Optimal Charge Weight Help

[EdP]

Thanks. I was debating which to do first. This might be a dumb question, but I'm new to this, so how do you choose the powder load you use to test seating depth?

Like R&M said, you can just pick a safe middle of the road charge.

I can generally find a good seating depth by shooting 4 groups of 5 shots seated at .005, .010, .015, and .020 off the lands. This range of seating depths works for me using tangent ogive bullets. Other bullet profiles/designs such as secant ogive or monometal may require a different range. One of those 4 groups will be noticably better and that is the seating depth I use and develop a powder charge around. I often see velocity increase as the bullet is seated deeper in the case. R&M says he doesn't see this and I don't always see it. Decreasing velocity as the bullet is seated further out (with the same charge) is discussed in various articles by Brian Litz. This is due to decreased pressure from having more free volume in the case, BUT REVERSES if the bullet is loaded very close to or touching the lands, and then pressure can increase considerably.

So I determine seating depth first, then charge to find a velocity node. Done the other way around you may see a velocity change after finding your charge/velocity node due to changing seating depth. There are folks who do it both ways successfully.

 

[Pony Soldier]

When I start out, I load from the lower recommended load and then work up at .5 gr increments with groups of three. After I see the tightest goups, I drop back and load the next series at .1 gr increments in groups of three.

Each series will group tighter but when you go past the optimum load the groups will open up. Once you pick the load with the tightest group, then look at how it performs at varying distances. I do my initial work at 50 yds then step out to 100 then keep stepping out at 100 yd intervals. My areas rarely give me shots greater than 400 yds so I don't get excited to fine tune over that.

Some powders are not necessarily consistant between lots so you may have to do it all over when you change lots and certainly when you change bullets. I tried some Eld-x 175s a couple years ago. They gave me nice tight groups at 50 yds but when I went to 100 they opened up to 8 inches. Obvious that my rifle didn't like them so I threw them out.

Once you find what your rifle likes, test them on performance. If you can consistantly hit with them and they kill without tearing up your meat buy enough powder (same lot) and bullets to last you because things change but not always for the best.

That is what has worked for me and it took a long time to get there. I try things occasionaly out of curiosity but thankfully I bought enough bullets to last me because they don't make them anymore.