I was recently given a S&W M-1917 revolver in .45 ACP. I believe this was my late father-in-law's police service revolver. It came with two full-moon clips but the cartridged appear to headspace properly without them. Other than for case ejection, do I really need these awkward darn things to shoot it? My understanding is that the .45 Auto Rim cartidge is no longer available.