Looking for some specific information on the use and characteristics of this powder and then comment of what I have found with a simple search. The reason for these questions is because a friend at the range gifted me a pound to try out. He swears by the stuff.
So basically I have two questions; one, does this powder perform better at low or high ends and second does it work better with light or heavy bullets? This will be used in a 223 bolt gun with a 1:9 22" barrel and 62gr and 68gr bullets.
The few quick searches I'd done with the first one to Hornady #10 book as the bullets are both Hornady. Their data shows 21.7 Start and 24.9 as max for the 62gr.. Which is what I am working on right now.
The web searches mostly come up with 55gr. bullets with people stating a 24.5gr to 25gr start load! WoW that is a far cry from what Hornady lists. Even found a few threads with 62gr. bullets in AR's with short barrels and again higher load data,
There were posts from a number of other forums and even a few old ones from this forum, dating back from 2011/2012.
So also I do not need to start a discussion on other powders that you found that work because I already have a powder that I use and like greatly. Now going to explore this powder as a courtesy to my friend for the gift.
Varget in 223 max load is almost uniformly a compressed load. It's like one of those things where you can't really go wrong even if you top the case off with it... It's slow burning for 223. (no I don't recommend dunking your cases in varget and seating bullets... lol, although, that's kinda what the max load looks like on a lot of lighter bullet weights.)
I found Varget is up there with 4895 on performance for most of my 7.62 rifles, it burns clean and is really consistent. One of my friends found it was the most accurate load in his rem 700 for 1k shooting (although, he's really pushing the limits on what you should do with a 308).
Can it be used for 5.56? Yeah, maybe not the most ideal though, all depends on your rifle and the timing of the harmonics.
You can't ask for "what powder is best for my rifle" because .. every barrel is different.
When you spark a cartridge off, your barrel vibrates. Whip, is a more appropriate way to look at it. It's somewhat flexible and that ignition and rapid acceleration of the powder burn will cause it to vibrate. This is measurable.
The end of the barrel moves to and fro (how much depends on your steel, thickness, and a host of other factors specific to *your* barrel).
Your "most accurate load" in your rifle will then depend on these things:
#1 Consistency in initial burn ramp up - this depends on your brass, your chamber, your flash hole, your primers, your neck tension on the bullet, your leades on the throat, your rifling, and so on. Varies from barrel to barrel, case to case, and bullet consistency in that lot, etc. You can iron out a lot of variables with weight sorting, flash hole uniforming, primer pocket uniforming, and consistent neck tension (neck turning / bushing dies / etc), if you want to go whole hog and spend an enormous amount of time on brass prep, only to find out that it doesn't matter one bit (or matters the world?)
#2 Time to bullet ejection and velocity at time of ejection (the initial variability causes a big spread here, if you are inconsistent on any of the above)
#3 Precision of your muzzle cut (if there's knicks, burrs, etc in the crown of the muzzle)
#4 Where that barrel is on it's particular harmonics as caused by the combination of #1 and #2.
(for gas operated, your gas position and what effect this may have on the remainder of the bullet's trip through the barrel matters now too)
So your barrel is going to flex, vibrate, and whip around a certain *way* when the conflagration mounts inside your chamber and up your barrel.
At *some* point, in nanosecond timing, assuming it's a good barrel, it will *re-cross* the exact point it had at the time the primer detonated - matching your point of aim. Assuming you do your part and the rifle is recoiling precisely straight back (e.g. you have no weird torsion on it from your shooting posture), that bullet will leave at a set velocity at exactly the same spot each time.
If your burn rate is off (due to any of a dozen or two factors, from powder charge, to flash hole dia difference, to etc..etc) and your velocity standard deviation is wide, those bullets are going to be leaving at different *times* in relation to your barrel's harmonics, and your group opens up. You'll also see (at a longer range) that the shape becomes oblong, vertically.
So, no one but you can answer "what powder will be best in my rifle" because.. it depends on dozens of factors *and* one of those is your specific barrel.
Is varget good?
Yes.
Is it the best powder you can find for your gun?
Maybe? Depends on everything else, really.