Some more BPI seal and sabot testing.
First of all both Bret and I have heavy tight fit barrels
and his barrel on the Savage is faster twist so it took
him 50 gr of Longshot to get what BPI got with
looser barrels and slow twist at 46 gr of Longshot.
For non heavy barreled guns only go to 46 gr.
I did a bunch of tests in my NEF long barrel with long
chamber. My store didn't have any 500gr .500" XTP slugs
so I used some 420gr .512" dia lead Great plains in the
BPI sabot. Using 2 BPGS powder seals, a BPI Flexseal, a
cork wad in 3.5" new Federal cases, roll crimped, I got
2800 fps with 420gr slug. I tried 4 other powder seals,
2 cards, a Remington, a Win, and a odd one, all with the
Flexseal and lost velocity. I fixed up my crimper so it would
roll the plastic down and over inside edge of sabot, as before
it would turn plastiC in too sharp and get some of the crimp
outside the sabot top. If sabot was too low so that the plastic
crimp went clear down to the slug I got high pressure signs.
I also did same loads in used 3.5" REM cases ok.
Now, I thought I should have more velocity, so I swaged the
.512" 420GR slug down to .500" like they say the sabot is for,
AND I GOT OVER A 120 FPS MORE. Everytime. I also used
Alliant Steel powder and got all the same results, using
60gr. It is easier on cases. I also substituted the doubled up
BPGS powder seals and the Flexseal with 520gr Lyman in
place of the seal and cushion on the WW12 wadcup the Lyman
fits in, with some RL-17 loads, of 150gr, and got over 200fps more
that the original WW12 wadcup gave with the Lyman.
Velocity secret is to have the perfect sealing setup with
slug/sabot combo that is NOT too tight. Only tight enough
to get accuracy. The cork seems to protect the sabot
base ok on the shotgun powder loads, and not needed
on the RL-17 loads, which is a easier accelerating powder
and without cork helps make room for the RE-17. I think I
will get increases in the brass RMC cases, with RE-17, with
the BPGS doubled and a Flexseal in place of cards and wads.
We will know soon.Ed