245 gr Barnes Spitfire and 285 gr Spitfire question

[jontom]

I usually don't post, because I am a novice. However, from reading the posts on this site I have learned allot.

Last weekend, I was testing the 245 and 285 Spitfire.

Synthetic Stainless 10 MLII
Winchester 209 Primers
43 grains of SR 4759 measured
factory supplied sabots
90 degree heat
100 yds

The 245 Spitfire formed a 1 7/16 group after 3 shots. I then tried the 285 Spitfires. 1st 2 shots where approx. 1/2 inch. The next 2 shots didn't hit the target. I notice both shots hit the ground approx 30 yds from the target.

I shot the 245 Spitfire a fourth time, hitting right in the 1 7/16 grouping. I am shooting approx 3 1/4 inches high at a hundred yards. I moved the target out to 200 yds. It hit 3 inches to the right at 3 o'clock.

My question is what happen with the 285 Spitfires? I used the same procedure and time between all the shots. I thought that the 285 Spitfires were going to be my hunting load after the 1st 2 shots.

jontom

 

[DW]

If you look in the barrel I bet there is some nice copper streaks in there. I would say you blew the sabot. The same powder charge with a heavier bullet probably stressed the sabot to the breaking point since the heavier bullet should increase the pressure.
Even if you waited the same amount of time between shots, the temp inside the barrel was probably getting progressively higher as the shot count rose, especially in that kind of heat.
The 285 might still be your bullet. Next time out try them first on a cold barrel.

 

[jontom]

DW's resonse

DW, thanks for responding. I checked the sabots. They still had all the pedals, but definitely were stressed. I believe you are probably right about the sabot failure and the extra pressure. I certainly liked how the 1st 285 gr grouped. After posting, I read about some of the Barnes factory sabot were experiencing failure. Thanks again.

jontom