Powder Comparison Results in 338 Win Mag

sep

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I've been doing some load development these past few weeks with two of my 338 Win Mags and working up a load for a co-worker's 338 Win Mag. In the past, I have had excellent accuracy with the following load in four 338 Win Mags. 225 grain Barnes X/TTSX bullets fueled by 67.5 grains IMR 4350, Winchester cases and CCI 250 or Federal 215M primers. Ironically, the best seating depth in three of these 338s turned out to be the same. I can't recall the seating depth on the fourth one and I sold it several years ago. At any rate, I wanted to try H4350 (because my three 30-06s love it with a 168 TTSX) and the new IMR 4451 to see how they worked.

The rifles I used were a Browning XBolt with 26 inch barrel and a Weatherby Vanguard with a 24 inch barrel. Here's how the velocity stacked between the three powders using Norma cases instead of Winchester and Fed 215M primers: (I had to increase the IMR 4350 charge weight one full grain to get comparable velocities when switching from Winchester to Norma cases)

68.5 grains IMR 4350 average velocity
XBolt 2825 fps
Vanguard 2764 fps

66.5 grains H4350 average velocity
XBolt 2808 fps
Vanguard 2744

68.5 grains IMR 4451 average velocity
XBolt 2786 fps
Vanguard 2739 fps

So, it would appear the new IMR 4451 is slower than IMR 4350 and definitely slower than H4350. H4350 didn't produce decent groups in either rifle but IMR 4451 did in both rifles. I loaded a few rounds up to 69.0 grains using IMR 4451 and didn't see any pressure signs in either rifle. I may bump the charge weight up and shoot a few more til I see pressure signs then back off accordingly.

I emailed Barnes to see if they had any load data for IMR 4451 for the 338 Win Mag and Ty responded saying they don't right now but they are working on a new reloading manual. He suggested I use Hodgdon's load data from their web site as a rough baseline.

IMR 4350 has been very good to me over the years but I'm gonna see what I can get out of this new IMR 4451. Allegedly it's a little more temperature stable than IMR 4350. We'll see...
 

Longbow6360

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Good info. Thanks for posting your work. It's hard to beat "the old brown mule" IMR4350. I'm flying into town next week so maybe I'll find some IMR4451 and see how it works in one of my 300WSMs.
 

.338 mag.

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Thanks for sharing the info. I have used Reloader 19 for 250 grain loads in my .338 for many years and still have a bunch of the powder and components of the same lot number for my load.

I use a .338 or a 30-06 for all my Alaskan hunting and H4350sc and Reloader 19 will serve me for the rest of my hunting life. That in no way means there are not other good choices available.

Working up a hunting load can be time consuming and I no longer have the fire in my belly to spend hours a the loading bench.
 

L. G.

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Never thought IMR-4350 was 2.0 grs slower than H-4350. They're right next to each other on the burn rate charts.
 

sep

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Never thought IMR-4350 was 2.0 grs slower than H-4350. They're right next to each other on the burn rate charts.

I didn't think they would be either but that's what my Labradar chronograph reflected and that's what Hodgdon's own load data from their web site indicated too. Here's the data from their reloading center using 225 grain Hornadys:


H4350-69.5 grains-2785 fps
IMR 4451-69.4 grains-2777 fps
IMR 4350-72.0 grains-2832 fps

That's a big difference in powder charge weight for an additional 47 fps with IMR 4350. I initially thought I had a fast lot of H4350 til I chronographed two of my 30-06s using the max charge weight of 55.5 grains of H4350 fueling the 168 TTSX.

Barnes' manual states an expected velocity of 2825 fps with this charge weight using a 24 inch barrel. My XBolt with its 22 inch barrel clocked in at 2832 fps and my Remington 700 with its 24 inch barrel registered 2813 fps. So, it would seem my lot of H4350 is at least in the same ballpark as Barnes' data.

The new Hodgdon powder burn rate chart now shows IMR 4350, followed by IMR 4451 and then H4350. The velocities I've been getting and seeing on Hodgdon's web site don't seem to agree with that burn rate. Assuming, the slower the burn rate, the more powder needed to achieve a specific velocity. It looks like IMR 4451 is the fastest of those three powders in terms of powder charge weight and maximum pressure but not velocity. It does shoot accurately in both my 338 Win Mags and I'm waiting to see what data Barnes publishes for IMR 4451. Until then, the old brown mule (as Longbow6360 so eloquently put it) will continue to carry my water.
 

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