Gotta Love It. Love this QUESTION!! First a CAVEAT: I'm a retarded .. er retired .. yea, that it .. retired .. CAS Gunplumber. Other than basic knowledge, no rooster in this fight. SO:
If your shooting straight walled pistol cartridges (.38, 44Spl, .45) your going to get blow-by. Just a matter of degrees. .38Spl/357 very little. 44Spl/44 Russian/44Mag some and maybe problematic. .45 Colt/45 Schofield/C45S probably a lot and problematic. Some of the problem will depend on whether you choose that Heathen, Fad boring smokeless stuff ..... or Original Gun Powder and it's Subs.
If your choosing Uberti built rifles in .44Spl or 45Colt your going to get blow-by. Put that inna bank. The blow-by can be mitigated. With the 44 Special or 44 Russian, anneal your cases and Blow-By will go away. With 45Colt, anneal your cases and Blow-by will go away. Or, with 45Colt you can form 44-40 cases to 45Colt and Blow-By will go away. 45 Schofield and C45S may need to be annealed. "Others" will suggest a "Heavy" load and a big 'ol "heavy" bullet .. which may or may not help with Blow-By but will help lighten your wallet.
No matter. Your going to have FUN. Eventually, you will also probably end up with both calibers anyway. Or more. Resistance is Futile. You will be assimilated.
PS: For 45CS ... Actually it's Cowboy 45 Special or C45S, you'll need to play with your reloading die selection for best results. Regardless of what your read, hear, are told or suspect, 45ACP dies DO NOT produce good C45S loading.