We don't care, and most don't care we would guess, about metering, because a lot of people "hand" meter, and charge 1 at a time, carefully. If you do this, metering means nothing.
Reason #1 Velocity: If you look at a reloading book for 223/5.56 you will see using ~50-65 grain bullets that Benchmark is near top velocity, or it IS top velocity at same pressure. So its top tier here. Now other powders can compete in the velocity front with Benchmark. Some are AR Comp, but most notably, what we think is pretty much "King and Queen" of Velocity in 5.56 is Accurate 2230 and Accurate 2460. Accurate 2230 can be loaded to near 26 grains using 55 grain bullet and that is up around 3300 FPS in a 20" barrel. That is top tier. Accurate 2230 has "similar" burn rate to Benchmark and AR Comp as well.
Reason #2: Case Fill. Benchmark, using a 55 grain bullet would slightly need compression, but no big deal at all, when you use max charges of near 25.5 Grains. And you would not use 25.5 grains of powder with a 55 grain bullet, because it is far more accurate and great velocity using 25.0 grains, across every gun I ever tested, every 55 grain bullet. And using 60 grain V-MAX, 60 grain Berger and 62 grain bullets, it still liked 24.5-25 grains of powder, which we think is still under or near max load and lights out accurate. Benchmark is like the "perfect" fill in the case, with almost every bullet you can put in the rifle, that is 50-77 grains. Accurate 2230, since it is a small grain ball powder, as well as Accurate 2460, have better case fill characteristics than Benchmark or AR Comp. You can put 27 grains, for example, in a 50 grain bullet, loaded to NATO pressures, but you cannot do this with Benchmark or AR Comp because those powders start overflowing the case when you get near ~25.5-26 grains depending on what case you are using.
Reason #3: Accuracy. This is where Benchmark starts to run away with the title. Accurate 2230 and Accurate 2460 are arguably better Velocity and Case fill than Benchmark or AR Comp, but they are simply not as accurate as Benchmark in our thorough testing. AR Comp is "comparable" but we think its just marginally less accurate, and when you test dozens of back to back, same gun, same load tests on same day, you start to notice it, slightly. Benchmark is simply top top tier in Accuracy using 50-65 grain bullets. I have achieved top accuracy using 55 Grain Blitzking, 55 grain Berger, 55 Grain Hornady V-Max, 55 Grain Nosler FB Tipped, 55 grain Hornady FMJ, 60 grain V-MAX, 60 grain Berger, 62 Grain Speer Gold Dot, 64 grain Game Changer and Game King from Sierra and its great accuracy using 69 and 77 grain Sierra Match King. Although for 69-77 better powder choices would be Varget, or Shooters World Precision Rifle, or IMR 8208 XBR, or Reloader 15, or Norma 203B in our view, although those last 2 are less temp stable.
Reason #4: Temp Stable. This is only important with Rifle, and only really an issue when you are shooting past a few hundred yards. So for Hunters who take game from 50-200 yards, this doesn't matter hardly at all. The longer range, the more it matters. For example. A non temperature stable powder, such as CFE 223 has large change in velocity every single degree F change. So CFE 223, over a 100 degree change in temperature, would be somewhere around ~175 FPS change. 175 FPS change? That is gigantic bullet drop difference. Take a powder that is temp stable, such as Hodgdon Extreme Powders, or something moderately temp stable, like Ramshot TAC, you have much less affect. Benchmark for example, over 100 degrees would be slightly under about ~50 FPS. 50 FPS is less than many people's reloads extreme spread. That is near as good as it gets. Here are some temp stable powders for people that don't know:
Varget, Benchmark, Hodgdon 4350, Hodgdon H4895, IMR 8208 XBR, AR Comp, Reloader 10x, Reloader 16
In our view, if you are a rifle user, there is "zero" downside, except maybe price, for picking a temp stable powder, as they are superior to non temp stable powders, overall. Benchmark is not the most temp stable, perhaps H4350 is, then Varget, but its good enough. Now you know why H4350 and Varget are so insanely popular. BUT, Shooters World Precision Rifle, we think is better than Varget, and temp stable as well. Please consider this.
Reason #2: Cost? Temperature Stable powders like Benchmark, are typically $5 or so more per pound then non temp stable, generally. Hodgdon Extreme powders are top tier powders. Benchmark is one of them, and also similar H4895 is another one.
This is our opinion after testing nearly everything, and re-testing, and re-testing, and over and over out of many guns.
Benchmark. KING OF THE 5.56 POWDERS. Here is a ranking....of our personal favorites...top 10 probably...
- Hodgdon Benchmark
- Alliant AR-Comp
- VV N133
- Shooters World Precision Rifle
- Hodgdon Varget
- Alliant Power Pro Varmint
- VV N135 probably
- Winchester 748
- Accurate 2230
- Ramshot TAC
Honestly when you get down to #6-#10 those are all like toss up and good for slightly different reasons.
Powders we don't recommend for 5.56? They can be used, but issue with them is listed
- H322 - Too fast (burning)
- VV N130 - Too fast
- Alliant 10X - Too fast
- Alliant Power Pro 2000 - inconsistent results, extreme spread
- Hodgdon CFE 223 - inconsistent results, extreme spread
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