Hi superc,
One might reasonably think so, but in practice, so long as the .45 LC Cartridges are standard Loads, I do not expect any danger of Case rupture at the rear in the for-them over-generous Head Spacing in an otherwise correctly head-spaced for the .45 ACP Revolver, when able to chamber the LC Cartridge.
I've fired hundreds of rounds of both .45 LC and .45 ACP in one of my Model 1917 Colt New Service Revlovers which accepts either Cartridge, and never had a misfire or light Primer strike with the LC. Never seen any hint of 'bulge' at a Case base. All LC Primers always appeared to have received a sound strike with a good dimple.
Now, I'd certainly expect a reduction in accuracy, when shooting .45 ACP from a Cylinder which also accepts .45 LC, since the Bullet has to travel a little longer ways with Gas going around it, then having however so, to center itself and meet the forcing cone, along with what ever else, which in a 'snubby' would not matter, but in a Target Gun or Long Barrel, would matter, or would when it would, for accuracy over distance.
I have heard and have read, that some Model 1917 New Service came with Fatory Cylinders which accepted either Cartridge, but that this feature was discontinued early on, to be strictly .45 ACP instead...about as your mention.
So personally, yes indeed, I would definitely favor having two respective Cylinders for wishing to shoot both Cartridges in the same Revolver as the 'best' way to go...if one has any intention of ever shooting accurately over any distance with the .45 ACP.
Probably, the design of the Fireing Pin being part of the Hammer, reaching deeply with no problems, as it is with the 'New Service' alleviates the concern of the same Cylinder allowing a good smart strike for both Cartridges, even with over-generous head-space resulting for the LC, but on Revolvers of other make, their Firing Pins may not.
If it is a 'New Service', where the Firing Pin has no issues with reaching either Cartridge Primer well, or managing even with the LC being able to be at any pisition fore or aft in the space, and if it is a 'Snubby' or 'Belly Gun' - as mine is - then to me it would not matter if the Bullet wobbles a little and had Gas going past it as it finds it's way to the forcing cone.
But for a Revolver one wishes to be accurate over distance, I'd say, if no Factory Cylinder is available for the .45 ACP, then I'd expect an able Smith could rebore and modify a Cylinder of the next smaller Callibre, to be a perfect solution.
Phil