Other than the answer "it won't work", what is the technical

[Driftwood Johnson]

Howdy

A picture is worth a thousand words department.

Left to right in this photo the cartridges are 45 Colt, 45 Schofield, 45 Cowboy Special, 45 Auto Rim, and 45 ACP. The first three all have rims that are nominally .060 thick.

The 45 Auto Rim was developed as an alternative for revolvers chambered for 45 ACP. There is about .030 more clearance behind the cylinder in revolvers such as the S&W and Colt Models 1917. This was to accommodate the half moon clips.

In the 1930s when the 45 Auto Rim was developed, the rim thickness was set at .090, because that was the thickness required for the round to headspace on the rim and not slop around.

Here is a photo of a S&W Model 1917 and an almost full box of 45 ACP ammo mounted on half moon clips. You probably can't see it in this photo, but there is about .090 of clearance behind the cylinder to accommodate the ammo and the clips.

 

[44 AMP]

reason that you cannot shoot a 45 ACP (with moon clips) in a revolver chambered for a 45 Long Colt?

It has nothing to do with how far the bullet has to travel to get to the rifled barrel.

Lots of replies essentially hit part of the answer, lets see if we can pull them all together.

First, look at the dimensions of the two rounds. The .45 ACP specs 0.473" at the case mouth, 0.476" at the head, and 0.480" diameter at the case rim.

The .45 Colt specs 0.480" at the case mouth, is a straight case with a rim diameter of 0.512".

Since ammo is normally slightly smaller than the specs (to ensure easy & reliable chambering), a .45acp round might fall entirely through a .45 Colt chamber, even it not, it WILL go too deeply into a .45 Colt chamber to be fired, UNLESS something stops it. At the case mouth of the .45ACP round, the .45 Colt chamber is .007 oversize.

Now, this is a case where 007 is James Bond cool.

Does it work? yes. BUT, the acp brass will be bulged, and probably not suitable for reloading, or if it is, expect case life to be short. Like one to three reloads, maybe, then a split case. IF all that matters is the .45acp round fire ONCE firing it in a .45 Colt chamber will work, if the gun will take the needed clip.

(Note to those who DO have one of these guns, and RELOAD the .45 ACP brass fired from it, please share you experience!)

When the Army wanted .45ACP revolvers they wanted the chambers bored straight through, and half moon clips. The early S&W and Colt 1917s were made like that (which meant they were unusable without the clips), but S&W basically looked at that idea as stupid and very shortly went to making their guns with a chamber for .45ACP (having the ledge in the chamber for the acp case to headspace on. Colt soon followed suit, and after that all the 1917 revolvers (and those others made since, in .45acp) have been chambered for the .45acp, and so can be fired without the moon clips. IN those guns, all the clips do is give simultaneous ejection (which is ALSO a desirable thing).

A .45 Colt chamber CANNOT have the ledge to headspace .45acp. (if it did, .45 Colt would not chamber)

SO, in a .45 Colt chamber, the ACP is .007 undersize, and must "hang" from a clip in order to be fired.

UNLESS the gun is originally made to take one, or sufficient clearance is later machined into the gun, there is no place for the ACP clip to go.

The .45 Auto Rim, despite what many think, was never made for the military. It was a commercial round, brought out by Peters in 1920 as a convenience to the thousands of civilians who bought surplus 1917 revolvers, giving them a rimmed ACP case so they didn't need to use half moon clips.

 

[disseminator]

Already mentioned by Driftwood:

https://www.starlinebrass.com/brass...ce=eletter_170926&utm_content=order_now_35794

 

[gwpercle]

If the 45 Colt revolver is cut to fire 45 Colt rounds in moon clips then yes 45 acp in moon clips will also fire. I believe a certain model Ruger Redhawk is made just for this situation.
Just watched a video , the Redhawk that is marked 45 acp/45 Colt , shoots both rounds, the 45 acp are in thin full moon clips ( not the old army half moon kind) and the 45 Colt require no clips , a special ledge is machined in to hold the Colt rims...no clip required with them. Pretty cool setup !
Gary