As a similar test, I loaded 38SPL cases with primer only and a foam ear plug.

Shot through my SW Model 14-3. Worked well and would punch a hole in cardboard at 20ft. Not very accurate, 6 inch groups.

Primer only was still very loud.

I tried some primer/ear plugs in various 9mm pistols. Would not cycle the gun, but worked well as a single shot.

Very loud in a garage.

I pulled the bullets in 22LR (CCI standards) and cut foam ear plugs to fit. Not to loud, but less accurate.

Try at your own risk, your mileage may vary.

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USAF, Ret.