!!Lead Cast bullet vs FMJ Seating depth pressure question and discussion!!
!!Lead Cast bullet vs FMJ Seating depth pressure question and discussion!!
Have some questions:
Data:
1. Lee 124 grain TC tumble lube 9mm Luger lead (wheel weight) cast bullets are Diameter: .355" lube grooves and .358" base.
2. Lee 124 grain TC tumble lube 9mm Luger lead (wheel weight) cast bullets are bullet Over all length (OAL): .578" Long.
3. 9mm Luger rounds loaded with Lee 124 grain TC tumble lube 9mm Luger lead (wheel weight) cast bullets are taper crimped to: .377" on case mouth (were the round head spaces in the chamber).
4. Winchester 115 grain FMJ round nose (reloading components) are Diameter: .354".
5. Winchester 115 grain FMJ round nose (reloading components) are bullet Over all length (OAL): .587" Long.
6. Original factory PMC 9mm Luger round is crimped to: .377" on case mouth (were the round head spaces in the chamber).
7. Original factory PMC 9mm Luger round is over all round length (OAL): 1.155" (OAL).
8. Reloaded 9mm Luger rounds loaded with Lee 124 grain TC tumble lube 9mm Luger lead (wheel weight) cast bullets are over all round length (OAL): 1.044" (OAL).
Is this normal? Specially the OAL of the rounds are considerably different. Original factory round has OAL of 1.155" and the reloads with cast bullets have OAL 1.044".
I had to seat the cast bullets deeper since they did not go all into battery since pieces of lead of the bullet was getting between the case mouth and chamber headspacing not letting headspace both. I seated the lead bullets deeper and then the headspacing Problem was gone similar to this YouTube Video: https://www.youtube.com/watch?v=POIBBivXPww.
Will there be an pressure issue? Case Volumen is reduced seating the cast bullets deeper but at the same time I load for cast bullets 3.3 grains of powder while for FMJ bullets I load 4.3 grains of powder. So empty airspace Volumen in the case should be equal again with the reduced powder Charge on this heavier cast bullet. I guess empty airspace Volumen is equal again and therefore should be the pressure (PSI or CUP) since P*V=n. P=pressure, V=Volumen of the case and n=powder Charge. Therefore: P=n/V while temperature is a constant as well crimping is considered constant and bullet weigth is variable but a constant since neutralised by reduced powder charge.
P (lead cast Lee 125 grain)=-n/V [more bullet weight but less powder. Case empty volumen equal].
P (FMJ 115 grain)=+n/V [less bullet weight but more powder. Case empty Volumen equal].
Is this my reasoning Logical? Will there be an higher pressure or not?