Many years ago I bought some non-cannister WC-872 powder from pats reloading. I have around 16 lbs of the stuff and had always planned on using it in 300 Win Mag. It has proved too slow for 168 grain and 180 grain bullets. I held out hope for heavier bullets.
A few years later I picked up 1000 30 cal 240 grain Sierra Matchking seconds. 240 grain bullets generally need a 1:9 twist to stabilize and I have a 1:10, but some guys reported success so I figured I would test.
In general the consensus was that WC872 is slow enough that you can't make an over-pressure load. Kinda like 2400 in 10mm; enough powder to be dangerous and you can't seat a bullet.
To that end I determined the max compressed charge I could fit in a 300 win mag and then reduced about 5% for a starting load. My work up was 80.5, 81.5, 82.5 and 83. I also determined that 2750 fps was the max velocity. Referencing similar powders (H870, Retumbo, US869) I expected my 80.5 grain load to produce about 2400 fps, and I hoped that my max charge of 83 grains would get to 2650-2700 fps, but wasn't confident. I loaded those in 2017.
I finally got to test them last Saturday.
First shot of 80.5 grains went 2746 fps. Shots two and three were a bit slower, and then shot four spiked to 2796 fps, and had a sticky bolt and hard extraction. I didn't shoot the fifth shot. Despite the one shot blowing the SD/ES, I had a 0.5" three shot group and a 1.5" total group at 100 yards. Most significantly none of the bullets showed any evidence of keyholing or instability.
I spent Sunday evening unloading the rest of this ammo wth my RCBS kinetic puller, and then loaded up a new test batch starting at 75 grains with a max load of 79.5. I hope to test them one night this week.
While I was a little bummed about pulling ammo, I am very excited to have a bullet/powder combo that will be near max with my powder. I am also now hopeful that I can find a load for my 260 Remington with this powder with some very heavy 6.5 projectiles.
Hey Mitch if you don't mind could you take a picture of the WC872 powder in a scale pan close up.
I'd like to add it to my powder picture files...
Will do. It will be later tomorrow or Sunday as I am away from home at the moment.
I actually have about 4-5 non-cannister powders. I will get pics of all of them for you.