Got a chance to shoot some quick ladder tests to establish max charges in my Valkyrie. Due to time constraints I was only able to shoot at 100 yards with limited rounds down range. I picked the 80 grain Berger VLD over Superformance and H414. I haven't seen much data in this thread for this bullet or these powders and I have a ton of them, so that's what I went with.
20" Larue with 1-7 twist 80 grain Berger VLD COAL: 2.271" CBTO: 1.777" (Jammed 5 thou) CCI .41 Primer New Federal Brass (H20 - 31.4 grs) Fired Federal Brass (H20 - 32.0 grs)
Results: I was surprised to see this much vertical spread on target at only 100 yards. Several of my bolt guns shoot ragged holes over a 2.0 grain spread at 100 yards and it's not until 300 yards that you see meaningful dispersion. Not sure why that is, but not really concerned with it.
It appears that with each powder there is a low and high node with a "scatter" in between. The "scatter" shot was exactly 2520 fps with both powders (coincidence, who knows!?) and the low node is between 2372-2470 fps, and the high node between 2560-2656 fps. I was also surprised by the linear increases in velocity, approximately 49 fps per 0.4grs of powder. I did not reach any pressure signs during these ladder tests, so I will explore slightly higher charges in the next round of testing.
So what does all this tell me... Avoid anything in the 2520 fps range, and H414 produces more velocity per grain of powder than Superformance (it's more efficient?). Neither of these powders are said to be temperature stable, so in the future I'll do some testing with other powders such as Varget, N540, 8208 XBR, BLc2 and AR-Comp. I know, some of those aren't temp stable either, but I'm curious... It's also nice having two nodes in two different powders that span about 100 fps each. That tells me this round should be very forgiving and stable if loaded to the middle of a node.
The next round of testing will consist of an OCW style test to better identify the high nodes. Most likely focusing on Superformance between 29.0-29.8grs (5 groups of 4 shots, 0.2gr increments). Then H414 between 26.6-27.8grs (7 groups of 3 shots, 0.2gr increments). As I mentioned I did not reach pressure max with either powder, so loading on the higher end will let me verify the outside edge of the node. If I reach pressure before then, I'll stop.
I did load some extra rounds for sighting in and fowling the barrel. The last picture is a decent group that makes me think this rifle has potential. Oh, by the way, I HATE FLIERS! (rifle will out shoot me every day!).
This was my "casting a wide net" approach for round one. New cartridge to me, and I picked a bullet and powders that did not have readily available load data. This allowed me to work up to max pressure quickly with limited rounds fired. Though I will admit I never reached max.
Round two will be more of an OCW style test in .2 gr increments. Loaded up, just need time to shoot it.
My understanding of a node is where the POI on target is similar or the same on the vertical axis (minimal vertical spread), and the muzzle velocity flattens out (minimal extreme spread). The 0.4gr jumps does make it harder to see the velocity sweet spot, but the target seems to show consecutive charge weights that want to group well (despite the large variation in powder charges).
Not to be rude, but a 100 yard ladder test is almost a waste of time and components.
I've performed lots of ladder tests, never chronographing a single shot. Their points of impact on paper tells me what I need to know. Yes, there are plenty of times MV hits a plateau, but the POI is more important in my experience. You're going to have a long road ahead if you're going to try all those powders and only use 100 yards. I would pick IMR-8208, step it in .3 gr increments, and test it at 300 yards, minimum. Most likely you'll find your sweet spot with less than 15 rounds fired. I've seen IMR-8208 be pretty consistent in a wide array of temperatures.
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I'm running a 75 grain ELDM at 2990 fps in my bolt gun and 3000 fps in a 22" AR. There's a lot more room above the low speeds you are shooting. It will also shoot better when you get the pressure up more. I'm not sure what methods you are doing for your load work ups, other than pressure testing and getting velocity readings, which is a start. Your vertical groups is due to your velocity increasing as you go up in powder.
I'm running a 75 grain ELDM at 2990 fps in my bolt gun and 3000 fps in a 22" AR. There's a lot more room above the low speeds you are shooting. It will also shoot better when you get the pressure up more. I'm not sure what methods you are doing for your load work ups, other than pressure testing and getting velocity readings, which is a start. Your vertical groups is due to your velocity increasing as you go up in powder.
Chad, what powders are you finding work best with 75-80 grain bullets?
My Quickload update came in and it has the Valkyrie. I was only running in the mid 40k PSI range which is why I didnt see pressure signs. Maxing out H414 should get me up to 2880 fps with the 80 gr Berger.
It looks like AR-Comp is going to work really well for the 75 and 80s. Loading up some test rounds this weekend .
I'm running a 75 grain ELDM at 2990 fps in my bolt gun and 3000 fps in a 22" AR. There's a lot more room above the low speeds you are shooting. It will also shoot better when you get the pressure up more. I'm not sure what methods you are doing for your load work ups, other than pressure testing and getting velocity readings, which is a start. Your vertical groups is due to your velocity increasing as you go up in powder.
Chad, what powders are you finding work best with 75-80 grain bullets?
I've played with several. And it really depends on how you seat the bullet in the Valkrie case. There are several of us modifying the mags and seating the bullet out really long. The powders for that will be different than when loading to mag length. We've played with powders from the Varget burn rate to H4350 burn rate. I've found ball powders or small extruded powders work best, and not your larger extruded powders (due to case volume). I'm adding the 224 Valkrie to my website, so I won't reveal what powder I'm running in that. But it is listed in several manuals. I'm also seeing the load data VERY conservative and the max powder charges listed are low.
Hornady and Hodgdon have some good data listed. It's a little light, but it will work well.
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