I don't have a lot of reloading experience, so I approached it from a mathematical and basic reasoning POV.
If I'm loading a 9mm 124gr RN bullet and I switch to a FPRN bullet, I reasoned that I should maintain the same seating depth to keep the case volume constant...the same amount of bullet should be pressed into the case.
Seating a shorter bullet to the same depth, should result in a short OAL. That difference in OAL should be the difference in the length of the bullets themselves.
As an example:
1. The 124gr RN bullet has a length, from base to tip, of .580"
2. The 124gr FP RN bullet has a length of .525"
3. The difference in length is .055
4. OAL of the RN cartridge is 1.160
5. Subtracting .055" from this should result in a new OAL of 1.105" for the FP RN cartridge
If I normally seat my RN bullets to 1.140", where I'm getting consistent velocities, I should be seating my FP RN bullets to 1.085"
I know my math is correct, asking if my reasoning for determining OAL sounds right to more experienced reloaders.
The powder being used shouldn't make any difference, as the volume stays the same, but I'm working with BE-86
If I'm loading a 9mm 124gr RN bullet and I switch to a FPRN bullet, I reasoned that I should maintain the same seating depth to keep the case volume constant...the same amount of bullet should be pressed into the case.
Seating a shorter bullet to the same depth, should result in a short OAL. That difference in OAL should be the difference in the length of the bullets themselves.
As an example:
1. The 124gr RN bullet has a length, from base to tip, of .580"
2. The 124gr FP RN bullet has a length of .525"
3. The difference in length is .055
4. OAL of the RN cartridge is 1.160
5. Subtracting .055" from this should result in a new OAL of 1.105" for the FP RN cartridge
If I normally seat my RN bullets to 1.140", where I'm getting consistent velocities, I should be seating my FP RN bullets to 1.085"
I know my math is correct, asking if my reasoning for determining OAL sounds right to more experienced reloaders.
The powder being used shouldn't make any difference, as the volume stays the same, but I'm working with BE-86