I tried serria match king 300 gr bullets years ago .I was wondering if anyone has tried 300 grain 338 accubonds or any others hunting .I usually use 250 gr nosler partitions in my Weatherby accumark I have shot 1 inch groups at 300 yards but wanted a longer range bullet .I am going to try reloader 25 ,h870 and wc867 powder

A friend of mine built a 338-378 a couple years ago, settled on 300gr Berger and RL33. seems to shoot awesome (for a Weatherby )

btw: nothing wrong with 300gr SMK

The only 300 gr I used (in the late 1980s) was the .049" jacket Barnes for a best of 2998 (instrumental at 10 ft.). Most powders didn't give that much, more like 2800-2850.

I shoot the 300 grain SMK in my 1/10 twist Accumark Weatherby and very acurate to 800 yds. I didn't try farther because range limit. 338/378 Bee. i recommend this package, however brass expensive.

I have a NIB HS Precision in 375 RUM at a great price if anyone wants to get in this game.

What twist rate is the RUM using in 375?

I am shooting a 338-416 Rigby Improved. Almost the exact same case capacity as your 338-378. Shooting 300-grin Berger Hybrids or 300 SMKs over RL-33. This provided another 100 fps over my Retumbo loads. Give RL-33 a try!

No experience with the Accubonds yet...

I shoot the 300 gr Accubonds to 3000 fps with Retumbo in my 10 twist 28" Shilen barreled 338-378, run the NF 2.5-10x42 NSX compact with the IHR reticle.

I don't shoot paper [except zeroing] or steel with it, it's just a very hard hitting hunting rifle that's quite manageable at 10.5 lbs all up.