I am loading 338 wm with H4350 powder, Win brass, and WLRM primers. Most books I have show
69 1/2 grains as the max load with the 225 grain bullet. This is the load I ended up with for Hornady
Interlock @ 2690 fps actual. I am now loading the same combination with 225 Grain Nosler Partition's.
I see that the Sierra book show's the same combination with CCI mag primers at a max charge of
H4350 at 75 grains in a compressed load. (I believe the velocity is shown at 2898 fps)
What is the difference in that primer to allow for 5 1/2 more grains of powder in a safe load?
If I work up twards that max with my WLRM primers, how does that different?
I'm not asking to go past max loads, or substitute components, just trying to understand the
process. W/O pressure signs, is there a problem?
My rifle is a Win M70 338 wm with 26" barrel and the BOSS. (24" barrel actual)

Shane, my 22" bbl'd M70 338 WM safely handled 225 Hornadies with 70.5 grains H4350, WLRM's and WW brass at 2,830 ish... I did go 71.0 grains, but elected to run "easy" with 70.5.

A 338 WM with a 24" barrel should easily hit 2,800 (+) fps with 225's... heck, some guys get 2,900 fps and my 338-06 did right at 2,700 fps with 225's!

Brad

Shane: EVERY rifle is an individual, and maximum loads in manuals only apply to the individual rifle in which the testing was done.

Learn to read pressure signs. Alway start below any manual's "maximum". Work up until you are satisfied, carefully watching chronographed velocity, primer indicators, pressure rings, bolt lift, and any other pressure indicator.

Some rifles I own will digest loads well above the average of most manuals, while others reach maximum safe pressures short of even the "mild" loads listed in some manuals. The manual is only a guide, not a bible. Use it accordingly, and compare it with other sources of data before starting.

Good luck!

Shane: EVERY rifle is an individual, and maximum loads in manuals only apply to the individual rifle in which the testing was done.

Learn to read pressure signs. Always start below any manual's "maximum". Work up until you are satisfied, carefully watching chronographed velocity, primer indicators, pressure rings, bolt lift, and any other pressure indicator.

Some rifles I own will digest loads well above the average of most manuals, while others reach maximum safe pressures short of even the "mild" loads listed in some manuals. The manual is only a guide, not a bible. Use it accordingly, and compare it with other sources of data before starting.

Good luck!

I also noticed how much faster a pound of powder disappears with 69 1/2 grains per shell.
Loaded up 100 shells with hornady's for a different load the other night.

StoneCreek is 100% right. I have loaded literally thousands of rounds for 338. My custom rifle with 22" barrel consistently turned in velocities over those listed in the manuals for 24" barrel with book loads. I did find that R-19 and H 4831 gave considerably more velocity than 4350. With your long barrel I wouldn't be suprised if you could get nearly 2800fps with a 250 if you work up carefully.

Thought I'd post the follow-up results to my question for you folks. I was mistaked about the velocity for the 225 grain Hornady's and 69.5 grains of H4350. Chrony read right at 2800 fps which makes more sence. (than 2690 fps posted before)
I did work up a load for the 225 grain Nosler Partitions with win brass, WLRM primers, and H4350 for my 338 wm. Ended up working up to 74 grains. Sticky bolt lift showed up at 73 1/2 grains and 74 grains. I did achieve over 3000 fps with that load. Not a misprint! My chrony read 3013 and 3011 fps with the 225 grain NP's. I backed off to 73 grains and had no pressure signs. Velocity was a consistant 2950 fps out of my rifle. This is more than the books show. Accuracy was 1" to 1 1/2" groups but improved as I played with the boss. I believe I found my load for my CO elk hunt next week. Which is good as I leave one week from today.
Thanks for the help everyone.

Shane, I am loading 65.0 of IMR4350, 250 Nosler Partitions and Hornady Spire Points, Win brass, Fed 215 mag primers. Don't know the velocity, no chronograph available and I need to get a load that shoots well (this one does, into an inch at 100 meters) for moose hunting in Quebec, leaving later this week. Will chrono this and work on the load over the winter.

How are things down Rio way? I used to hunt a lot at Grand Marsh and French's Creek back in the 70s when I lived in Madison. Deer hunting in Adams County. Some great times. -Fred

Fred,
Not to many people have ever heard of Rio (population 800). I've lived and hunted here all my life. I have good deer and turkey hunting on my land as well as friends private lands. Took my first deer with a bow on public land, though. This will be my 4th trip to CO. All I need is an elk in my sights.

70 gr of 4350 with 225 gr bullets has long been a favorite load of mine.

It also works well with 210 Barnes XBT's.