Last night, I needed some plinking loads for today, but didn't have much Varget (reserved for 5.56 service rifle).

I had a pound of H4198 - "too fast" and 3lbs of H4831 - "too slow". I couldn't find data for 4198 and 150gr bullets, and very little for 4831 and 190gr bullets.

What I did find suggested a minimum of 45gr and a max of 50gr with 35k CUP and ~83% burn. Given that there was some data, and a case full of H4831 is less likely to kaboom, I chose it.

I was going to use 48gr, but it was halfway up the neck and probably would've deformed the bullet upon compression to desired depth.


Rifle:
Vz24 Mauser with 22" M1919 barrel chambered in .308 Palma 95 (basically SAAMI min.)

Load:
Hornady 190gr BTSP
46gr H4831 (settles just below neck)
RP case
Winchester LR primer
2.800" (just into lands). Compressed a bit.

Avg velocity: 2223fps
Extreme spread: 66fps
Standard deviation: 19fps

Case necks get rather dirty.

Not an ideal load, but not too shabby.

I'm about to clean the rifle and will update soon^TM with notes, and get pics of the cases.
Hopefully this satisfies anyone's curiosity.


I pulled the last shot left. 9 shots would fit comfortably inside the 1.35" X-ring at 100yds.
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Another 10 shots.
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Cool and interesting.
I've got some Ramshot Big Game I've considered trying with 223 and 77's.
It's wrong in available data, but seems like a similar situation.

For comparison, 40.6gr IMR 4064 was 2520fps, but was about 1.25MOA at best.

The most accurate .308 and 30.06 loads I ever made up/shot in my rifles used Sierra 180 grain match bullets and IMR4350 powder.

Compressed powder charge (it will let you know if a case, or two, has neck tension problems - I've seen the bullets rise right up in the neck while sitting on the bench).
No where near maximum chamber pressure (just can't get that much powder in the case).

If I was someplace where I could shoot long range again I'd be buying a Schuster gas plug for my M1A and working up slow powder heavy bullet loads again.  The 03A4 didn't mind the IMR4350.  I killed the op rod twice in the M1A with those loads (early 80's, pre internet, I had no idea why the op rod was cracking).

Small groups are nice, real nice.

Oh, had a buddy with a Winchester M70 that also loved IMR4350 and 180 grain bullets.  Better groups, by far, than any of the 7 or 8 factory loads he tried or any of the non IMR4350 powder loads we tried.  It was a 30.06, too.

IMR-4350 is a known good powder for heavy bullets in .308. 190 and even 200 grain Sierra Match King's can be driven at useable velocities from bolt actions using this powder.

Winchester commercial brass helps hold the larger powder volumes. 2550+ fps is safely obtainable in 26" bolt actions.

A few years ago I was looking for IMR-4831 data for 174gr RN in a 7.62x54R.

Even in this slightly larger capacity case I found basically what you found and that is there's not enough room inside the casing to over charge it.

But in the end it worked out rather well. I was able to get 2500 fps and accuracy in the M39 is great.  

4831 is just simply a slow burner.

Motor

I used Hoppe's oil last night. Solid black, solid black, white in middle and black in the land/groove lines. It was gonna take a while.

Today I used Hoppe's #9. Solid black, dark gray, gray/green, gray, and that's where I stop when cleaning bores. Rather dirty, but H4831 didn't leave visible soot or cause extra copper fouling.


Front three rows were "The Load" of 13gr Red Dot/150gr bullet. Back two rows were H4831/190gr bullet.

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With such a slow powder and a packed case, it might be worth trying a magnum primer.

Appears to be an abrupt line on the necks where the slow pressure overcame the back pressure, or something like that.

I chambered it with +0.0005" headspace, where it would just close without resistance on a GO gauge. It's the same with other faster powders. Probably from the necks contracting.

ETA: I think IMR 4064 was about as dirty around the necks.