IMR 4064, and the .308 Winchester should we wed in Holy Matrimony. If you cannot get a decent grouping with a .308, and 4064 you are a horrible shot! It is a medium burn rate extruded (stick) powder. It has been around for some time, and is one of the best known powders to use for nonmagnum 30 calibers.
I personally have used 4064 since I bought my very first 308, and it has been my go to for all my 308's. I use various powders like Varget, IMR 8208XBR, BL-C(2), etc but seems like the 4064 is always pushing those copper pills more then the other powders.
Some people will complain that you can buy all kinds of new powders, with with higher velocity, or can take heavier bullets, etc, etc. Which I do have most of those "new/better" powders. from 147 grain to 168 grain all you need is IMR4064, unless you are using a 168 grain mono metal bullet like the Nosler E-Tip or Hornady GMX. Then throw in a pound of Varget or 8208XBR for those hunting rounds, and you have the perfect .308 setup.
I have used IMR4064 in .223 Rem, 5.56NATO, 7mm Rem Mag, and .308 Win. Being extruded, and standard cut it is possible for flakes to get caught up in the bottleneck of a 223 sometimes, and out of both 22 caliber rounds gave okay average results. 7mm Rem Mag it is a great shoulder saver when not needing to really reach out with true magnum loads.
Now we get to the .308 Winchester.
My first bolt action deer rifle was a $200 Walmart special that you were lucky to get a 20 round box of commercial ammo to stay within a 10" target at 100 yards. My handloads of IMR4064 with 155 grain Hornady BTHP, and 147 grain pulldowns I grouped 1" at 100 yards all day.
My current deer rifle that I also use for casual & fun long range shootings is a Ruger American .308. I had the pleasure of taking that rifle to a truly long distance range with targets all the way out to 800 yards a few years back. I brought my trusty .308 with my standard load of a Hornady 155 gain BTHP being pushed my a moderate load of IMR4064. Now this was a special treat for me. The reason being the only ranges where I live that go above 100 yards cost several hundred dollars a year to join, and only certain members are allowed to shoot past 100 yards. Our shooting past 100 yards here was in the fall after they had cut hay fields at my wife's families farms. We go out to those empty fields, and hang frying pans way off in the distance, walk back to the shooting table, and spend the day shooting frying pans hanging from trees. We never measured yards or anything just me, my high school hunting buddy, and sometimes my boys or wife out having fun.
As I sit down in the shooting booth at the range I kind of look around. It is me, my youngest son, the gentleman who brought us, and someone else who was already shooting. I am sitting next to a guy who is shooting a rifle that the scope alone cost as much as 2 to 3 months worth of my monthly mortgage payments. You feel kind of out of place sitting next to someone shooting a rifle that the entire setup was close to $15,000. So I tap 100 yards, sub moa easy as usual with that rifle, and those handloads. I decide what the heck I will try to see if I can hit 600 yards at least once today. Now I rushed, and yanked the trigger on the first shot, and new I did as soon as that 3.5lb trigger broke. So I collect myself, get my breathing inline, and wait for the right time to squeeze the trigger. Then with a bump back on my shoulder, and a muzzle flash I sent that copper coated pills off on its journey. I sat there thinking "Just once. I just want to hit it once today. Even if it takes me all day I will hit it once.". Then suddenly off in the distance a sudden "PING" comes echoing back. So thinking "Okay what the heck give it another try for fun, but I can never do that again.". Squeeze that trigger, feel the bump against my shoulder with the muzzle flash, and another copper pill on its way. Then yet again "PING" echos back. I look over at the gentleman who brought us, and asked him if he will spot because I can't be hitting 600 yards like that. I shoot again "PING" I load another mag, and line back up. Squeeze the trigger, "PING", "PING", "PING", "PING" He had confirmed that every time it was a true hit on steel. At that point I tapped out, and said "I am done shooting for the day." With the excitement I was containing, and how my heart was racing I knew any shot I took after that was going to be way off because I was way too excited.
That day set a true trust, and confidence in my handloads, and it also reassured my of my shooting ability.
IMR4064 has worked wonders in my rifles, and it has been like a romantic relationship or long lasting intimate marriage. The .308 Winchester, and IMR4064 were meant to be together. If you have a .308, and have never heard of or yet to use IMR4064 the advice I give you is "Buy this powder! Your .308 Winny will love you for it, and make sure it takes care of you in return.".