375 Whelen Improved

[JeffreyDeGraff]

I got some 300gr PRVI RN to shoot out of my 375 Whelen Improved. Ive been using load data for 9.3x62, because they have almost exactly the same case volume ( I talked about that in another thread). My research has shown Western Big Game powder to be great with heavy bullets in the 9.3x62, so I gave it a whirl with this. I loaded up one round with 64.0gr, one with 64.5gr, and one with 65.0gr, just to look for pressure signs. 64.5 was compressed, 65,0 was very compressed, so I stopped there. I shot them at the range yesterday and had a surprisingly good group.



I need to load some more of these up and see what kind of velocity I’m getting. I’m hoping for 2300-2400fps.


JTD

[JeffreyDeGraff]

Here are my two loads for the 375 whelen improved.


Left is the 300gr PRVI RN over Western Big Game powder. I haven’t shot this load over the chronograph yet, but it is very accurate. On the right is the 270gr Speer SPBT over RL15. This load is going 2515fps.


JTD

[JeffreyDeGraff]

I started load development for my 375 Whelen Improved and the 300gr PRVI RNSP with BigGame powder. Velocity was good accuracy OK, but it would not feed reliably from the magazine. I need a shorter OAL for it to feed, but with BigGame I couldn’t get the bullet any deeper because of how much powder being used (very compressed). So I’ve decided to change direction with a faster burning powder. Winchester Staball Match is between Varget anf W748 on the burn rate chart so I’m going to give it a go. I’ve got 5 rounds loaded up, one of each powder charge going up in .5gr increments, to where I feel like the max charge should be. My velocity goal for this combination is around 2400fps.



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[JeffreyDeGraff]

I was able to go shoot yesterday. With the bullet .030” off the lands, rounds 1,2,3 almost feed and round 4 (the last round) fed perfectly. Next outing I will try .040” off the lands. I didn’t quite get the velocities, with staball match, that I thought I would but I didn’t get any pressure signs either, so I can keep working up. 56.0gr was 2316fps. 56.5gr was 2317fps. 57.0gr was 2314fps. 57.5gr was 2329fps. And 58.0gr was 2356fps. Next time out I’m going to try 58.5 through 60.0gr and see what happens.




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[Flyeralan]

That is one sweet looking rifle!

[JeffreyDeGraff]

After this weekend I’ll let you know if it’s sweet or not. Ha! Just kidding. It’s been a great rifle so far. Hoping to get the 300gr PRVI RN feeding and load developed. Then I can move on to the next bullet.


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[JeffreyDeGraff]

I can’t get the rifle to feed those pesky RN bullets reliably, but the last round in the magazine feeds like glass every time. My plan, if I ever hunt with this bullet, is to just load 2 rounds in the magazine, I can get the first one in easy enough without any pressure on me to do so, and the second round would be fine for a follow up shot since It’ll
feed fine. Honestly though, I’m a lefty shooting a right handed rifle, my chances of a follow up shot are slim to none.


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[JeffreyDeGraff]

Finally got some results with that 300gr PRVI RN. With big game powder I was able to get 2470fps with sub MOA accuracy. With Winchester Staball Match I got 2370fps with just over 1” vertical group, so I’m going to try to add a little powder to tame the vertical dispersion. I’m glad to be making some headway with this bullet.

BigGame


Staball Match


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