I loaded up some 200 gr speer bullets with 105 grs of reloader 25 podwer.They kicked less than my 243 with the break ojn the 338-378.I am looking for a deer load .I will have to check it out to 300 yards.I am also going to try some 300 gr Lapua Sentar bullets with a 50 bmg powder that is supose to get 3000 fps out of a 26" barrel. we will see.I know those will kick .I tried 300 gr Serria Match kings at 2850 they have some push back.I am going to try some other bullets such as the nosler 225 gr accubond bullets.I usually use 250 gr nosler partitions in this round but they are too tough for deer .They would work good on black bears but it will be a deer black bear combo.I love this cartridge and the gun the Weatherby 338-378 Accumark.I snached it up at an awesome price.This is my third one of these.Anyone have any 338-378 deer and bb loads?I will be shooting under 300 yards for both of these.

Do you have anything against venison?

That's one hell of a Deer round, especially for 300 yards and under.

That's one hell of a round for anything living. I enjoy it when the macho's at the range ask me to let them shoot a round. Most of them have a respect for the round after firing.

My load for my 338/378 weatherby is 110gr of RL25 with 250gr Swift A-Frames. These chronoed a little over 3100fps and would group about 1.25" at 200yds fairly routinely. I used it in Alaska for my brown bear in 2001. My guide asked that I bring something that could reach out and touch one if needed. I had planned to take my 416RM. I ended up shooting my bear (squared at 9'2") at seven yards in a thicket.

You're going to be hard pressed to get 3000 fps. with the 300's out of the stock barrel. 2700-2800 is probably more realistic.

I had great luck with 200 gr. Ballistic Tips with 104 gr. of RL-25 back before they discontinued them. I used the BT's for cheap target loads because they were super accurate and dirt cheap. I shot a few deer with them too, in a pinch, and they worked fine. No drama.

I've got loads for bullets all over the map, but for hunting since it's usually around Texas I typically run bullets on the light side for 338. 210's and 225's. Lately, I've been shooting a lot of the Hornady 285 gr. Match bullets with 96 gr. of RL-25. Out of my 29" bbl they're running about 2900 fps. and shoot about 3/4" @ 200 yards. For my hunting load I've currently got 210 Barnes TTSX's loaded, also with Reloader 25. RL-25 is my go-to powder for just about everything. It's the first thing I try whenever I'm trying a new bullet. Beyond that, I will generally try H-1000, IMR-7828, and H-Retumbo. Retumbo can be hit or miss. Sometimes I get phenomenal accuracy out of it, but unfortunately it can also be touchy. I've had squat for luck with 50BMG in 2 338/378's and 3 different barrels. In my opinion, skip it.

Congrats on your new find. Hope some of the info above gives you a place to start. Best of luck with it!