chamber dimensions .45 ACP revolver

[krtlesfd]

I've done the usual and trawled the web several times, including a search on this forum, but still come up empty-handed. That leaves me no option but to ask and hope someone can provide me with the information. I'm trying to find the dimensions, hopefully a proper dimensioned drawing, of the chamber of a .45 ACP revolver. Something that was professionally designed to use ACP, not some quick conversion job. Smith and Wesson have manufactured several successful models for this cartridge, and there's not much anyone can tell S&W when it comes to revolver design, so I'd like to use theirs as a model. Can anyone direct me to such drawings, assuming they exist anywhere outside the S&W drawing office?

Note: Please don't bother with the obvious idea of taking a .45ACP revolver and just measuring it; that's not an option where I live, but thanks anyway. Besides, a dimensioned drawing is a better starting point.

 

[505Gibbs]

I highly doubt that factory blueprints have 'left the building' short of theft!
Possible but NOT likely.
In any case, short of taking measurements or worse cutting a cylinder up & then measuring I don't see a lot of alternatives.
S&W will usually fire perhaps haphazardly without the moon clips but the intention always was their use so head spacing is part of the equation as you're aware.
We'll see what others offer up.
Why the questions - some elaboration might aid the responses?

 

[alwslate]

The old NRA handloading manual showed drawings of case and chamber dimensions of all common calibers. But the chamber dimensions for the .45 should really be the same for revolvers and semi autos. Research NRA publications. Maybe their manual is still available.

 

[alwslate]

You don't say what your problem, if any, actually is. But realize that chamber specs are for ctgs, not for specific guns so S&W chambers for the .45 acp should be in line with standard industry dimensions. But...several years ago there were some models of S&W revolvers made in .45 acp that had chambers without much of a leade that made shooting hand loads with heavy SWCs impossible. If you have one getting the chambers properly recut should be a simple job for a good gunsmith.

 

[armorer951]

The SAAMI specs and drawings are here......

SAAMI

 

[mikerjf]

Didn't many/most of the early 1917's (both S&W and Colt) have bored-thru chambers with no rim lip? So that a non-mooned cartridge would just fall thru? Dunno if "professional" is exactly the right word…

 

[krtlesfd]

The SAAMI specs and drawings are here......

SAAMI

Thank you, armorer951, that's exactly what I need. I knew about SAAMI drawings for cartridges, but I was unaware that they provided them for chambers as well. Much appreciate that!

 

[Muley Gil]

Didn't many/most of the early 1917's (both S&W and Colt) have bored-thru chambers with no rim lip? So that a non-mooned cartridge would just fall thru? Dunno if "professional" is exactly the right word…

Approximately 50,000 of the first 1917 Colts had chambers that were bored straight through, requiring the use of half moon clips. I have read that Colt replaced most of these cylinders later on. I have also read that some S&W 1917s had straight bored chambers, but I've never seen one.

 

[BLUEDOT37]

S&W will usually fire perhaps haphazardly without the moon clips but the intention always was their use so head spacing is part of the equation as you're aware.

S&W wouldn't waste their time & effort cutting shoulders in their revolver's 45ACP chambers if they didn't intend them to be used for the purpose of headspacing individual cartridges without moonclips.

Otherwise they'd just cut them like they do for all of their rimmed cartridge revolvers, with chambers that transition from a leade to the throat, & without any shoulders.

I rarely use moonclips on any of my late model S&W 45ACP or 10mm Auto revolvers & they all are reliable without moonclips.

Revolvers that aren't consistently reliable without moonclips usually have tolerance/clearance issues that need attention &/or are using handloads assembled using poor practices.

.

 

[glowe]

Here you go. Page 49 SAAMI.

 

[krtlesfd]

I got it, thanks glowe.

 

[Hondo44]

I got it, thanks glowe.

When I use the link furnished above, the two .45 ACP drawings are on pages 56 and 57. And the .45 Auto Rim is on page 58. But glowe's photo shows page 49, I can't explain that.

Regardless, since you want S&W's specs, you'll want to refer to page 58 because that's the way S&W cuts their chambers; with a square shoulder.

Both pages 56 and 57 show a tapered shoulder, and so does glowe's page 49; not correct for a S&W.

 

[StakeOut]

There are the specs and then there is reality.
S&W produced a lot of .45cal revolvers before 1982? that had cylinders bored larger than the specs.

 

[reddog81]

There are the specs and then there is reality.
S&W produced a lot of .45cal revolvers before 1982? that had cylinders bored larger than the specs.

True! SAAMI is a great guideline, but don't bet your life that every single firearm out there matches their specs.

 

[Hondo44]

Agreed. All manufacturing machining of old has specifications but also tolerance specs that provide acceptable variations from the specs. Tolerances allow for deviations in cutting tools due to wear.

Pretty much eliminated in the case of MIM parts making however.

 

[BLUEDOT37]

When I use the link furnished above, the two .45 ACP drawings are on pages 56 and 57.
But glowe's photo shows page 49, I can't explain that.

Page 56/57 references are from the 2015 SAAMI manual but the page 49 reference is from an older SAAMI manual, 1993 for one.

.

I agree, it's a head scratcher why the 45AUTO drawing shows a tapered leade before the throat but the 45AUTO RIM drawing shows a square shoulder at the throat in their drawings. Just the opposite from what I'd expect to see.

.

 

[gwpercle]

The SAAMI specs and drawings are here......

SAAMI

This is the correct answer . SAAMI specifications .
All manufacturer's use these dimensions and notice there are allowable tolerances for manufacturing .
But these dimensions are the standard .

Good Post Hondo44 !
Gary

 

[StrawHat]

SAAMI was founded in 1926 or thereabouts. S&W had been making ACP revolvers prior to that, 1917.

There should be a difference between a 45 ACP chamber drawing for a pistol and one for a revolver.

Kevin

 

[Hondo44]

Yes, SAMMI should have a drawing of chamber specs for 45 ACP that show a square cut chamber shoulder for revolvers and autos, like they have for the 45 AR on page 58.

Because all of my 45 ACP S&W revolvers and Colt 1911 autos are the same; they have square chamber shoulders. I don't know what ACP handguns have tapered shoulders, if any.