Ian
Notorious member
H414 is good but use Winchester primers with it. IMR 4064 or 3031 is good, Varget is good, RX-17 is good, even stepping down to 4350 and filling the case a little more is good. Lots of options here. The trick is to find a powder that lights quickly and consistently with light resistance to bullet movement (low neck tension and a little bit of bullet jump to the ball seat) yet gives the gas volume and push you need for good muzzle velocity, then tune it to get your bullet exiting at the upper pause in muzzle whip. Use starting jacketed bullet loads with the powder and j-bullet equivalent weight you're working with, work up and look for that vertical string. Once you see a clear vertical dispersion at 100 yards minimum (200 is better), add just a pinch more powder until it closes up. Walter does ladder testing, same concept but fewer data points. What you're doing is establishing a consistent internal burn and timing for your system and then tuning the muzzle exit timing to the point in the barrel whip where the muzzle is the most still for the longest duration, usually at the top of the whip. Basic long range tuning stuff. If you're seeing lots of horizontal or open patterns, your problem is at the reloading bench either with powder choice or more likely with dynamic bullet fit (meaning the bullet is either getting crooked or damaged during the launch, has voids or casting defects, gas check seated crooked or off center from the shank casting too large, bullet too big for the throat entrance, case neck not concentric to case body, bullet seated crooked [runout], seating depth not correct for the system, or the alloy and initial pressure the powder is making are not jiving).
This all assumes a sound rifle that shoots the way you want it to with jacketed bullets.
This all assumes a sound rifle that shoots the way you want it to with jacketed bullets.
