Bob...
I did extensive research (and worked up many loads) using IMR3031, IMR4895, IMR4064, Varget and H4895.
I found the IMR4895 was THE most accurate powder and gave me the highest muzzle velocity of any of the powders I tried.
However, there was one problem... the velocity got slower and SLOWER with each new pound can of IMR4895 I purchased beginning in 1995 (avg. MV = 2715 fps using 41.5 grains with a 150 grain Nosler Ballistic Tip bullet), then again in 1999 (avg. MV = 2708 fps)... and again in 2002 (avg. MV = 2685 fps), 2004 (avg. MV = 2665 fps) and finally in 2006 where the average muzzle velocity was only 2547 fps with the same load (41.5 grains of IMR4895... the MAXIMUM listed load) as I had been loading since 1995. However, this load was chronographed at just 26�F... not 85�F. But a "test load" I brought with me the same day which was one of my hunting loads from the can of 2002 IMR4895 chronographed at 2630 fps on the SAME DAY that the load of 2006 powder chronographed at 2547, so there was a REAL and OBVIOUS "difference" in the powder's performance from the 2002 powder to the 2006 powder.
All muzzle velocities were from my chronograph... and, meanwhile, other calibers like my varmint load out of my heavy barreled Sako in .222 remained a consistent 3199-3210 fps over the years using 21.8 grains of Vihta Vouri N-130 (Max. listed load = 22.1 grains of VV's N-130) so there didn't seem to be anything wrong with my chronograph.
I hated to try other powders because at a load of 41.3 grains of IMR4895, I got a 3 shot group of just .112 inches (2002 powder) and many 3-shot groups under 2/10ths of an inch at 50 yards using the MAX. load (also my hunting load) of 41.5 grains which yielded a "best" 3-shot group for my hunting load of .191 inches at 2685 fps in 2002. BUTTTTTTT... a MV in the mid-2500 (2006 powder) just wasn't good enough, so the search of a new powder began.
I found a maximum load of IMR3031 (40.0 grains behind a 150 grain Nosler Ballistic Tip bullet with a standard Winchester large rifle primer in Winchester cases) yielded a good muzzle velocity (2665 fps) and good accuracy for 2 out of 3 shots, but there was ALWAYS one "flyer" an inch or more out of the group.
I found that IMR4064 showed pressure (cupped firing pin dent in the primer and flattened primer) at close to maximum load and the group size wasn't anything to brag about.
Varget was a major disappointment... best MV was a hair over 2600 (2607 fps as I recall)... but even an additional 1/10 of a grain of powder over the max load didn't show any pressure and only raised the MV to something like 2615 fps.
Finally, I tried H4895 and was pleasantly surprised. A load of 40.8 grains (.1 of a grain UNDER the maximum load) yielded only 2635 fps, but it was a very consistent "2535 fps" with a standard deviation of only � 3 fps (+1 fps/-2 fps) and decent accuracy (can't remember the actual 3-shot group size, but it was around a quarter of an inch or so... plenty good enough for deer under 250 yards (my self-imposed maximum hunting shot range).
An additional "PLUS" with the H4895... it is one of Hodgdon's "EXTREME" powders which means the MV it produces is NOT effected by TEMPERATURE... and this is why the rather low MV of just 2635 is ACCEPTABLE.
I found with IMR4895, the SUMMER (85�) muzzle velocity was 2685 fps, but the HUNTING WEATHER (20� to 30�) MV was only 2630 fps!!! So the H4895 produced MV of 2635 was fully acceptable since it will still be a consistent "2635 fps" in the cold weather as well because it is a Hodgdon EXTREME powder.
The gunwriter, "MuleDeer", who posts here told me that the low muzzle velocity yield of the 2006 IMR4895 was probably just a "powder lot variation", and while I truly respect most of his thinking, I don't agree with him on this "powder lot variation" due to the
continuing, slowly
lowering muzzle velocity since 1995 because this "step-down" of muzzle velocity almost seems "planned". It SEEMS too consistent to NOT be planned, but WHY?!?
Buttttt... that's another battle for another day... so I decided to "move on"... !
When testing the load's velocity in the cold weather using the powder from the BOTTLE like Hodgdon uses which was purchased in 2006, I also brought along a few rounds of my hunting loads using the powder from the can of IMR4895 purchased in 2002 and tested the muzzle velocity of my those hunting loads of 41.5 grains of 2002 IMR4895 powder against the same load of the newer (2006) IMR4895 and while the new IMR4895 yielded only 2547 fps, the older hunting load of the same amount (41.5 grains) of the older (2002) IMR4895 yielded 2630 fps on the SAME DAY a FEW MINUTES LATER as the new IMR4895's 41.5 grain load yielded only 2547 fps.
Therefore, while it may have been the powder's "lot variation", it was more than I wanted to deal with since the same load (41.5 grains) of IMR4895 had been slowing down with each new can of IMR4895 since 1995 and I'd had enough... and the search was "on" for a new powder which ended when I tested H4895.
Of course, each rifle is a "study" unto itself... and what may work well in my Model 99 may NOT work as well... or may work BETTER in your Model 99. The ONLY way to find out is to try different loads and different powders and see what you get.
I'd suggest you try IMR3031 and Hodgdon's H4895 and work up to maximum published loads and see what kind of accuracy you get. Keep good written records so you can review them months or even YEARS later and still get accurate details.
I've got pages and pages of notes and details, but it is far too much to enter here. Anyway... a load of 40.8 grains of H4895 works for me... decent muzzle velocity and decent accuracy... and no high pressure signs.
Ya can't beat that with a STICK!!!
Strength & Honor...
Ron T.
