After noticing that the Hornady line uses temp-sensitive powders, I tried developing a load yesterday with Varget. I initially didn't want to use it due to QL showing the MV would be pretty low. I thought it may be better to have consistency over MV. The below results were shot at 100yds in the prone with Harris bipod and rear squeeze bag. Rifle specs are: JP Enterprises thermal-fit upper with 20" Compass Lake Engineering-chambered Criterion 6 ARC barrel which I asked them to set up for the 108gr ELD-M bullet. Daniel Defense DDM4V7 lower with TriggerTech AR trigger set at 4.5 pounds and Magpul PRS stock. Scope was a March 1.5-15x42 with MTR-4 reticle. Rifle weighs in complete at 14 pounds.
The factory Hornady 108gr ELD-M wouldn't initially shoot here in SoFla, so I took everything with me to Virginia. The temps were between 32-58F and both the ELD-M and the Hornady Black 105gr BTHP shot very well; largest groups were @ .750, smallest were @ .450 for 5 shots. Brought everything back to SoFla and the groups opened up again. So...On to Varget. I'll reload 26.2 through 26.9 in .10gr increments and see if I can spot the tightest of all. Then maybe play around with seating depths.
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Great data. Makes me want to take another look at Varget. I use Varget for more calibers and loads than anything else and keep a few 8 lb jugs on hand.
I don't think anyone considers 2520 to be temp stable, but for now that's what I have settled on for 6 ARC and .308. I've tried Varget, Lever, CFE223, TAC, and a couple others in 6 ARC with lesser results. Here's my best load so far-
6mm ARC, Berger 105 BT Target, 29.0 gn 2520 ** (essentially same results w/ 105 Hybrids)
24" Bartlein Barrel AR15 Series 24 Shots: 5
Min 2735 Max 2746
Avg 2739 S-D 4.8
ES 11
** Note that 29.0 is well within Accurate/Hodgdon limits but slightly exceeds Hornady 'semi' load data. Don't assume this is OK in your AR. I'm running a JP high pressure bolt and there are zero signs of pressure. Brass is holding up to several reloads on the same case w/ annealing before resizing.
I've seen a lot of traffic on the interwebs making negative claims about 2520 including temperature sensitivity, but I say let them keep jabbering- more for me.
Some anecdotes why I think this:
Couple days ago in 20-degree weather I shot .382 to .436 MOA groups at 100 yards once the barrel was warm. Cold bore group size was .477 MOA. Does similar in summer weather. The finer granules of 2520 are much easier for me to meter accurately than is Varget. POI not changing from cold to warm barrel.
2520 for .308 did very well for me in brutal Camp Perry heat at the Nationals a couple years ago. With a self built Bula M14 I shot a clean stage in slow prone and a 98/100 in rapids. I could have dropped a few points in offhand and still won but apparently I'm not particularly temp stable and could only grab bronze
. Sunny, ~102 degrees, and typical nasty humidity. After slow prone the barrel was already blazing hot and I'm sure the chamber was getting pretty warm.
I do keep my mags out of the sun, but I think the OP does that as well based on his post.
