The .45 Auto Rim in a .45 Colt revolver

[mcb]

Yes, 45 ACP ammo is often cheaper than 45 Colt ammo, that is a definite advantage. I'm not going to belabor the bit about fast reloads with clips any more.

When I bought this 45 Colt/45 ACP convertible Blackhawk in 1975 I did not care about the 45 ACP cylinder. Like the dope I was back then I tried to buy it without the extra cylinder. In fact, it was many years before I ever even used the 45 ACP cylinder. No, it is not for sale. Yes, I could probably shoot so called 'Ruger Only' loads in this revolver, but I ain't interested in that.

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Even though I have lots of Single Action revolvers chambered for 45 Colt, for some reason I have never been interested in Double Action revolvers chambered for the cartridge. Dunno why, they just don't interest me and I pass them by all the time. I much prefer my Smiths to be 44s. 44 Special or 44 Russian. Anyway, this Colt New Service that was made in 1906 is the only 45 Colt Double Action revolver I own. I bought it because it is so cool. Obviously I am never going to fire hot loads in it.

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I think, in this thread, it was my job to belabore the fast reload point. That was the reason I bought my S&W 625 was for those fast reloads. I had start USPSA Revolver division with a S&W 610 that fell into my lap with a deal I couldn't pass up. It worked well for a few years when I was learning the sport but finding good round nose 40 bullets conducive to those fast reloads was tough. I picked up a 625 and with 230gr RN it was like someone attached a shop-vac to the front of the cylinder, sucking in those short fat 45 ACP moonclips into the cylinder. In 2014 they changed the rules and my USPSA revolver is now a S&W 627 using 38 Short Colt but I still use my S&W 625 at the occasion club level match just because it is such a fun revolver to shoot.


S&W 625 5-inch (1989), California Competition cylinder release, SMD Fiber-optic front sight, and slightly modified Hogue round butt grip. Blade-tech holster, North Mountain Moonclip Holder.


Same setup S&W 627 PC 5-inch, California Competition cylinder release, SMD Fiber-optic front sight, and slightly modified Hogue round butt grip. Blade-tech holster, North Mountain Moonclip Holder.

 

[Jim Watson]

I wouldn't in
HIS New Service. The New Service was the basis for the Colt 1917 and was proofed for .45 ACP. But that is, as Slamfire would say, with a decade later metallurgy and a generation later action design than Driftwood's 1906 gun. I would take it easy, as he does.

I also recall that the .45 Auto Rim has a lower SAAMI maximum chamber pressure than ACP, it is NOT exactly the same thing except for the rim. Do you think they had learned something about the strength of the 1917s by 1920?

 

[Vern Humphrey]

I wouldn't in
HIS New Service. The New Service was the basis for the Colt 1917 and was proofed for .45 ACP. But that is, as Slamfire would say, with a decade later metallurgy and a generation later action design than Driftwood's 1906 gun. I would take it easy, as he does.

I also recall that the .45 Auto Rim has a lower SAAMI maximum chamber pressure than ACP, it is NOT exactly the same thing except for the rim. Do you think they had learned something about the strength of the 1917s by 1920?

My New Service was also made in 1906. It had been reblued and aggressively buffed, so I had no qualms about trimming the barrel to 5 1/2", mounting adjustable sights, and putting on Herritt's Shooting Master grips -- the result is a VERY handsome revolver. I like 13 grains of HS 6 and a 255 grain wide flat nose bullet, "lubed" with Harbor Freight red powder coating.

 

[Jim Watson]

Ah, for the good old days, when you could monkey with surplus and used guns.
Frank DeHaas took a side trip from rifles to revolvers with a 1917. Made his own adjustable sights, but the far out alteration was to cut the frontstrap loose from the frame at the top and bend it down to weld about halfway down the back of the trigger guard. No filler grip or grip adapter required... but he did have to make unique stocks for it.

 

[mcb]

Interestingly SAAMI has never updated 45 AR. The table for the older Copper Units of Pressure list 45 ACP at 18,000 CUP and 45 AR at 15,000 CUP but no measurement for 45 ACP +P . When you look at the modern Transducer table you find 45 ACP at 21,000 psi, 45 ACP +P at 23,000 psi and no measurement for 45 AR.

 

[Jim Watson]

I don't know how much trouble it is to convert from crusher to piezo transducer but have to think it is more expensive than they think it is worth for such a low volume caliber.

 

[Vern Humphrey]

I don't know how much trouble it is to convert from crusher to piezo transducer but have to think it is more expensive than they think it is worth for such a low volume caliber.

It can't be done -- there is no conversion formula, and if you compare SAAMI CUP standards to more modern PSI, you see there is no pattern.

 

[Merle1]

First Colt 1917s had through-bored chambers, without the internal step-down.
They would not headspace ACPs without clips.
At some later point, the chambers were properly bored with the stepdown that would headspace ACPs on the case mouth, and those guns could fire without clips.

Smiths used to reliably headspace ACPs without clips, but in recent years you couldn't count on it.
Older ones do, newer ones are questionable.

As for the clips- many of us simply don't like the additional hassle.
The idea of using Auto Rims to avoid clips is perfectly valid.
Denis

when I had this problem with my M625 I discovered that many of the new, unfired cases were well short of the "trim to" length; couldn't expect those short cases to headspace without a moon clip!

 

[DPris]

I was firing factory ACP ammunition in three different newer Smiths & kept getting rounds of differing makes that'd misfire with light, or no, firing pin indents in some chambers.

In my older 625, and an older limited-edition Heritage blued 25 variant, I've never gotten a single misfire when shooting without clips.
Denis

 

[Vern Humphrey]

One problem is, .45 ACP cases get shorter, not longer with firing. And that's why reloads are unreliable when used without the half moon clips.