DJ,

My Dad has a 338/300 WSM and maybe I can answer some of your questions. I've tested some ammo on the Oehler M43 and PressureTrace and can tell you it will duplicate 338 WM MV, even shooting the 300gr SMK. There is a fly in the ointment with his though. It was throated to shoot the 300gr SMK and we run pressure up to 63-67,000 psi as well. His has a 25" barrel at present, was 27.5 and lost about 50-75 fps depending on the load and powder used. He uses the recalled RCBS dies without a hitch, but they are not against the shellholder, as you'd expect from the previous comments.

I wasn't testing with him last time out, but he came back with the only group he fired with the 225gr Accubond at 300 yards, 3 shots in under 1/2", one ragged hole basically. His is a 10 twist 3 groove Pac-Nor SM bbl.

The way I see it, it's a dead ringer for the 338 WM, just shorter. 338 WM load data is about dead nuts on.

I'm a big fan of 33's. I hope they come out with it soon......DJ

Brent~
At what velocity was that last outing with the Accubonds?

My own experience with several 338 Win Mags, and two 338/300 WSM's is that the WSM falls about 100fps below the Win Mag in every bullet weight except the 250 and up. At the 250's the WSM falls waaaaay short of the Win Mag, principally because the bullet intrudes so much into the powder chamber.

1: if they use off the shelf stuff, it should be made with 7wsm, as more case capacity is exactly that... don't matter if it's just 2 grains.

2: Boy i would love to see this as a 2.5" case....

jeffe

Bob, you beat me to it. Good as it may be, the 338 WSM cannot equal the 338 WM any more than the 300 WSM can equal the 300 WM... case capacity counts for something.

Is 27-2800 fps possible with a 210 partition in a 338 WSM. Although a bit slower than a 338win I think this performance level is useful. I got this with factory ammo in a Weatherby 338-06 ultra-light but the factory ammo literally had primers falling out of fired rounds! I think a 338 WSM could do 2800 without too much pressure, am I close?...........DJ

The 225's I believe he had over 3000 fps, which didn't surprise me all that much. Loaded with the 225gr Accubond, there's about 3/16" of bearing surface in the cases neck. That should give you and idea of how long his is throated, possibly longer than the ones you guys have loaded for.

I've got some data I'll post on it tomarrow.

The 300gr was smokin right along before he cut the barrel down, still going 2350, maybe 2400 with the right powder.

Bob,
Like I had said previously, he was out shooting himself the last time, and that's the first time he shot the Accubond. He did have his Alpha Chrony set up, but he said tonight that it wasn't picking up shots, giving errors etc, so he gave up on it. It's an unreliable POS, that's why he has me run them over the Oehlers every chance he gets.

He shot some other 225gr before when we had my 35P set up, that's when that 225 went over 3000 fps I believe. I'll get the exact numbers from him, he has the print ream from those tests in his notebook. I never had the M43 hooked up to it then, so that data's not on my computer like this other is.

He hasn't shot the 210's, just too low of BC and too much wind drift. I'd bet the 210 out of his rifle would hit 3100 if the 225 goes 3000. He's got 11 firings on all his brass right now too, Win brass.

The WSM in two rifles, both 21" barrels, gives right at 2900 fps with the 210's. The 225's top out at about 2840 fps. The 250's barely exceed 2600 fps. 185 Barnes hit 3000.

Brent, I'll be real curious about the Accubonds. I'm breaking in a brand new 338/300 WSM on the MRC action today but I'm using and developing loads for the 210's first. The Accubonds come later. I got 3000 fps from the Accubonds out of a 338 Win Mag that normally tops out at 2920 with 225's. Accuracy was poor, no pressure signs and when I dropped down to 2855 fps it printed half inch groups. I don't have pressure equipment, but in spite of the 'no pressure' at 3000 fps and no brass damage, I think your pressure has to be way too high.

Bob,

I was wrong. I appologize. The damn thing wasn't even the 338 WSM, but rather his identical rifle in 6.5 WSM with the 140 SMK at 3070 with 64gr H1000. The other two loads on his printout were 250gr Scenar at 2701 - 2758 with 72.8gr H4831, and the other was the 300gr SMK at 2375 - 2391 with 65.0 H4831. He said he could go another 2-3gr with the 300gr still.

Here's some screen shots of 4 tests. The first two were done in August '03 with the bbl at 27.5", the last two were with bbl cut back to 25" in March '04.

We'll check the 225 Accubond next, he's got 'em loaded so probably this weekend.


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Thanks for the neat post. Would you mind explaining the units under the estimate pressure column?

PEAK = peak pressure. They just drop the last two digits is all. 656 = 65,000 psi.

Here's some info from PressureTraces documentation on the other two -

Area (Area Under the Curve)

The area under the curve is calculated using the velocity information for each shot, the effective barrel length and the pressure curve.� This is an indication of the actual work performed, by the expanding powder, to force the bullet from the muzzle.� A large value for Area Under the Curve is preferable to a large peak pressure to attain the same velocity.

Rise (Rise Time)

The rise time is calculated as the time, in microseconds, it takes for the pressure to rise from 25% of the peak value to 75% of the peak value.� This can be taken as an indication of the "speed" of the powder in use.��


Now, I'm not sure if Oehler calculates it from the 25% to 75% or %10 to 90% or what, it is however relative within this test equipment though. Maybe it says in Oehlers documentation.