Kuyong_Chuin
Member
I was sorting through my brass and ran across an old all in the mix that ended up being a 38 Super. It got me looking at the data for that round and since it uses the same bullet as the 9mm I started comparing the two and got very confused about something I wish someone would explain to me. You have two rounds that use the same bullets and the same powders but ones starting load is at or a little over the max of the other. What is confusing me is how when loaded with the same 115 grain XTP bullet and the same powder how is it that the 38 Super using more powder is just a little faster or even slower using more powder. Example: 9mm 115 grain XTP bullet loaded to max with 6.0 grains of Longshot has a listed speed of 1203. Using the same bullet and powder but loading the starting load for the 38 Super of 6.5 grains has a listed speed of 1214 only a 11fps increase for 0.5 grain increase in powder. Using HS6 it gets even worse, 9mm loaded max load of 7.0 grains list speed of 1234, 38 Super starting load of 7.8 grains list speed of 1212 fps. This makes no since to me, how can you use the same powder and bullet but more of it and it get slower. Unless it is because of the longer case there is not as much pressure even using more powder to push the bullet. Someone please enlighten me if it is just because of the longer case or something else is going on. Also I like to know the pros and cons of the two rounds.