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I shot an AMT .45 Backup a few years back and though the reliability suffered with this particular specimen, it was very small for a locked breech 45. Recoil was not severe probably due to the lock design and all stainless steel construction. I would not be surprised to see a similar sized version of an R45. Hook up with Mouseguns.com to find a general idea of the size of the AMT. Once your there click on the first sub-heading : Pocketgun chart by BOB O