Driftwood Johnson
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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.
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.