In the 4053 (using the converted slide and bbl in 10mm), after trying several heavier outer springs with hardball practice ammo, the combination of the 21 pound Wolff recoil spring (#47721) and the OEM inner spring seems to give the proper resistance to allow the slide to reach the point where it will just lock back on the last round, but not impact the frame. There is still the approx. .0125" of travel available past the catch on the slide stop assembly with the springs installed, so I don't think the slide is bottoming out/damaging the springs.

Tactical Springs (tacticalsprings.com) also makes an inner/outer spring combination for the 4516-2 that will work in the gun.

Set up for factory Hornady "duty" or carry ammo requires changing over to a Wolff 23 pound outer spring, part# 47723. I believe these two Wolff recoil springs are actually for the 4513. It's a chore getting the slide to lock open with the heavier spring combination.

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Ret. LE, FA Instr, S&W Armorer