Load Development

[35WhelenAI]

It depends on the bullet honestly. You seem to have primarily 150gr bullets and seem to be leaning toward wanting to shoot those so 760 will be just fine. Win760 is temperature sensitive which is a no-go for me while others say it's a non-issue so to each their own on what they want. SO to avoid my personal preference of avoiding double based ball powder, I'd look for RL16, RL17, RL23, 4831, and H4350

If you were to go to a 180gr or heavier bullet then I'd watch for H1000, Retumbo, IMR7977, IMR8133, RL26, RL23

Did some informal testing years ago when Westchester came out with their WMR magnum rifle powder. Double base, spherical powder. In my 300 Winchester Magnum, I shot ambient temp loads (70 deg) back to back from a cold chamber with rounds I had put in my freezer and kept on ice in a small cooler until I got to the range. Shot the cold loads first, the rounds were just below freezing. 110 fps difference in favor of the ambient temp loads. I would expect similar effect with any Winchester spherical rifle powder. 748 gives great velocity from my 35 Whelen AI with 225 grain anythings, but won't use it in my hunting loads because of the potential for even colder temps in the field.

 

[RockinRam96]

Well good or bad, rang some steel this afternoon with Winchester 760 and 200 grain ELD-Xs at 420 yards.


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[RockinRam96]

Hit the Jack Pot yesterday. On my way back from St Louis I stopped at an outdoor store in Ohio, picked up 3 boxes of Nosler Accubonds, Nosler #9 reloading manual and 8 lbs of IMR 4831.

Bout time to start doing some testing!


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[RockinRam96]

Worked up some loads the other day with 200 grain Accubonds. Shot a nice 1” group at a hundred yards. Best group I’ve ever shot with a bigger caliber rifle. Happy about that.

EDIT: the 4th shot that is high is one that I took compensating for the drop.


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[RockinRam96]

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[RockinRam96]

Working on some more load development. Doing some fine tuning of the powder charge.

Think I have a winner. Shot a 5 shot group that would have been just over 1 MOA at 100 yards. The impact to the left is another powder charge, the 5th shot I took at the center target. But had I aimed at this target, would have impacted right between shots 2 and 3.

I am pretty happy where this is going. I have never been able to shoot a gun much better than 2” at 100 yards. I was a little nervous that this big 300 Win Mag would be even worse with the recoil. Turning out to be much better!

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[35WhelenAI]

Nice, good to see how things are progressing.

 

[RockinRam96]

Hoping to tighten it up a little playing with seating depth and then stretch it out a little once the weather turns.


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[W3 Gunworks]

Use the ladder test let (let me know if you've never heard of it) to figure out the best powder charge of each powder for each bullet that you'd like to use. Then compare a 5 shot group of each bullet with the best powder charge for each that you figured out. Let the rifle pick out the bullet that way.

 

[RockinRam96]

Use the ladder test let (let me know if you've never heard of it) to figure out the best powder charge of each powder for each bullet that you'd like to use. Then compare a 5 shot group of each bullet with the best powder charge for each that you figured out. Let the rifle pick out the bullet that way.

I think I got it. I am preparing this kid for an easter Canada moose hunt this fall. After much consideration, I have settled on Nosler 200 grain Accubond bullets. With the scarcity of powder I settled on IMR 4831.

To find the right powder charge, I looked at
my Nosler book and found the most accurate charge for the IMR 4831, which was 67.0 grains. So I started off with 5 rounds of 67.0 grains, 67.5 gn, 68.0 gn, 69.0 gn, 69.5 gn and 70.0 gn. The 67.5 gn and 68.0 grain loads shot the tightest group.

Next I loaded another batch of 5 shots each of 67.0 gn, 67.6, 67.7, 67.8 and 67.0 grains. The photo I show above was the best group with 67.7 grains of powder.

It was crazy how the groups opened up as I shot different chargers.

Next I need to get and O.A.L. gauge and work on setting the seating depth.


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[RockinRam96]

Picked up a Hornady O.A.L. gauge the other day. Going to try to make myself a modified case this weekend. Drill and tap on the way. I have a few other cartridges that can make modified gauges for in the future.

Question I do have is, is an ogive gauge necessary to have for this process? Does it make things more precise?

I was just going to measure overall case length measured form the lands and work from there. I don’t see where the ogive gauge would make this process more precise. Please indulge.


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[35WhelenAI]

This is probably posted elsewhere, but thought I'd put it out there anyway. Here's a method I have used to get OAL, low tech but works great.

Cut a split in the case neck that extends about 1/3- 1/2 way down the neck in an old case that has been sized. Color the bullet with a black sharpie and start it by hand into the case. "Pinch" the neck around the bullet to hold it firmly and run the dummy round into the chamber and close the bolt. Gently open the bolt and withdraw the dummy round. You should now have an OAL for that bullet.

The bolt closing seats the bullet to touching the lands. The rifling marks show in the sharpie coloring where it touches the bullet, and it's very easy to see if the bullet stayed seated all the way (didn't withdraw slightly) by the sharpie color on the bullet shank. It'll show scrape marks if it started to back out on withdrawal. Repeat a few times to verify a consistent result.

Work backward from there and play with seating depth off the rifling.

 

[Harvey_NW]

Question I do have is, is an ogive gauge necessary to have for this process? Does it make things more precise?

Yes, it will give you a more precise measurement. Bullet OAL and tip formations can vary quite a bit depending on brand, which translates into variance in COAL measurements.