Go figure....Proof is in the shooting.

[berettaprofessor]

Sometimes, I wish the Reloading Gods would come down and explain some of the inconsistencies....

Yesterday, I finally chronyed a 308 load that I had developed in a ladder test for my AR10; I also tested a few rounds of a 42.0 grain Varget load (not ladder developed, but someone else's favorite load suggested on the Internet). Same 168gr Hornady Match bullet in both loads and I also shot a pair of 5 shot groups of each with the AR and with a Savage Axis for comparison.

Benchmark: 2342fps, ES 49, SD 19.7
Varget: 2457fps, ES 19, SD 7.3

The Benchmark load is under 1 MOA in both guns. The Varget load, which from the chrony data should be more consistent, is a 2+ MOA with both guns. What the heck?

 

[ArchAngelCD]

I have always said low ES and SD numbers don't always translate into a accurate load. In my mind your results are not surprising. Low SD numbers are more important in longer shots. (600+ yards) Even that is limited. The lower SD numbers in 2 equally accurate loads will show better accuracy mostly in longer shots.

 

[Allen One1]

Maybe it proves that you are building good ammo but you are off the accuracy node. You did say you didn't run any testing on that load. What would happen if you slow that Varget load down into the 2342 fps range.

This is interesting.

 

[Arkansas Paul]

Not really surprising.
Some guns like some loads better. There's not always a rhyme or reason that you can put a finger on.

 

[Varminterror]

If you’re shooting at 1,000yrds, that lower ES load will shoot the smaller group. If you’re not, then consistency in muzzle speed is less critical, and then load development based on group size alone matters.

What kind of “ladder” did you shoot for your load work up? I assume NOT an Audette ladder test, but rather some form of interval chargeweight test based on group size?

 

[Hooda Thunkit]

Something about the way one powder burns versus how another powder burns can have an effect on the projectile.

Personally, I don't lose sleep over why one powder or load works better than another.

Just go with the flow.

 

[edwardware]

Sounds like you've found a low ES/SD charge; now try adjusting seating depth to find a barrel vibration node.

 

[murf]

i'd drop the varget velocity down to the benchmark level before I started to mess with col (a good idea, imo).

murf

 

[Walkalong]

If you’re shooting at 1,000yrds, that lower ES load will shoot the smaller group. If you’re not, then consistency in muzzle speed is less critical, and then load development based on group size alone matters.

Agreed.

 

[berettaprofessor]

Varminterror; no, I haven't done an Audette's, but you're right, it might be interesting with that Varget load and I think I'll try. I've always just loaded 5-10 rounds in increments and looked for group size, which is how I found the Benchmark node. I've never used Varget in 308, but given that SD, it might be time to try. I'd also like to use another bullet; maybe an A-Max or ELD if I'm going to work up another load for this gun.

It was hot out today; near 85 when I was shooting and sun bad enough to blister. I've read somewhere that Varget is more temperature stable than Benchmark. Could that have affected the spreads?

For those who want me to drop the Varget velocity down, yes, it might be interesting, but that Benchmark load is near minimum; I'd rather bring up the velocity of the Benchmark, esp for longer distances...but the rifle likes what it likes, I guess.

I don't shoot long distance, but I'd like to. The only range in a 40 minute drive is a mere 100 yards. I think I'd have to drive 2-3 hours, or find a ranching friend, to shoot 500.

 

[Blue68f100]

Varget is one of the more temp stable powders out there. It may be the lowest one if not a close second.