I've seen references here & there about the capacity similarities, & differences, of these three cases, but these have always just been more hearsay, & not from a published source. Also, since I have a Mdl. 1911 setup to handle 45 Super loads & new 45ACP S&W "N" frame revolver, I also wondered about how the strength of the Super & Auto Rim's compared in my Starline cases. 45 Super data & hot 45 AR load data is not very extensive, especially when it comes to powder & bullet manufacturer's load manuals & I wanted to be able to use what data I have in one another, but again wondered about the capacities & if that should be a factor.
I decided to send an email to Starline & asked how the internal case capacities compare between these three. They said the capacities vary quit a bit from lot to lot but they're all around 26grs. of water. Not exactly the detail I hoped for. I replied, reiterating my original question & additionally asked how their case strengths compare. Again, an answer without much detail or specifics. Starline's website states that their 45 Colt cases are "tested to 44 Magnum pressures" (which I've loaded mine to in my Ruger SRH 454 Casull) & that their 45 AR cases are built with the "same integrity" as their 45 Colt cases, which led me to check for myself and see if a ".45AR Super" was doable.
Whenever I need new cases my first choice is Starline because they have the best availability, strength & pricing, which is what I used for this comparison, and I had all brand new cases of each. I've never checked the water capacity of a case before but I decided on using a same dab of plumber's putty in the primer pocket & pushing it in until it filled the flash hole completely. I sat the empty case on my electronic powder scale & zeroed it out, then added water with a dropper until it was to the top. I tried to be as consistent with each as I could & checked a couple of each type. The surface tension of the water causes it to dome up above the rim noticeably, long before it'll overflow, so I only added to a point that represented a full case, not an overfull one. I came up with the following: 45ACP @ 27.3 grs., 45AR @ 27.4grs., & 45 Super @ 26.8grs. So the ACP & AR are essentially the same & the Super case has about 0.5grs., or 2% less capacity.
I already had 185gr. & 200gr. JHP Super loads established for my 1911 (got the data from "Project 45 Super", at RealGuns) & knew they shot fine in my revolver using moon clips & S-L Super brass. Since the S-L AR brass actually has a little more capacity than the S-L Super brass I was comfortable working up, from an ACP +P powder level to the same Super powder level, using all the same components (Hornady XTP JHP .451" bullets with heavy taper crimp, CCI 300 primers, & Power Pistol powder carefully weighed individually) as used in the Super brass. The only other difference was the cartridge OAL. Since my revolver's chambers don't have the same restriction as my 1911's chamber does (the cartridges for my 1911 have max. OAL of 1.200" with these bullets because of the short freebore/leade before the bullet ogive hits the rifling) I seated the bullets in the AR loads out to 1.255" OAL. I worked up to my established Super maximum with no problems. The higher velocity, light weight bullets have a lower point of impact than anything else normally shot, but that's to be expected. The full house Super loads, using Power Pistol, sure gives a nice "light display" out of my short barrel. I like!! I plan on loading a box or two & only use these when the "urge" hits (& shoot my .454 when I wanna really get a thrill), but these are serious loads from a 45ACP form & widen the range of this fun cartridge in a revolver.
This info may exist elsewhere, but I haven't run across it in all my searches for 45 Super or Auto Rim articles. I thought I'd post this in case someone else was interested in it too & can find it helpful. Of course your situation/equipment may differ from mine so approach any changes for you cautiously & only use these in modern large frame revolvers in good condition. You know the disclaimer.
I decided to send an email to Starline & asked how the internal case capacities compare between these three. They said the capacities vary quit a bit from lot to lot but they're all around 26grs. of water. Not exactly the detail I hoped for. I replied, reiterating my original question & additionally asked how their case strengths compare. Again, an answer without much detail or specifics. Starline's website states that their 45 Colt cases are "tested to 44 Magnum pressures" (which I've loaded mine to in my Ruger SRH 454 Casull) & that their 45 AR cases are built with the "same integrity" as their 45 Colt cases, which led me to check for myself and see if a ".45AR Super" was doable.
Whenever I need new cases my first choice is Starline because they have the best availability, strength & pricing, which is what I used for this comparison, and I had all brand new cases of each. I've never checked the water capacity of a case before but I decided on using a same dab of plumber's putty in the primer pocket & pushing it in until it filled the flash hole completely. I sat the empty case on my electronic powder scale & zeroed it out, then added water with a dropper until it was to the top. I tried to be as consistent with each as I could & checked a couple of each type. The surface tension of the water causes it to dome up above the rim noticeably, long before it'll overflow, so I only added to a point that represented a full case, not an overfull one. I came up with the following: 45ACP @ 27.3 grs., 45AR @ 27.4grs., & 45 Super @ 26.8grs. So the ACP & AR are essentially the same & the Super case has about 0.5grs., or 2% less capacity.
I already had 185gr. & 200gr. JHP Super loads established for my 1911 (got the data from "Project 45 Super", at RealGuns) & knew they shot fine in my revolver using moon clips & S-L Super brass. Since the S-L AR brass actually has a little more capacity than the S-L Super brass I was comfortable working up, from an ACP +P powder level to the same Super powder level, using all the same components (Hornady XTP JHP .451" bullets with heavy taper crimp, CCI 300 primers, & Power Pistol powder carefully weighed individually) as used in the Super brass. The only other difference was the cartridge OAL. Since my revolver's chambers don't have the same restriction as my 1911's chamber does (the cartridges for my 1911 have max. OAL of 1.200" with these bullets because of the short freebore/leade before the bullet ogive hits the rifling) I seated the bullets in the AR loads out to 1.255" OAL. I worked up to my established Super maximum with no problems. The higher velocity, light weight bullets have a lower point of impact than anything else normally shot, but that's to be expected. The full house Super loads, using Power Pistol, sure gives a nice "light display" out of my short barrel. I like!! I plan on loading a box or two & only use these when the "urge" hits (& shoot my .454 when I wanna really get a thrill), but these are serious loads from a 45ACP form & widen the range of this fun cartridge in a revolver.
This info may exist elsewhere, but I haven't run across it in all my searches for 45 Super or Auto Rim articles. I thought I'd post this in case someone else was interested in it too & can find it helpful. Of course your situation/equipment may differ from mine so approach any changes for you cautiously & only use these in modern large frame revolvers in good condition. You know the disclaimer.
Last edited:
I've been loading my 185 JHPs with 11.3grs. of P-P. These are supposed to be about 1400fps, which is 804ME, out of a 5" 1911. That seems a bit high comparing it to the scant related data out there? But that is a lot of powder. No idea what they'd be in a revolver. I got started using P-P for the Super & then started using it to load +Ps in my sons' 40S&W & 9mm Luger, which they really like. Yeh, I like a good muzzle flash too (don't blink or you miss the show!). Nice photo!! 
