I have had some problems using the 300gr Northfork getting the velocity I wanted using W760 in my .375HH. I was adding alot of powder and getting very minimal gain in velocity, like 30fps. I contacted Mike Brady and here is what he told me.

The slip of paper with each box says, when comparing to the loads given in some manuals, "on average" my bullets require 3 to 4% less powder to generate those same velocities and pressures. That is, what it says it is, an average. I have seen numbers both above and below that average. Obviously it depends on all the normal variables but I have also seen a powder and bullet combination react differently from how the same bullet reacts with a different powder, even in the same rifle. In other words, the same bullet can be "under book" with one powder and "over book" with another powder, even in the same rifle. It is not common but it does happen often enough to know it is not a fluke.

For instance, my 375 barrel uses less RE15 than I have seen quoted by some others, to achieve similar velocities (and pressures). No problem because it achieves the velocities that it is supposed to achieve at the pressures that it is supposed to do it at. I did not have any WW 760 in stock because, in the past, I had found it finicky and I had always found a better substitute, that made it not worth fiddling with. I was curious as to your situation so I went out and got a pound to test.

WW virgin brass, Fed 215 primer, OAL 3.59", 26" barrel

With your 23" barrel, you will be ~80fps behind me.

Basically, I was finding the same thing you were. Velocities and pressures were lower than expected. I started at 74 grains and went up in 2 grain increments. You are also correct that increasing the load does not increase velocity very much. It also doesn't increase the pressure very much either. It also is somewhat velocity erratic at the lower powder charges. Now I didn't have the time (or gelatin) for a large volume of shots per charge but I only got a 35fps increase from 74 to 78 grains and I actually had a 1000psi decrease in pressure????. Actually, it was the higher charge that was the consistent, repeatable one and the lower one was the fluke. From there on up, things started to make more sense. I stopped at 80 grains as that was a 101% load (with virgin brass), even with a drop tube. I do not and will not compress ball powders, nor do I recommend doing so, especially when traveling to Africa. At the 80 grain charge, I was 2627fps and I was still 6000+psi below the pressure generated by RE15 to achieve 2580fps.

Staying within my personal parameters for a "hunting" load utilizing ball powders (drop tube OK but no compression), basically, I can't get enough 760 into the case to come within 5Ksi of a factory round fired in the same gun.

THAT DOES NOT MEAN THAT WILL HAPPEN IN EVERY RIFLE. So this is not carte blanche for someone to just dump in 80 grains and go for it. Even assuming identical components, (and obviously, it does not pertain to any other bullet) anyone that starts at over 76 grains is an idiot.

Whether this is a powder/bullet combination phenomenon or whether we both have loose barrels, I do not know, but I would say go ahead and load on up to your 2500fps, obviously watching for pressure indications as you go. If you do get to compressing the powder, I'd advise a drop tube to eliminate that concern, although you may be able to get more in than I did if you use neck sized, once fired brass.

FYI, don't bother with any of the 4350s; you won't be able to fit enough in to get the velocities to where they belong.

FYI2, I have often seen where Fed215 primers actually gave less pressure than even standard primers such as CCI 200s. So back off again, if switching primers. Once again, velocities IN YOUR GUN will tell you what you need to know and which way to go, to stay within safe operating limits.

Idon't think I've ever personally run into the phenominon where adding powder by serveral grains didn't change the speed and and pressure of the load but I've read about it from very qualified people and believe it can happen. Also....it may be just as much a situation of strange powder lots as it is bullets....possibly even more that is causing it so I would say don't just kind of blame it on the bullet itself.

That's pretty interesting, I haven't loaded 760 or H414 in my .375. RL15 or 4064 has always been the ones that work for me in a .375. Mine, like Mike's won't take nearly as much RL15 to reach velocity as some folks are using, and I've been through several pounds, so I don't think it's a powder lot variation. Sounds like you need to stay away from the NF with slower powders like H414 and 4350.

I think that my comments about 760 in the 375 H&H came off a little more disparaging than I intended. I know that I have a tendency to come off like that and will concentrate more on keeping my normal grumpy, and generally negative personality, from affecting what I write.

The facts are, 760 gave the highest velocities with the lowest pressures of any powders that I have so far tried in the 375, although admittedly, I have not tried a great number of them. For a given velocity, that is near the top of what is expected from the 375, 760 was over 7000psi UNDER the pressures generated by RE15 to achieve those same velocities. That is a good thing.

I did not have the time to apply my usual, overly anal, test procedures. I used virgin brass and I expect that some of my variations were from different neck tensions that were noticed during seating. Again, using once fired and sized brass will overcome some, if not all, of the issues that were experienced.

From the limited amount of testing, I liked the powder (760) and hope to visit it again when more time is available for a more detailed study.

My only caveat (and this is more of a personal thing concerning ball powders in general), when using 760, would be to use a drop tube and not compress the powder. The drop tube (used proprly) will gain you, at least, an extra 4 grains of powder room, without compression. The fact is, depending on your rifle, you may not even need to resort to either compression or a drop tube. You won't know that until you try it and see what YOUR rifle is giving for velocities.

Note that I DID tell Safari to go ahead and load for his desired velocity. I made that judgement by seeing that the velocity that he wished to arrive at would still be at a considerably lower pressure than what would be expected if, for instance, he had been using RE15 and trying to achieve that same velocity.

In summary, I like the powder. It most certainly worth trying and, from admittedly modest experimentation, it appears to give very good velocities for very conservative pressures.

I hope that clears up some of my earlier ramblings.

Mike