Sendero558:
Never used any factory fodder with the 30-378 as I acquired brass before scoring the rifle.
Been using a 30-378 for about 20 years going with Nosler Combined Technology slugs and some partitions all at 180 grains with the barrel and bullets treated with moly. Load has been 119 gr of H870 (no longer made) with the slugs leaving at 3,384 fps from an Accumark. Early on I was doing 120 grains of powder but started getting some heavy bolt lift and about another 100 fps of velocity if one was out in warmish weather. Backed it down a grain, and bolt lift, primer pockets, etc all seem fine.
It's accounted for moose, caribou, and elk with shots from about 50 out to 350 yds. I think this is too much speed for even the Nosler slugs, as I'm yet to recover any bullet remnants or jackets. With the last three elk, I've done behind the shoulder shots hitting a rib on the way in, and during breakdown, have found no evidence of a slug ever making it to the offside body wall. I.e. entrance but no exits and lots of apple sauce internally.
Got exits on caribou, but again nothing recovered on elk or moose. No animals have complained, so I'm still employing the same prescription as I'm happy with and really like the accuracy.
Given the velocities possible with lighter slugs, my inclination is to avoid them, but i have not tried any of the mono brands.
If one ever has the misfortune of doing a solid shoulder or ham shot, he might experience some spectacular meat damage.
On another Weatherby (257) that I run quite hot (like 3,700 fps with 100 grain slugs) I had a quartering away pronghorn take a step forward and down just as I cleaned up the slack. Absolutely ruined the onside loin from the hip pointer up through the on-side shoulder.
I do like speed, but the impacts are a bit explosive. Likely, the heavier slugs would hold up well ballistically for long range pokes and with their greater bulk would probably give one some pass throughs. Factory rounds I've used in some other Weatherby cartridges have typically been hot stuff.
Have a good one,
Last edited by 1minute; 02/02/22.