My goal is 800 fps with a 230 gr bullet in the 1911. This is the velocity specified for the original 1910 cartridges in the testing and development of the 1911. The first recorded military load was 5.0 grains Bullseye with a 230 FMJ.
early loads
later loads
I don't have pressure gauges and nit noids will argue that velocity does not equal pressure, and they are more or less right. However, in this application, you have to take into account slide speed. The faster the bullet, the faster the slide recoils. Too fast a slide recoil and function issues will rise, and the pistol gets beat up. Incidentally, too slow a slide speed, and function issues show up too.
So, I wanted to find a Unique load that gave me a muzzle velocity of 800 fps and I came to the conclusion that 5.5 grains Unique would do this. I remember reading and hearing that 6.5 grs was considered a maximum, and given that the velocities were above 900 fps, I agree. I have shot commercial ammunition that had a 230 gr bullet and that stuff pushed the bullet around and above 900 fps. But I don't want that.
If you use mid range loads, don't worry about pressure or velocities issues due to a seating depth of 1.24" versus 1.250". Go for the seating depth that ensures reliable feed.
Kimber Custom Classic
230 LRN Valiant
5.5 grs Unique lot UN331 1989 Mixed brass WLP (brass)
OAL 1.250" taper crimped 0.469"
16-May-09 high 83 °F
Ave Vel = 827.4
Std Dev = 17.63
ES = 85.68
High = 871.6
Low = 785.9
Number rds= 31
230 LRN Valiant
6.0 grs Unique lot UN387 6/21/93 Mixed brass WLP
OAL 1.250" taper crimped 0.469"
18-Mar-07 T = 62 °F
Ave Vel = 898
Std Dev = 21.44
ES = 75.58
High = 944.3
Low = 868.7
N = 25
accurate lots recoil 15' foot ejection
230 LRN Valiant
6.0 grs Unique lot 6/21/1998 Mixed brass WLP (nickle)
OAL 1.250" taper crimped 0.469"
16-May-09 high 83 ° F
Ave Vel = 885
Std Dev = 16.79
ES = 67.26
High = 917.8
Low = 850.5
N = 30
strong recoil 15' foot ejection
230 LRN Valiant
6.5 grs Unique lot UN387 6/21/93 Mixed brass WLP
OAL 1.250" taper crimped 0.469"
18-Mar-07 T = 62 °F
Ave Vel = 926.4
Std Dev = 16.64
ES = 71.16
High = 963.4
Low = 892.3
N = 32
light leading accurate centered hard recoil 20 foot ejection