added fouling issues. I didn't get my adapter stuck, but it did hang up once in a while.

Tedious.

For the money that an adapter cost you can buy converted shotgun cases--more than one.

I said I don't recall getting any accuracy from the adapter.

Recoil of course was reduced. But I have always equated the experience of shooting an adapter in a Martini, about like kissing your sister or wearing rain coat to take a shower. No enjoyment there.

My advice, don't waste your money.