Appreciating the responses. Based on them, I think I'd be most comfortable with a .357 Sig barrel in a .40 P229 or a Glock 23, since the gun is basically the same with a slightly narrower barrel (inside, same exterior dimensions). The .40 case being necked down to .357 would let the magazines, extractor, etc. all function the same.
Beretta PX4; 92FS; 92S; 8040G | Rock Island GI 1911 | Sig Sauer SP2022; P6 | Colt Python 4"; 1968 Detective Special 2"| Smith & Wesson M642 No-Lock | Ruger LCP; 10/22 | Daniel Defense M4V1 | Remington 870 | Alpine M1 Carbine | Steyr M1895 |1943 Izhevsk Mosin M91/30 | Walther PPS