45 acp.....185 gn Lead SWC.....Colt Series 70 Gold Cup National Match
Does this gun have any type of optic sight mounted on it? Usually 3.5 gr. BE will work for open sights. A heavier charge is needed if there is a slide mounted sight - usually in the 3.8 to 4.2 range.
45 acp......185 gn Lead SWC.....Smith & Wesson Model 25-2
You can go lower, say 3.0 gr. of BE.
Question: What are my chances that the same powder charge will work for both 45 acp guns?
3.5 gr. will work in both guns, assuming the M1911 is open-sighted.
38 spl......148 gn Lead HBWC...Colt 1960's Vintage Gold Cup National Match
2.5 gr. should work well in this gun, depending on the strength of the recoil spring. If it doesn't, try 2.7 gr.
38 spl......148 gn Lead HBWC...Smith & Wesson Model 14-2
2.5 to 2.7 gr. will shoot well in this gun.
Question: What are the chances that the same powder charge will work for both 38 spl guns?
Yes, see the above info.