Varget vs imr 4064

It depends on which cartridge. Generally Varget is MUCH less sensitive to heat in rounds like 308. But many powders that are less sensitive to heat in one cartridge may not do so in others.

In 308 and many other cartridges expect Varget to change no more than about 1/2 fps for each degree of temperature change. It works both ways. Develop a load at 70 degrees and it will be slower at -20 and faster, and possibly over pressure, at 110. RL-15 is very similar to Varget BTW.

Powders like 4064 will change velocity 1.5-3 fps for each degree of temperature change.

I use all 3 powders in my 308 loads. To be honest with the best loads I can't tell a bit of difference in velocity and very little in accuracy. With the right loads I believe 4064 might be ever so slightly more accurate and at temps between +20 to about +80 there isn't enough velocity change to worry about. I tend to use 4064 when I'm trying to squeeze out the last bit of accuracy, but use the others in hunting loads where I may encounter more temperature extremes.

If I were getting significantly better accuracy and/or speed with 4064 I'd use it anyway and just deal with the loss of velocity in cold weather. As long as you're not right at the upper limits of, or over, book loads going over pressure in hot temps won't be an issue.
 
From load data, take the difference in the highest and lowest velocity for your cartridge with each powder and divide it by the number of grains difference in charge weight used to produce that difference in velocity. This gives you fps/grain in the normal load pressure range. Generally speaking, the smaller that number is, the less sensitivity the powder will have to things that affect pressure, be it charge weight error or temperature. It's not exact, but you can usually use it to tell a powder that will be more picky about conditions from one that will be less so.
 
I use Varget in my .223 and Imr 4064 in .308. I find both are very temp stable. Off the top of my head, according to a test spreadsheet I downloaded on the topic, I think Varget has a temp sensitivity factor around .3 and IMR 4064 around .4...so it takes about 2.5 degrees to increase IMR 4064 by 1 fps and Varget takes about 3 degrees to do the same.

I use 4064 because it works great in .308 and it is what federal uses in the 175 and 168 gr gold medal match .308. But Varget is fine too and I use it in .223 but wouldn't hesitate to use it in .308
 
I have never concerned myself with sensitivity in the powder. My hunting loads are generally developed in early to mid spring. If the temp outside is 70* plus, I'm not hunting in it any way. Same thing with the cold. If it get's down about 20* and a bit of wind, I'm in the house watching a ball game! My only varmint/predator rifles now are both 243's and I pretty much shoot them even on the 70* + days but not on the 20* days. I found in 308's there's several powder's that work really well. IMR4064, H335, BL-C/2, W748 and I've heard IMR4350 is good to, never tried it. Didn't seem to matter which of those powder's I used, they just worked well. I think if for some insane reason I was to go hunting somewhere where the temp even hit 80*, much less 100*, I'd work loads up late spring to mid summer.
 
It is not uncommon to get Temps in the 80s in black powder and early in rifle season here in eastern NC. It's not the temperature but the mosquitoes that will get to you. It is wierd to kill a nice buck sweating in the stand. I do test my 4064 hunting rounds for my .308 in late summer. I have never used Varget. IMR 4064 has always been available and my go to powder in .308.
 
Varget will be "more" temp stable than IMR4064, however IMR4064 is about twice as temp stable as IMR4895 and much more so than Reloader15.

I've used both, and got better accuracy from IMR4064, but I'd say buying a pound of each is a cheap way to figure out what works best in your rifle.

Jimro
 
I have never concerned myself with sensitivity in the powder.
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Neither have I. Those extreme powders may be less temperature sensitive than non extreme powders, but I have blown primers with them, just as I have blown primers with IMR 4064. I don't know and cannot verify the less temperature sensitive claims for these powders and you know what, I don't care. Shoot enough cartridges in hot weather and you will figure out that pressure is not your friend and that loading to maximum levels produce stuck cases and pierced primers. Regardless of powder, I back off whenever I see pressure indications. I don't want to have to pull out the cleaning rod and knock the case out of the chamber, for one thing, it ruins my scores in highpower matches. I want accurate rounds that give reliable feed and extraction. I can't count the number of times I have developed loads, with regular powders and the so called "extreme powders", only to use them in a match and find overpressure loads when the rifle heated up. I don't know why I did not experience the problems developing, but next time I reload with that combination, I cut the loads. And I keep cutting till I have zero extraction issues in all conditions.

What these manufacturers of powder are encouraging is something called "Normalization Of Deviation" http://www.huffingtonpost.com/great-work-cultures/normalization-of-deviatio_b_13059988.html They teach you that you can get closer to the cliff edge because they have made some whoop de do great powder, but what you will find, is that you will fall off the cliff, and a little sooner than you expect.
 
Varget / 4064

There"s nothing better than 4064, 4350, etc. but I'm working with Varget because it keeps my barrels cooler. Ten shots with Varget about equals three shots of 4350 in my 6mm, by the feel of hand scale.
 
Ran both Varget and IMR4064 in my 308. Stuck with the 4064. With load work-ups when temps were in the 40's and shooting with temps in the low 100's, my groups stay tight. POI may change a bit but it's easily adjusted for.
Then again, part of the reason may be that I had a friend that gave me 8 lbs of I4064 in the metal 'keg' that his grandfather had when he passed away. Adding that to the 9 lbs I already had, I4064 gets tried in just about everything now.
 
Hmmm. I've loaded Varget, RL#15 and IMR4064 in my .308's. All were accurate, with 4064 being the most accurate. MV was all very close, with RL#15 having a slight edge in MV. All very good powder's in .308. Never shot in extreme heat or cold, so really can not say much about temp sensitivity, other than the military uses[or used to] RL#15 in their M118 sniper rounds because of very good accuracy and insensitivity to extreme temp changes.
 
When I first started reloading for my Rem 700 LTR 308 . I started with 3 different powders , Reloader 15 , Varger & IMR 4064 . My rifle shot better with 4064 , RL 15 & Varget in that order. I only use 4064 168 gr. SMK ,Federal & CCI BR 2 primers . Brass I use Federal , HSM & ADI. All full length sized to no longer then .002 base to datum line . Works for me.
 
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All very good powder's in .308. Never shot in extreme heat or cold, so really can not say much about temp sensitivity, other than the military uses[or used to] RL#15 in their M118 sniper rounds because of very good accuracy and insensitivity to extreme temp changes.
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Well...here is some history of M118LR using Reloader15, it was chosen because it was better than IMR4895 for accuracy pushing the 175gr SMK. There have been 4 powders used in the M118 series, IMR4895, WC750, Reloader15, and IMR4064, and they were used pretty much in that order. The problem with Reloader15 became very apparent in the "War on Terror"

Originally IMR4895 and WC750 were used with the 173gr FMJBT match bullet (same bullet used in 30-06 M72 match ammunition). With the switch to the 175gr SMK Reloader15 was chosen, then replaced with the M118LR Mk316 Mod0 which went with IMR4064 because it was much more temp stable. The biggest problem was M110 sniper systems were getting a lot of brass stuck in the chamber, essentially turning the semi auto sniper system into a single shot, which was not good.

The M118 series has also used two different grades of brass (Lake City and Federal for Mk316), as well as two different powders (LC milspec primers and Fed GMM primers). So between multiple sources of brass, primer, powder, and two different bullets, you can say that the military has been messing with the sniper ammo quite a bit.

Jimro
 
Well, how about that. Learn something new here all the time. I wonder what powder the military uses now? Thinking that they use the .338 Lapua or .50 BMG, must be different nowadays. Things are always changing.
 
The military uses 308, 300 WM, 338 and the 50 (as well as the very outdated 5.56)

Yep, they keep trying things to make things better, not always successfully.

Vietnam on a small and hopefully less lethal scale.
 
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