Agreed. Using moonclipped or 45AR cases in a 45ACP revolver shouldn't contact the chamber's ledge/shoulder if the case has the proper length.
Here's some of the dimensions & clearances I documented before I converted that 45ACP cylinder to
45WSM
You can clearly see that moonclipped cases are closer to the frame breech, & the firing pin, & sit higher on the cylinder face.
That said, I almost never use moonclips in any or my revolvers that are rimless cartridges.
My M325/625s & M610 shoot reliably without them.
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Case head height above cylinder face, with case headspacing on chamber shoulder
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min length (.888") case= .067"
mid length (.893") case= .072"
max length (.898") case= .077"
w/plastic moonclips= .081"
w/metal moonclips = .083" (.040" thick metal moonclip)
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Headspace clearance:
(shell head to frame, with case headspacing on chamber shoulder)
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min length (.888") case= .030"
mid length (.893") case= .025"
max length (.898") case= .020"
w/plastic moonclips= .017"
w/metal moonclips = .013"
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Back to the roll crimp subject, while the vast majority of my 45 revolver handloads get a taper crimp, because of the bullets used, & irregardless of whether it's in an ACP or AR case, the ones that do have a cannelure (Sierra's 240gr JHC) do get a roll crimp with my Redding Profile Crimp die.
Some taper crimped loads are hard to keep from jumping crimp especially when it's a hot load in a lightweight revolver, like 45 Supers in a Sc framed revolver (325NG or 325TR).
Here using a re-sizing die with a smaller diameter can give you tighter bullet-case tension to help mitigate the bullet jumping crimp & creeping forward.
Years ago I was having this trouble & I found out that the RCBS TC sizing die I had been using for years had a .467" inside diameter (using my pin gages). Along with the nickel Remington cases I occasionally used, that had slightly thinner case walls, these loads easily jumped crimp even with when using minimal case mouth flaring before seating.
Both of the new Lee & Hornady dies I've bought since measure a tighter diameter, .465".
And the nickel plated cases? I trashed them. Never really cared for nickel cases anyway.
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Of course any roll crimped cartridge does need to be shot using moonclips or Auto Rim cases.
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