possible m1917 british proof marks

[Remyshooter]

There's a faint capital 'P' still on the the back face of the cylinder at the 12 o'clock position in the first pic. *** a 'U' stamped on the back face at the 1 o'clock position,,also very faint now.
But I don't see any remnant of a ser#.

Don't know about that, think it is a trick of light, shading, and pitting/wear. See new pics.

 

[Oyeboteb]

Unfortunately, in theory anyway, .45 ACP is a little too stout for what the .455 Series of Revolvers were rated for or made for.

The .455 Cartridge was a lot lower pressure that the .45 ACP, and, for that matter, so is .45 Colt.

'SAAMI' for .45 ACP is 21,000 PSI

For .45 Colt, it is 14,000 PSI

.455, while not having any easily discoverable 'SAAMI' peramiters, I will guess, was/is likely about 12,000 PSI or maybe, 14,000 tops.


Not saying one can not fire .45 ACP in the 'converted' Revolvers, nor that many people have done so of course with seeming impunity...

Just saying, it is about on par with firing 'Proof Loads' when one does.

The Model 1917 were built for the higher pressure, and, their Cylinders were specially Heat Treated.

Otherwise, the .455s are definitely an example of when S&W was at their pinnacle of qualty and workmanship, and are very fine Revolvers.

I have one myself which I am very fond of, and, mine has been 'converted' also, as so many were.

 

[2152hq]

I can still see the 'P' in the first 2 pics/second set, of the rear of the cylinder.
The first pic is clearer of the two. In that pic the P is now at 1 o'clock,,U (much fainter) at 4 o'clock and upside-down.

No matter, I wasn't entirely sure from reading the thread what the cylinder was chambered for now.

As a 45acp,,take it easy on it and it'll give great service for years to come.