338-378 wby reload recipes

[flitemedic13]

Hey guys,
Just got in my new 338-378...going to be tossing 300gr accubonds in this gun and need some help before my montana elk/bear hunt. Reload data is skimpy when it comes to 300gr bullets in that caliber and especially with the powders i have on hand. I have retumbo, RL33, RL50 and H50bmg. So far ive managed to find some stuff online and have loaded up retumbo and RL33 (ill post gr weights in a bit when i get back to the house). Id assume the 50 powders have close to the same burn rate but havent found any data on using either. Alliant was zero help when i emailed them for recipes. I cant find any US870 or AA8700 which may be in the middle of the retumbo/RL33 and the 50s...cant find the VV powders that probably would be good in filing that gap either. Anyone have any experience with this cal and load. Ill chrony them at the range this week. My usual reloading was done with 300 RUM where retumbo was a great powder but thinking i need a slightly slower burn for the bigger cal and heavier bullet. Thanks in advance, Jonathan.

 

[flitemedic13]

Also which is slower burn RL50 or H50bmg ?

 

[Dusty Stevens]

Man for a minute there i was afraid you wasnt going to have enough gun!

 

[flitemedic13]

retumbo is loaded at 102,104,105,106 and RL33 is at 106,107,107.5,108 so far.

 

[Dusty Stevens]

RL33 or H1000 would be my first choices then retumbo if it is more readily available. Think of retumbo for something like a 375h&h with a 250gr bullet or comparable. I tried it in a 338lm and it was ok but just not right like rl33 or h1000 was

 

[Drop Port]

retumbo is loaded at 102,104,105,106 and RL33 is at 106,107,107.5,108 so far.

Retumbo works well but can spike quickly. I would research it a little more, some of your numbers are high.

 

[flitemedic13]

Retumbo works well but can spike quickly. I would research it a little more, some of your numbers are high.

I pulled the reumbo #s of loaddata.com but yea they are on the higher side than noslers site

 

[Drop Port]

I pulled the reumbo #s of loaddata.com but yea they are on the higher side than noslers site

The data problem you can run into is that cartridge was / is still popular in the PA area for long range hunting and in the past the 300 SMK and now Bergers are very commonly used. I could be wrong but I believe the Accubond longer surface will cause pressure sooner, combined with OAL, FB, mag fed etc. max loads will vary considerably.

 

[wboggs]

Used to used H870 with 300 gr NP in a custom rifle in the 70's. None of the newer powders were available then. H870 was dirty but that isn't that important in a hunting load
Bill

 

[JRS]

Powder Valley has the VV powders. N170 or N570 would work quite well in that cartridge. In fact, Berger has loading data for the 300 grain bullets using the VV powders, along with others.