I've got a 45 ACP Blackhawk conversion, but on the Navies anyway, there is not enough room on the cylinder, & possibly even the barrel would be too tight...
I am planning on building another set, on the 51 Navies, thinking about doing them in 44 American Bulldog, to match an antique pocket double I have ( my antique gun uses shortened 44 Special cases, with the rims thinned ) & my builder buddy thought we may need to go to a 5 shot cylinder on the 51 Navy...
or...
to keep it CAS legal for 5 rounds, we are looking at doing a 22 ish "safety" chamber for the 6th chamber & only dropping the hammer on that chamber leaving 5 safe rounds in the gun... of course the gun would not index on that "dummy" chamber, & would have to be placed there manually... we're actually still looking at the possibilities...
I'm sure you could possibly do 45 ACP on a Remington... I just love the balance & looks of the open top Colts...
