Group Numbers for Load Development

[roo_ster]

Howdy:

I have just loaded up 50 rounds to determine what charge weight works best with my S&W686 & components.

I loaded 10 rounds for each weight of powder, starting at 10% below max and going up to max (5 different charge weights).

I was wondering what most of y'all did as to groups:
1 fouling shot, 3 groups of 3
2 groups of 5
1 group of ten
Something else?

I intend to find the powder charge(s) with the tightest grouping and then iterate again, dividing the range up into 5 charge weights. I hope I'll have a good load tuned to my S&W at that point.

Last: do y'all clean the bore between groups? I will start with a really clean, copper-free bore.

Thanks for your input.

 

[Sam Adams]

The thing that I like to concentrate on is consistency. What you are trying to do is to isolate individual factors like type of powder, powder weight, bullet weight, bullet shape, case length, etc., so that you can see how each does by itself. You toss those that are less than the best. As such, I sort cases by manufacturer and trim them to the same length, etc. You can't be perfect in isolating the various factors, but you can probably reduce 95% of the effect of any one factor by being careful.

As to what I do at the range, I usually do one fouling shot, most often with a factory round or with a reload of a bullet that I know won't be so accurate (i.e. I don't like to waste a match bullet on a fouling shot).

After that, I almost always do groups of 5 at each powder weight. If I'm using more than one bullet type then I usually do those on a separate target, again with every group getting 5 shots. If I've already narrowed the range of the powder charge (i.e. this is my 2nd range session), then I might do 10 of each.

As to the barrel, I like to start with it clean (except for the fouling shot), and I generally won't clean it during the range session unless I have a major change. The reason for this is that you are only going to shoot for testing purposes from a clean barrel once, and never if you do the fouling shot. After you've developed your "perfect" load, you're going to probably make a pile of it and then work on yourself by practicing as much as possible. Cleaning after every round, or after every group of 5, takes the joy out of shooting. However, if you are a match shooter, such measures may be justified. Anyhow, my practice is to clean at the range for different powders, bullet weights or bullet types at the same weight (e.g. 168 SMK vs. 168 Hornady AMAX). Then I do a fouling shot for the new ammo.

I would be curious as to your results. I have a 586 (6-inch barrel), the blued version of what you have, but I haven't done any real load development with it. Please let me know which bullets, powders and primers you find to be the best combination. As it is, standard factory ammo is very accurate in my gun - S&W makes a fine product - but who can argue with better results?

 

[Mikul]

With handguns, I slowly shoot 20 rounds into a target at 30 feet. There's no fouling shot, just 20 rounds, but I always dry my bore before I shoot. Best group and feel (an inconsistent recoil pulse is bad) wins.

 

[dodgestdshift]

No fouling shots. Shoot three and compare group. Its impolite to fire a fouling shot when looking at a large buck.