I am using RL15 for those 310's as well. I was only pushing them 2250-2300fps. The slug was found in the 8th milk jug, having cracked the back - I measured it at 4' to the back of that jug.
I also shoot the NOE Thumper in my Whelens. I use WC852 or WC 852f surplus and worked my way up to 55 grains of WC852f. I water dropped them and used 2500+ lube.
Wow, that's screaming! I've only cast one batch of a few hundred, and cast them hard enough for about 2200 mv according to my calculations and experience. I didn't see the need to push them harder than 1950 because the 42 grains shot so well, but I'll throw more R-15 in cases and see what happens. I use a version of homemade lube formula that Glen Fryxell came up using moly grease, beeswax, and carnauba wax. It works very well for high-pressure/high-velocity loads.
Thanks for the info!
