That seems awfully low. I get just at 800 fps with 4.5 grains Bullseye with a LRN with three different lots of Bullseye. I have, but have not chronographed plated bullets at this time.
The low velocity could be due to off axis errors in shooting over the chronograph. I plumb my Chrony and shoot a reference load precisely because of off axis errors with the thing.
Code:
Kimber Custom Classic
230 gr LRN Valiant 4.5 grs Bullseye lot BE532 (80's mfgr) Mixed Brass WLP (brass) OAL 1.250" taper crimp .469"
16-May-09 high 83 °F
Ave Vel = 782.7
Std Dev = 13.41
ES = 52.05
High = 815.5
Low = 763.4
N = 28
230 gr LRN Valiant 4.5 grs Bullseye 99' & 2005 mixed lot Mixed Brass WLP (brass) OAL 1.250" taper crimp .469"
16-May-09 high 83 °F
Ave Vel = 805.2
Std Dev = 38.07
ES = 136.9
High = 912.4
Low = 775.5
N = 24
230 gr LRN Valiant 4.5 grs Bullseye lot 827 (60's/70's powder) Mixed Brass WLP (brass) OAL 1.250" taper crimp .469"
16-May-09 high 83 °F
Ave Vel = 822.9
Std Dev = 14.14
ES = 55.24
High = 853.7
Low = 798.4
N = 26
