Mark

I'm looking for a load that will drive the 260 Accubonds fast and accurate in the Weatherby case. Any ideas? It would seem that 88gr of H4350 might be the ticket. Comments?

Mark

Mark,
Good load. What velocity are you getting in what barrel length, and what kind of accuracy?

Anyway,
you are not at top velocity or pressure most likely, but if it shoots well, stop there.

88.0 grains of H4350 is the perfect powder charge for just about any 300-grainer in all three of my .375 Wby rifles.
In the CZ I increase the COL from 3.600" to 3.750" and add more powder.

Back when I first developed loads for the 375WBY I was using RL-15 and IMR-4350.
I have since switched to Varget and H4350,
primarily due to better temperature stability.

An excellent load with the 260-grain Nosler Ballistic Tip was:
79.0 grains RL-15
GM215M or F-215 primer (interchangeable)
Hornady basic brass formed into .375 Wby (less capacity than proper Norma .375 Wby brass)
24" barrel
velocity:
2845 fps
I planned on trying 80 grains of Varget
as a replacement for 79 grains of RL-15.
Never got around to it.
Should be a humdinger, about max, with the 260-grain Nosler BT or Accubond.

AA-4350, IMR-4350, and H4350 are pretty much interchangeable in the .375 Wby, depending on lot-to-lot variations, of course.
I usualy go up to 90 grains with a 260 to 270 grain bullet.
88 grains of any of the IMR's with most 300-grain bullets.

Last time I checked,
the velocity result:

H4350 (new lot): fastest
AA-4350 (old lot): medium
IMR-4350 (old lot): slowest

But there was only about a 30 fps spread, all with 88 grains of those three 4350s.

88 grains of H4350 with 300-grain Nosler Partition gives me 2740 fps in my 24" barrel and duplicates Weatherby factory ammo.
Fast as a speeding Walterhog!
I use the Norma-made, proper-headstamped brass for that.
GM215M or F215 primer.

RIP,

One problem I have is the rifle is a custom M70 so I'm limited as far as OAL. You need to keep the length at 3.58" for reliable feeding from the magazine. 85gr H-4350 is absolutely max with 300gr TSX. Yes! I am using a drop tube. Learned that one from trying to put 80gr+ of IMR 435O in a WW 375 H&H case under a 300gr SAF. Old Bob Hagel load. Powder not bullet.

The 79gr R-15 load sounds good as I think that much powder will fit under the Accubond. I'll let you know.

THX

Mark

I have a question about the 88 grains of H4350.
My QuickLoad shows that to be way over max pressure and filling 110% of case capacity. 72304 psi.

So what am I entering wrong into the program? Just wondering?

Rusty,

You are doing something wrong. Check the loads in the Barnes No 3 Manual for 375 Weatherby. They recommend 1-2 grains over max loads for the the TSX which is the closest 375 Weatherby data that I know about for the 260 Accubond.

Mark

That's the very load I use in my Ackley with 260 Ab's Ran the powder up 2.5 grs more but saw no benefit and the 88 gr load shot sub 3/4 inch.

Rusty,
Yep, bad inputs if you are using defaults.
QuickLOAD has the wrong case capacity (105.0) and wrong brass max (2.850").

Actual .375 Weatherby headstamp brass by Norma is 111.5 grains water gross, once fired factory ammo.
Brass length is 2.860".
Bullet factors, starting pressure, etc., blah blah blah.

Mark,
Understand the COL.
I use a 3.565" COL with Nosler 300-grain Partitions because that is where it crimps.
My Pre-64 M70 box is about 3.59".
My M70 Classic box is 3.625"
My CZ 550 Magnum box is 3.840".

I ran some QuickLOAD with the 260-grain Nosler Ballistic Tip data I have, as well as 300-grain Nosler Partition at my various COLs and was pleased with the comparison to reality, and the theoretical safety, of the results.

QuickLOAD ain't always right.
But it says your 88 grains of H4350 is faster than 79 grains of RL-15.

I take it that the measurements of length and boattail base specs of the Ballistic Tip are not the same as the Accubond, but they are of the same weight, 260 grains.

If you want me to do the Accubond,
post the following, all in inches:

1. bullet length
2. smallest diameter of the boattail base
3. length of the taper from base to full diameter (nonrebated boattail)
4. your barrel length

That will give more precise results than the following (for the Ballistic Tip):

24" barrel
3.580" COL
260-grain Nosler Ballistic Tip:


H4350
************
88.0 grains: 101% case filling
2901 fps
58,182 psi
************
89.8 grains: 103% case filling
2958 fps
62,222 psi
************

Next powder:

RL-15
************
79.0 grains: 90% case filling
2811 fps
56,103 psi
************
82.2 grains: 94% case filling
2907 fps
62,829 psi
************

Next powder:

VARGET
*************
80.0 grains: 95% case filling
2818 fps
58,982 psi
*************
81.6 grains: 97% case filling
2865 fps
62,431 psi
*************

I think QuickLOAD has the correct max average pressure listed in the default settings: 4400 bar (CIP) = 63,817 psi Piezo (CIP)

Thanks guys!

I have noticed a pattern of QuickLOAD underestimating the velocities attained with Varget and RL-15,
but overestimating the velocities attained with H4350.
Seems to hold true with the .375 Wby.
This was the first time I had tried QuickLOAD on the .375 Wby.
My comparison is to the loads actually chronographed by me.

Only the shooting of the loads in your rifle will tell which has the best combination of speed and accuracy.
Pressure?
I am stuck with QuickLOAD for that.

With cyber powder lots:
+/- ??% error in pressure

RIP

Thanks! I 'll try the H-4350 and R-15 and tell you what they run at. Friend has an Oehler with a printer so I should have some accurate data in a few days. My barrel is 24" but I think if I built another 375 Weatherby I'd go for 26". Your 375 Weatherby on the CZ may be the optimum for the cartridge with its long magazine. There is no need for the bullets to intrude as far into the case as the TSX does in my M70. This definitely restricts powder capacity and therefore performance.

Mark

RIP

Tried 88-90 gr. H-4350 with the 260 Accubond in the 375 Weatherby. Easily got the 2900 FPS but accuracy was terrible. 270 TSX is next I guess.

Mark

Try the RL-15 before you give up on the Accubond.
To each (rifle) its own.
Different stokes for different blokes.

quote:

Originally posted by RIP:
Try the RL-15 before you give up on the Accubond.
To each (rifle) its own.
Different stokes for different blokes.

Double ditto.

Mark, PM me and I'll share all my 375 Ackley Improved (a.k.a., 375 Weatherby) 260 Accubond data. Regards, AIU

Bump -- gonna try 260-grain accubond with my 250-grain TTSX load (78 grains rl-15). Not happy with IMR 4320 or IMR 4064. Did Mark pick one?

Anyone try Reloader 17? Seems it would be very good, maybe even more so with heavier bullets.

Gonna stick with TTSX's. Oh, well...