The VihtaVuori manual lists N140 & N160 for 375H&H. Has anyone experimented with N150 or N550 with 300g bullets? Seems like it would be a nice in-between.

rcasto,

A whole lot of the people who regularly use a 375 in Africa use RL-15. I would start there, as experience beats theory every time.

I have never loaded for a 375, but QuickLoad says that H4350(compressed 4%) or H414 yield best velocity.

The powders you mention, in order of decreasing velocity are N550, N560(compressed 4%), N150, N160(compressed 4%), N540, N140.

Don

N 550 gave me the best performance with 300 gr .375 H&H. 83 gr for 2775 f/s.

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Norbert,

How far up did you have to go from 83 grains to get pressure signs?

QuickLoad predicts 2778 fps at 70,000 PSI for that load -- if the bullet has plenty of jump to the lands. Usually if the velocity is right, the pressure is, too.

Don

I appreciate the input. 83g of N550 seems a little heavy since that charge weight exceeds the max listed of the slower N160.
I know that every rifle is different and reacts differently to pressure, but that still seems high. All I want is about 2500-2550 fps. I can easily get this velocity from my Kimber (24" bbl)with any number of powers but I'm having difficulty reaching it in my Sako Safari (22" bbl). If 2450 is all this rifle will safely give me, I can live with that - but that is why we have fun experimenting!

Thanks again.

You may find that N540 actually does better with the 375. It is quite similar to Re-15.

I've used N550 in a few different cases. In my experience, in cases that have the capacity to use it, it will give higher velocities then RL15, when loaded ~8% heavier then RL15 charges, which produces the same pressure. I haven't tried it in the 375 H&H, but with some careful workup, you just might find it will do what you want. I simply couldn't get enough of it in the 458 lott, but in the .308 and 35 whelen ackley, it has been a very good powder.

Paul H,

Did you find the N550 a bit dirty? I found that even after 2 rounds the throat area felt quite rough and fouled which I was told might be 'ceramicisation' whatever that is. I've found n150 and n160 to be much cleaner.

Quickload is not designed to calculate pressures absolutely from scratch. Only for relative comparision and development of loads if you are starting with known data.
In my Sako no pressure signs.
The N 5xx series of this high energy powders generally give more velocity at lower pressures, in addition you can fill more powder into the case because its higher spec. density.(e.g. Lott). It is a way to "light magnums".( 1000 m with a .308 still hypersonic).
N 540 in the Lott is the only way to achieve 2400 f/s with 500 gr bullets. Barrel 26.5", load light compressed, pressure measured, absolutely safe in hot africa on 20 safaris.

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Norbert,

I was implying no criticism or skepticism with my question about your load. I have personally stuffed embarrassing amounts of N540 into my 416Rem, with absolutely no pressure signs. (I refuse to tell anybody exactly how much. Every time I read my notes I can't believe it myself.)

What got my attention was that in my rifle the velocity was lower than Quickload predicted until I increased the powder load. In yours the velocity was right up there. I'm just trying to get all the data I can, to increase my understanding of how these things REALLY work, rather than blindly trusting books and computer programs.

I place a lot more value on personal reports and experience like yours than on QuickLoad or load books.

The data I get on N540 seems to indicate that it varies quite a bit from lot to lot - a fairly common characteristic.

Don

Don,

If you recall, quickload also predicted extreme pressure in my 458 lott with the RL15 loads I was running, yet, I had absolutely no pressure signs in the gun. I've talked with John Ricks who has used quickload in concert with an M43, and he agrees that with straight cases, the quickload assumptions aren't in the same ballpark, though, it seems with the bottleneck cases, it is very close.

As to N550 being dirty, no, I never had a problem with that.

The only time I had pressure problems with a N550 is when I blindly followed some old and limited data from a handloader article, and had a 20" .308 achieving the same velocity as a 24" -06, N series is good, but has its limitations!

I don't know that N540 is the only way to get 2400 from a 26.5" lott, from my experience, 87 gr RL15 and a 500 hornady ought to be mighty close, but, I will caution my gun had lots of freebore, and loads were worked up in Alaska. I would be curious to see someone do some pressure testing on the combo.

Don't have a load for the powder you listed. I use re 15 at 76 gr for the 270 gr swift in a 21 inch barrel. I get 2750 and no pressure signs. This load exceeds some of the book maximum loads and is the tops with other manuals. I guess the only way to know for sure is to get a M43. good luck. Please post your results, should you survive the hot load test firings. "D"

In the resp. read me file Broemel explicitely says, that Quickloads results are not very accurate for straight walled cases like .458 Win or .22 Hornet. In general he recommends to adjust some powder data to the users experience. My hunting loads are pressure checked by the governmental proof institute Liege.
The closest alternative to N 540 in the Lott is a ball powder PL 512, highly compressed, the case a little bulging, for max. 2300 f/s with 92 gr!

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Paul and Norbert,

I have mentioned the problems with QuickLoad and straight-wall cases many times, that's why I'm so interested in getting as much first-hand data as I can.

Thanks for the help.

Don