Thursday, May 27, 2010

Load Development, Ladder Test

When we get a new gun, we want to find out the load that it likes to shoot. The old standard method was to search all the available data for a workable bullet/powder combo, then load some ammo in increments, usually five cartridges each, in varying powder weights. For example, you might load five cartridges at 30 grains, 5 cartridges at 30.5 grains, five cartridges at 31.0 grains, and continue until you've got 30 or 40 rounds of ammo. Then, you get out to the range and shoot them, trying to determine what combo works best. This is sometimes a frustrating technique because it burns a lot of powder and uses a lot of bullets. In these hard economic times, bullets and powder are expensive, if you can find them. The ammo shortage of '09-'10 continues to haunt us.

I've been casting about for a better way to conduct load development and I went over to the Accurate Shooter website and found an article entitled Long Range Load Development. I'm not benchrest shooter, but I understand that those folks with the funny looking rifles have thought a lot about rifle shooting and they've done some great things with accuracy. Perchance I can learn something from them.

The concept is fairly simple. Pick a powder/bullet combination, then start low and load in increments. It makes sense that as the powder charge increases, the bullet goes faster, so the bullet is going to strike higher on the target. At some point, the barrel harmonics should show two or three bullets striking the paper fairly close together. That's your sweet spot for that powder/bullet combo and further load testing will show where the most accurate load is for that combo.

I've got a new .30-30 I need to test and I've got some range-time scheduled for tomorrow. Today, I picked a powder bullet combo and looked in the literature. From lowest charge to published maximum is 3.2 grains of powder, so I loaded six cartridges at the minimum for sighters and started stepping up the charge in 0.3 grain increments to the maximum. If the benchrest guys are right, then the shots should march up the paper. At some point I'll find the sweet spot in that barrel and I'll know where to start for further load development.

Or, I'll find out with 15 shots that the barrel doesn't like that powder/bullet combination. Either way, I'll learn something tomorrow morning.

1 comment:

Old NFO said...

Old school, but it's amazing how well it works :-)