Can anyone delineate the process for determining which bullet a rifle will shoot best? My dad has just gotten himself a ZKK 602 in 375 H&H and would like to start working up a load. Actually, one practice load and one general hunting load.

Just grab some bullets and go? Start with 10% below max loads?

Thanks!

Yes,

Start 10% low and work up with each bullet. You will never know which bullet works best until you work up the loads and compare groups.

can you estimate how many shots/groupings that would require?

Do it with 2 bullets as a process of elimination? While we're at it, what powder(s) and bullets have you had success with?

My process is to compare 2 or 3 reloading manuals and then start my loads around the lower third of those recommended. In a case the size of a 375 H&H Magnum, I work up in 1 grain increments until I'm a couple of grains below the maximum recommended loading 3 rounds at each powder charge. When I near the maximum recommended load, I increase the load in 0.5 grain increments. This gives me an idea of accuracy potential and of whether the pressure is OK.

I increase the load until:

1. Accuracy increases and then decreases again or...
2. Signs of excess pressure occur or...
3. I get to around the maximum recommended load and chicken out.

The components I use for 1 to 1.5 inch 100 yard groups are:

1. RL-15 powder.
2. Hornady 300 grain BTSP (1.5 inch groups) or RN solids (1 inch groups).
3. Norma brass.
4. Federal 215M primers.

The 375 H&H Mag. doesn't have much of a shoulder so stretches quite a bit. Expect to have a limited case life because of incipient head separation on multiple reloadings. Run a wire like a paper clip with the end bent 90 degrees down the inside of the fired case; if it catches or you feel a groove, discard that case.

jsl,

grum's advice above on initiating a starting load excellent.

Opinions vary and I do take exception though to expected case life and the supposedly "small" shoulder for a .375 H&H though. grum does though, give an excellent description of how to ensure there are no surpises and inspecting cases fior such a condition.

I find loading for belted cartridges every bit as easy as rimless cartridges. To me it's a matter of matching and adjusting the reloading Dies to the chamber of your rifle after the initial firing.

I've .375 H&H cases that have been fired numerous times and show absolutely no signs of excessive headspace, case stretching or head separations but it's defiantely good to ensure such conditions are not present in your reloaded cartridges.

All great info so far, I'd just like to add a bit though.
When I started loading for my 375 H&H I picked the bullets that I want to shoot in it not a bunch of bullets to see what it liked. I have 300 grain Barnes triple Shocks and 300 grain Nosler Partitions. I did some research on this very forum to see what powder was a common component that typically has shot accurately for a lot of peoples 375's and settled on Reloader 15.
With load development the other guys above have outlined I found a load that my rifle really likes with the Barnes bullets, with 71.5 grains of RL-15 and Federal cases, CCI magnum primers the gun shoots under an inch and sometimes .5" at 100 yards with a 2.5-8 Leupold scope.
Good enough for me.
Now I will see if the same load will shoot the Partition as well.
My suggestion decide what bullet you want to shoot and work up a load to make it shoot. Do some research here on previous posts and there is a wealth of knowledge.

jsl,

Like others have said here, the search function for this forum will probably yield more postings than you need or want to read for re loading the .375.

I searched here and then based on what I read I experimented with TSX, Barnes banded solid, Swift A frame, Nosler and Woodleigh bullets. I tried R-15 and I think 4350 for powders. I found good accuracy with all bullets and powder, and settled with R-15 and Barnes. On paper and game I have found this to be a winning combo.

Thanks, fellas and Happy New Year to all. I'll keep the forum up to date on our findings as we work it out.