Interesting modifications. If I ever find a 3913 at a decent (cheap) price, I'm going to give the DAO modification a shot.

Since, thanks to you, I was able to do the 457DAO modification, I know what needs to be done. And, also thanks to you, I have the firing pin retainer that will work.

The grip mod is interesting, but I'd need to see pictures of the parts you fabricated to even be able to think about doing that.

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Can open, worms everywhere.