Just conducted a test this morning. Back in the summer I did some load development with Reloder-22. It was accurate and with 55.5 grains pushed the 225 ELD-Match bullets to 2575fps. The temperature was about 90*F and humidity was about 85%-ish.
When I saw how cold it was going to be, I decided to test how much velocity would drop. I loaded up four rounds in the same brass, same primer, same bullet, same charge. Left the ammo and the rifle outside all night. This morning it was about 6*F and 65% humidity. I fired the four rounds over the Magnetospeed. My average velocity dropped to 2475fps, with an ES of 40fps. Yikes. RL-22 is out of the running I think. 100fps drop seems like a lot.
It's supposed to hit 4*F tonight, so I'm going to load up a few rounds with Superformance and see how that one does.
The other powders I'm trying are H4831SC, IMR-4955, and H1000. What are other's experience with these powders? Or are there others I should be looking at?
I think you will find the extruded powders like H1000, Retumbo, and VVN570, better suited for temperature extremes. Much more consistent velocities over extreme difference in ambient temps.
These powders are well suited for the 225 grain and up bullets due to a slower burn rate, but are harder to meter and work with. I use VVN570 for my .338 LM loads and it is worth the extra effort of extruded powder!
5 shot grouping. .338 Lapua Mag 100 yards. Lapua brass, SMK 300gn HPBT, CCI 250 mag primers, 91gn VVN570, 2814 fps.
Tested the Superformance loads this morning. Used 54.5 grains, which previously had gotten 2571fps at a temperature of 60-65*F. Today was same conditions as yesterday. Left rifle and ammo outside overnight. This morning the outside temp was -3*F. The ammo and rifle temp matched ambient. 4 shots fired with an average of 2463fps, ES of 80. This stuff was worse than RL-22. I kind of expected that being it's a ball powder, but as much as Hornady bragged on the stuff I wanted to try it.
With ball powders in cold temps you will likely want a magnum primer and the load needs to be worked for that specifically. I use magnum primers with ball powders as a rule. Helps with low temp ignition. Also makes them kinda touchy about being close to max when hot so... there's always a trade off. In my magnums I use a lot of US869. If you keep the cases relatively full of powder and bullet it seems to put down really good consistent numbers, though there is a definite temp / mv curve.
If you guys need help establishing your MVV curves email me at ballisticxlr at gmail. If you're able to use RL22 and not getting temp stability you want to look at RL23. That's the new super whiz bang version. I use it in my .243AI and I get ridiculously low SD's (5fps with solid batch to batch consistency) and temp sensitivity. It meters kinda poorly. Bridges and such and if you get an 8lb jug the first pound will be all over the map on granule size but it mellows out though I still hand weigh every charge out of necessity.
H1000 didn't do well for me. Groups never came together (gun specific) and MV's were a little loose. I've tried a lot of IMR powders in this class, not super happy with any of them except 4166 (IIRC, no coffee yet, the new one in middle burn territory). That has turned out 2-4fps SD's in a 6.5x55 and been very nice on the MV's with great temp stability.
As always check for applicability of the powders discussed above. They're being discussed as a class of slow burning magnum oriented powders, not specifically for any cartridge loading.
I'll have to look into RL23. I have run a M/V test with H4831SC and like what I saw. Just shooting prone at 65 or so yards all 20 rounds went into a group the size of my thumbnail. M/V numbers were good too. Next test will be IMR4955. Doing that tomorrow hopefully. I have some H1000 but I'm not sure it's going to work. Can't fit enough in the case with the seating depth I have to run. I've been considering having the throat cut a little deeper to make room in the case, and may yet do that. Just want to prove it's necessity first. Once you remove metal, you can't put it back.
I don't mind the metering difficulty. I throw each charge into the balance scale a bit light, then trickle up to where I want it. Because OCD. Once you get into a rhythm it's not *that* slow. Also will be experimenting with magnum primers.
Thanks for the input, and the offer. I'll probably take you up on it once I get my load established!
I am shooting the 225 eld match in my 300 win mag. I have settled on 68.5 grains of H4831SSC. It’s a little slow for what it’s potential is but the rifle or I shoot the best at this load. I ve logged at exactly 80 degrees and 80% humidity 2592 FPS and at 20 degrees 67% humidity 2488 FPS. All over a magneto V3. I am getting great SD it’s very predictable load and it falls right in line with REXs MV curve
I get great results with Varget and H4831. I rarely chrono my shots but impact point is usually never affected.