I have 4 moon clip revolvers, all Smith and Wesson, a 940, a 627 pc, and 2 625's. When you convert a rimmed case cylinder to a moon clip, you machine enough material for the moon clip to lie in, but the inner and outer sections of the cylinder are left alone. Therefore the rim of the case is still supported on 2 sections of the cylinder, 180 degrees apart, and the original headspace should not be changed, nor should it affect using speedloaders and normal handloading of the cylinder. After going the TK WEBSITE, and seeing that Clark Custom is
recommended for machining the cylinders I don't have much negative to say. Clark has always
done right by me. BTW if you happen to 0wn a 7 shot L frame S&W, the moon clip conversion is highly recommended, since high qaulity speedloaders are not made, not that HKS
are not good quality, but Safariland or any other high speed loaders do not make a product for this gun.