I'm with Ozzieman.
The Colt unit I purchased about 12 years ago is superb, and probably has 10,000 rounds through it. The fact that it locks open on the last round and actually does generate some recoil are its best features. Other units do not lock open on the last round because they are aluminum and the slide stop notch would get battered by the steel slide stop.
When I shoot my SIG P229 with its conversion unit in place, its quite light in the hand and there is almost no recoil to train with. To my hand, the Colt unit's recoil is only a little bit less than a 9mm Government model in the same frame.
Think about shooting 3,000 - 5,000 rounds of .22LR in a pistol of the same weight as a fully loaded .45 ACP, with the same grips and trigger and what that will do for your shooting. That's why the one-and-a half pistol argument is not relevant, given that to switch slides takes well under a minute even if you are missing a couple of fingers. How many pistols can you really shoot at once, anyway?
You will never lose money on the Colt unit. Try for one starting at about $400 and go up incrementally until you get one.
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