I need to know the maximum safe load for this cartridge:

.338 Win. Mag.
250-grain Game King
Winchester Large Rifle Magnum primer
XX grains of IMR 4350

So far I've loaded 65 through 69 grains.

kk

Contact Sierra Bullets' tech line. They will probably be able to give you the recommended loads for that bullet, but not necessarily with those exact components.

Handloading is an inexact science, and what works in one gun may be dangerous in another gun.

George

It's hard to say for sure. I had one lot of that powder that never maxed out until 70.3gr and my current lot maxed at 69gr. Those were also with a Hornady bullet.

Well, I would say that you are just about there.
You might get away with another grain but that would be about it.

The Sierra manual lists 70.2 grains of IMR 4350 as maximum when using their 250 grain BT bullet.
They list the speed at 2700 fps.

I have shot quite a lot of ammo in a couple of .338 Win Mag rifles while using 70 grains of IMR 4350 and the 250 Sierra. In both my rifles the velocity was near 2770 fps and the accuracy was good. The bullet performance has been good on deer, wild hogs, and elk so far.

The only problem I ever experienced when using the listed load of 70 grains of IMR 4350 was when I tried switching primers. I usually load the CCI 250 with this load, Trying the Fed 215 primer instead lead to MUCH too high pressures.

Oddly enough primers seem to make more difference in a .338 Win Mag than you would expect. Another favorite load of mine for the 250 Sierra BT is 72 grains of RL 19. It gives virtually the same performance as the IMR 4350 load and in one of my guns it is more accurate. It DEFINITELY shoots better groups and gives more consistant performance over the chronograph when using standard rifle primers vs the magnum types. Go figure!

IMR-4350 From 58.6 grains to 72.0 grains
Remington 9-1/2M Primer

R Flowers,
I had the same thing happen with the primers. Loaded up some 250gr and 4350 with CCI LRMag primers. Ran out so I duplicated that load with Winchester standard Large Rifle. First shot the case stuck very tight in the chamber. Ya just never know, EH.

Thanks, everyone for some great information.

R.Flowers:

Give me a description of what I can expect on deer with this load. I'm off to deer camp next week, and the rest of the guys are already talking about holes big enough to eat out of.

I know this is a lot of punch for deer, but I am working on the theory that the 250-grain will hold together. After all. .33 is not effectively different than .308 in terms of diameter.

Of course, it's the energy spent inside that matters, and I've not seen it, so would like your input.

kk

I've shot a some of deer and a few caribou with the 215 and 250 gameking. All were pass thru's without excessive damage. The only bullet I saw recovered was a 250 that a friend shot a brown bear with...it weighted 165 or so grains (can't remember exactly) and had the classic mushroom shape. You should have good performance with these bullets.

The load I use for the 250 is IMR 4350 70.0 grains. Chrono @ 2760 fps.

Good luck with the deer.

Perfect.

kk

kk: As JAB described, both the 250 and 215 Sierra bullets work just fine on deer. I have shot several with each and have never recovered one yet. AND, I certainly have not seen any excessive meat damage in any form.

I remember well a guided deer hunting trip in eastern Wyoming. When I showed up with a Ruger Number One in .338 Win Mag the guide about had a fit. He could not believe I was going to hunt with a single shot and said I would have nothing but hamburger left if I did shoot anything.

He had to eat his words a couple of days later when I dropped a really nice 4 X 5 buck with one shot. The entrance and exit holes (through both shoulders) were about the same size. A 250 Sierra does NOT destroy a bunch of meat on a deer or an elk in my experience.

Go shoot something with that .338 Win Mag and enjoy it. It puts them on the ground!

R F