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Discussion Starter · #1 ·
I have a Ruger P4 semi-auto, blowback type carbine in 40 S&W that performs so well that I am thinking of a simple project using the 357 Sig in the P9.

The P9 is 9mm, same as the 357 Sig, nad differs from the P4 only in the weight of the bolt assembly and the bore diameter. Is it possible, or even wise, to ream a P9 chamber out to 357 Sig, and drop in the 40 S&W bolt assembly?

Since this is frequently done in handguns that shoot both the 40 and the 357, I am guessing that it should work well.

With Longshot powder 124 gr XTPs should hit 2000 fps from the 16.25 inch bbl, and 147 XTPs about 1750, so its worth attempting on an experimental basis.

However, i am not a gunsmith, and this will take a small investment during hard times, so please advise me regarding feasibility.

· Inactive account
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Since the average operating pressures of the .357 Sig are higher than the 9mm, I would venture to guess that the lighter bolt in your P9 would not stand up to the beating from the .357 Sig. I would opt to re-barrel the P4 to .357 Sig. Although the pressures for the .357 are higher than the .40, as an example, barrels in .357 Sig and .40 S&W are interchangeable in the Sig P229 with no other modifications. .357 Sig ammo even works in .40 S&W magazines. Just my personal experience.

Allen F.
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