We are in the middle of having our floors redone in our house and my computer is packed up with all my Quickload notes and out of commission for 2 weeks. I need to order powder for a project I am finishing up and need to see if someone can run a powder query for me in QL. Any help would be appreciated.

375 RUM, 350gr. Barnes TSX, COAL 3.580”, 24” barrel

From memory N560, MRP, 7828SSC, RL22, and H4831 were up there but don’t want to guess.

Since H4350 works so well in every .375 I use it in with 300-grainers, (.375 Wby, .375 RUM, .375/404 JS of 2012, .375 Twister),
I would probably use it with the 350-grain TSX.
H4350 has 100% burn, 97% fill, and 6 fps faster than H4831SC (compressed, 103% fill, 99.1% burn) at same max pressure.
Both are "Extreme" powders with good TBI.

BTW, my pet peeve is use of COAL instead of COL for Cartridge Overall Length. Bob Mitchell agrees with me.

From my old version, most of the powders are still good, at least they match my stock of pre-2016 powders (AA-2230 was updated in 2016,
not applicable here):





I would use same data in all three of these:
.375 RUM factory M700 LSS
.375/404 Jeffery Saeed of 2012 (has CIP .375 Weatherby Throat) CZ 550 Magnum custom
.375 Twister (.375/.338 Lapua Magnum) CZ 550 Magnum custom.

Actual case capacity for those three is in the 120-121 grains of water range.
The QuickLOAD default case capacity that popped up was 117.0 grains water for the .375 RUM.
I went with that to be conservative.

That bullet length was looked up on the 'puter, 1.691" for the 350-gr TSX, 5 cannelures like on the .458/500-gr TSX.

Rip ...

Yep...I was between H4350 and H4831SC...I like those powders because they are extremely consistent across temperatures and relatively easy to find. Have an 8lb tub of H4831SC sitting around for my 6.5-284...might try a bit along with H4350 and see where it gets me. Appreciate the help RIP.

The MRP, IMR7828 SSC, RL 22 loads are interesting but the temp variation in those powders isn’t something worth chasing a few extra FPS.

N560 is very intriguing as I find it to be very consistent...but it is about as rare as unicorn farts and I don’t want to do load development and then have to wait on more powder. I run N570 in some other rifles and have enough squirreled away for that but it was on backorder for over a year.

Overall, a 350TSX cruising along at 2500fps will have a trajectory similar to or better than an H&H with 300gr and more energy, albeit at a price of recoil but no free lunches.

JMJ888,

My pleasure, I will file that in the .375 RUM Oxford binder.
The .375/350-grain TSX is an interesting bullet.
With all that sectional density (0.356) it is bound to expand well at anything from 1600 fps to 2600 fps impact, yet drive deep.
The G1 BC is pretty good too, with all that length (0.425).
Ought to be an all-range big-game-killer for sure.

One of my .375/404 JS-2012 barrels for a CZ 550 Magnum has a 1:10" twist, all others are 1:12".
I am going to check the McGowen twist calculator for a 1.691"-long copper bullet.
IIRC, 1:12" twist is good for the .375/350-grain TSX, but at what minimum muzzle velocity?

Edit: McGowen Twist Rate Calculator
2500 fps MV: 1:13" or faster twist required, 1:12" is faster, is good
2100 fps MV: 1:12" or faster twist required, 1:10" twist is faster, and would be good down to 1600 fps MV for the recoil sensitive.
(Keeping MV above 2100 fps should be no problem with a 1:12" twist .375 RUM.)

Who knows, what will actually be better in one's .375 RUM?
The rifle must decide between H4350 and H4831SC.

Rip ...

I figured I was more than ok with 12” twist. Should be covered on everything from varmints to pachyderms. If I want to do it with nostalgia I will get the H&H out of the safe.

Will get lots of work on our pesky pigs around here and may take it out for spike elk this fall for grins. Will report back when I start load development...actually want to wait until it warms up around here so I can work up a load in high temperatures.

Actually found N560 on the shelf at a local store so I bought them out of it and a few pounds of H4350. The N560 was intriguing not because of the high end velocity but for the fact that I have often found accurate loads slightly below max charge which would give me targeted velocity of 2500ish at slightly lower pressure.

Will start load development with N560, H4350, and H4831SC and let the rifle decide.

quote:

Originally posted by RIP:
JMJ888,

My pleasure, I will file that in the .375 RUM Oxford binder.
The .375/350-grain TSX is an interesting bullet.
With all that sectional density (0.356) it is bound to expand well at anything from 1600 fps to 2600 fps impact, yet drive deep.
The G1 BC is pretty good too, with all that length (0.425).
Ought to be an all-range big-game-killer for sure.

One of my .375/404 JS-2012 barrels for a CZ 550 Magnum has a 1:10" twist, all others are 1:12".
I am going to check the McGowen twist calculator for a 1.691"-long copper bullet.
IIRC, 1:12" twist is good for the .375/350-grain TSX, but at what minimum muzzle velocity?

Edit: McGowen Twist Rate Calculator
2500 fps MV: 1:13" or faster twist required, 1:12" is faster, is good
2100 fps MV: 1:12" or faster twist required, 1:10" twist is faster, and would be good down to 1600 fps MV for the recoil sensitive.
(Keeping MV above 2100 fps should be no problem with a 1:12" twist .375 RUM.)

Who knows, what will actually be better in one's .375 RUM?
The rifle must decide between H4350 and H4831SC.

Rip ...

My understanding of twist is that overall forward velocity slows down faster than rotational velocity/spin. that means that when a bullet slows down its rate-of-twist increases. If a bullet rotates once in 10 inches at the muzzle, when the bullet slows down to covering 8" in the same time the rotation is still close to '1', so the "twist" has increased.

Is this incorrect?

The spin of the bullet is pretty constant in RPM's or revolutions per second, slowing down insignificantly throughout the flight.
Was it in Hatcher's notebook where it was observed that bullets fired straight up would come to zero forward velocity and still be spinning at same RPS?
They would then fall base down and still be spinning at same RPS when they reached terminal velocity downward,
still pointing straight up when they hit the sand,
and scattering the sand with their spinning bases.

The dazzling or baffling 416Tanzan would have us believe that the pseudo-twist of the imaginary barrel that fired that bullet that had slowed to a linear-translational stop at maximum altitude
could only be expressed as zero.
1:12" on the ground becomes 1:0" at zenith.
Or does that mean infinite revolutions per second?
Nah.
Revolutions of the bullet per unit of time, not revolutions per units of linear distance traveled by the bullet, is the only thing that makes sense once the bullet has left the barrel.
Gyroscopic stability in the medium of linear translation would be determined by MV and twist resulting in revolutions per second of the bullet.
Not velocity down range, eh?
1:12" twist is fun because RPS = FPS at the muzzle exit.

Rip ...

Me thinks that the sand would splatter from impact, not the spin when the bullet hits earth.

But let's use your hypothethical 12" twist for a bullet at 3000 fps. That is 3000 r/second. If the rotation continues (maybe inside a slight supercavitation bubble in the air?) and the bullet slows its horizontal velocity to 2500 fps (slownees resulta from making that supercavitation bubble plus air resistance), we now have 3000 revs at 2500 fps. Or 6 revs at 5 feet. 5 feet is 60 inches. 6 revs at 60 inches is now a 1 in 10" twist. Bullet has slowed, gyroscopic spin is relatively faster by distance, 1 in 10" twist at 2500fps. Bullet should be more stable (until it enters a new medium or crosses the sound barrier).

PS: bullet would be pointing ever so slightly upwards as it eventually sinks to the ground from its horizontal flight unless its spin corrects the ever so slight yaw from the curvature of flight. At this point my common sense leaves me, and we would need to run some experiments to see what actually happens.

PPS: the bullets main problem would seem to be the first 100 yards when it is overcoming the yaw of its violent barrel exit and "going to sleep" as they say.

Finished up the first phase of load development with the 350gr. Barnes TSX and decided to start with IMR 4350 powder in the 375 RUM. Used new unfired ADG brass with charges of IMR 4350 from 80-85gr in 1/2 gr increments lit off with Federal 215 GM primers...same data in Barnes manual. Outside air temperature ranged from 98-101 degrees. All velocity was recorded with a LabRadar chrono...3 shot groups fired at 100 yds. OAL at 3.595” putting the TSX 0.030” off the rifling and functioning out of magazine.

Velocity ranged from an average of 2425fps at 80.0g and peaked out at an average of 2586fps at 85.0g. I found a lower accuracy node at 80.5 and 81.0gr that were both sub 1”. The two that stood out were 83.5 and 84.0 loads by far.

83.5g - 2529, 2529, 2529 - ES 0, SD 0, 0.540” group
84.0g - 2557, 2541, 2559 - ES 18, SD 8, 0.760” group

Was going to try a few other powders but don’t see much reason to at this point. 1/2”-3/4” accuracy capable big bore with a ton of SD, trajectory matching the H&H/300gr combo, and the energy approaching or matching a 416 Rem/Rigby.

Will load up some rounds to confirm loads and hunt a few pigs around here, and then likely try some wet newsprint penetration tests to see how the longer TSX performs. Should be a devastating combo.

quote:

and the energy approaching or matching a 416 Rigby.

I would just be content with whatever the 375 does and not compare to 416Rigby.

All of our Rigbys do around 2825fps with 350grain TTSX, which is around 6200 ft-pounds, zero pressure signs. You don't even want to think about that in a 375H&H.

quote:

Originally posted by JMJ888:
Finished up the first phase of load development with the 350gr. Barnes TSX and decided to start with IMR 4350 powder in the 375 RUM. Used new unfired ADG brass with charges of IMR 4350 from 80-85gr in 1/2 gr increments lit off with Federal 215 GM primers...same data in Barnes manual. Outside air temperature ranged from 98-101 degrees. All velocity was recorded with a LabRadar chrono...3 shot groups fired at 100 yds. OAL at 3.595” putting the TSX 0.030” off the rifling and functioning out of magazine.

Velocity ranged from an average of 2425fps at 80.0g and peaked out at an average of 2586fps at 85.0g. I found a lower accuracy node at 80.5 and 81.0gr that were both sub 1”. The two that stood out were 83.5 and 84.0 loads by far.

83.5g - 2529, 2529, 2529 - ES 0, SD 0, 0.540” group
84.0g - 2557, 2541, 2559 - ES 18, SD 8, 0.760” group

Was going to try a few other powders but don’t see much reason to at this point. 1/2”-3/4” accuracy capable big bore with a ton of SD, trajectory matching the H&H/300gr combo, and the energy approaching or matching a 416 Rem/Rigby.

Will load up some rounds to confirm loads and hunt a few pigs around here, and then likely try some wet newsprint penetration tests to see how the longer TSX performs. Should be a devastating combo.

That sounds rational.
In 2003-2004 when I tried the 350-grain Barnes Original in the .375 Wby with 24" barrel,
average temperature 50*F, and +12 fps correction for 5-yard chrono to MV, for BC = 0.370:

My maximum loads in a smaller case capacity with pressure let-off
by shorter bullet length and CIP .375 Wby throat:

IMR-4350: 84.0 grains >>> 2514 fps MV

H4831SC: 89.0 grains >>> 2466 fps MV

Norma MRP: 90.0 grains >>> 2575 fps MV

Oh yeah: I like that load of yours with 0 fps st. dev. and tight group on target.
That is some fine wine right there.

Rip ...

Thanks for the info on the 375 WBY RIP...nice to know we are in the same ballpark. The 80.5 and 83.5g loads both corresponded to flat spots on the velocity curve as I worked up and I can see the groups close in significantly at those points.

First two shots at 83.5 hit the same hole and 3rd opened it up a little. I actually thought my chrono froze up when it registered same velocity 3 times in a row.

quote:

Originally posted by 416Tanzan:

quote:

and the energy approaching or matching a 416 Rigby.

I would just be content with whatever the 375 does and not compare to 416Rigby.

All of our Rigbys do around 2825fps with 350grain TTSX, which is around 6200 ft-pounds, zero pressure signs. You don't even want to think about that in a 375H&H.

Referring to the 375 Ultra and not hot rodding the H&H.

I think it is well within reason to make the comparison to the 416 Rem/Rigby “on average”...not your specific Rigby. When looking at manufacturer published load data, velocity ranges from low 2500-2675 with 350gr in 416 Rem/Rigby which I would consider the conservative average. My results above prove I can hit inside that velocity window with that weight bullet and voila “approaching or matching energy of 416”.

The driver for the project was a two rifle African battery to have a plains game rifle that could double as heavy backup for DG if needed. I wanted to match the tried and true ballistics and trajectory of the H&H/300gr combo but utilize greater case capacity to drive higher SD bullets hard should I need it. The limitation is that being a lefty there are few ways to a cost effective magnum action to house cartridges like the Rigby...CZs are out there just not as plentiful as the M70 Classics, which I love and gravitate towards.

The H&H, 375 Ruger, 375 WBY, all would have been excellent as well as any of the 416s...I just chose something a little off the beaten path. The result is that I can push a 375 350gr TSX with an SD of 0.356 and BC of 0.425 as flat or flatter than the H&H with 300gr bullets, and I think I left very little if any on the table when compared to penetration of 416s with 350gr. Covers the entire spectrum of choices fairly well.

Having said all that conventional wisdom says my H&H/Lott will be my likely combo...but a 375RUM/500A2 combo has a nice ring to it.

quote:

Referring to the 375 Ultra and not hot rodding the H&H.

Yes, that's fair.
And when comparing to 416's, I tend to view the 416Ruger and 416Remington together as one level, and leave the cavernous 416Weatherby and 416Rigby as another level.

Of course SAAMI and the handbooks load the Rigby down to Ruger/Rem levels, but that does not do justice to the 130 grain capacity of the Rigby design with modern rifles and modern powders.

BAck in the day when people had to handload their Rigby ammunition, Jack O'Connor found that he could load the 400 grain bullets to 2600 and over without any problem, but he didn't like the recoil. That, too, is a realistic position. If the Lord gives me health and opportunity I expect to move to a 416 Ruger sometime in my 70's. For all-around loads I expect to use 2600fps with the 350 grainers. They will take buffalo nicely and reach out for hartebeests, too. Maybe a slick 300-320 grain Hammer will be available for 2700fps. But the rifle will be a lean 8-pounds bare, and pushing 9.5 # fully loaded and scoped. Nicer to carry in the forest than a 10.5-11 pound CZ Rigby. My 500 AccRel weighs almost as much as the CZ Rigby, too. My son can take that over. Maybe I'll carry the lightweight 338 as a general meat gun. The Tikka is a joy to carry and it can handle itself fairly well should push come to shove. Your 375 Ultra would pretty much split the difference and could be a nice carry, too.

JMJ888,

Excellent rationale for those rational loads.
But hey, the hero of UNINTENDED CONSEQUENCES used a .375 WbyMag and a .500A2.
John Ross has some gun sense.

I have a Remington factory .375 RUM M700LSS with 26" barrel.
It shot Remington factory-loaded 300-grain Swift A-Frames very well, 2803 fps at 5 yards, and 0.52 MOA at 100-yards for 3 shots.
So, I can stick your recipe in my pipe and smoke it too,
substituting H4350 for the IMR-4350, of course, like Saeed uses.

Ought to be great in the .375 RUM, .375/.338 Lapua, and .375/404 Jeffery also,
all peas in the same case-capacity pod (about 1 grain of spread in gross water with my brass checks),
difference in throating is the only real consideration,
and use of longer COL in a +3.8" mag box follows after that.

To load that 350-grain TSX most efficiently in the beloved .375 Weatherby Magnum would require using a +3.8" box length like in a CZ 550 Magnum,
(or a Dakota M76 African like Saeed does with his long-nosed, 300-gr Walterhogs in the .375/404 JS)
seating it out as long as possible.
If one could add an extra 0.200" to COL, it would increase the effective case capacity of the .375 Weatherby by about 5.6 grains of H20.
If using Norma .375 Wby brass that would still be about 4 to 5 grains shy of the .375 RUM in a +3.6" box.
This does suggest that Saeed's use of the +3.8" magazine box (with his .375/404 JS Dakota African)
gives it a 5.6-grain advantage over its use in a merely +3.6" box.
The 300-gr Walterhog nose is so long that he would have to seat some of the ogive below the case mouth in a mere +3.6" box,
so he is stuck with the longer magazine box like he is stuck on the 300-grain Walterhog.

Rip ...

RIP the only Lefty CZ 550 I was able to get my hands is being converted to the 500 A-square by AHR and should be finished any day now. I originally wanted to do a long throated 375 RUM in the 3.8" CZ box for the 350gr TSX but alas there are so few of the true magnum lefty actions that I opted to go big and keep the RUM in a standard 3.6" box M70. The length of the 350 encroaches on the powder column a bit and moving it out would have freed us some space.

I think a long throated 3.8" RUM could play in 378 WBY territory but I am finding over 3.6" would just be diminishing returns on recoil for little benefit. Cant have it all but I think I am happy with the compromise.

Good compromise.

Rip ...