Buffalo Bore is now manufacturing the .45 Auto Rim in four loadings: two standard pressure and two “+P”.
In standard pressure, you can get a 200 gr JHP at a little over 1000 fps (444+ ft-lb) out of a 4″ S&W revolver. The 255 gr hard cast FP is clocking almost 870 fps (410+ ft-lb) out of the same 4″ Smith.
With the “+P” designation, the 200 JHP is sizzling at almost 1200 fps (635 ft-lb) out of the 4″ S&W. The hard cast 255 gr FP is moving at more than 1030 fps (570+ ft-lb). These are amazing numbers. It should be noted that there is not a SAAMI specification for “+P” in the .45 Auto Rim. Consequently, use only a modern firearm with the +P ammunition. Buffalo Bore does state that the +P loads are safe to use in all post-WWII revolvers chambered for the .45 ACP.
Buffalo Bore uses virgin Starline brass and low flash powder. Â It is not clear which bullets are being used in these loads, but Buffalo Bore tends to use quality JHPs for self defense loads.
In recent years, there has been a rise in interest in revolvers chambered for the .45 ACP. The .45 Auto Rim is essentially a rimmed version of the ACP, allowing the shooter to shoot similar loads without the need for moon clips.  In other words, these rounds drop into a .45 ACP chambered revolver just as a regular rimmed .38 Special round works in a .38 Special chambered revolver.  For reloaders, having the brass for the auto rim cartridge has provided them an easy way to shoot these guns without the need for full- or partial-moon clips.  If you’ve ever shot a gun that required any kind of clips, you know it is a pain to fiddle with the darn things.
In the past, the .45 Auto Rim has not had a large following, partially because of the lack of quality ammo loaded for it. However, these loads from Buffalo Bore appear to be very powerful loads. They should capture the attention of the .45 revolver enthusiasts.