Thanks,

Monte

If I get serious about a hunting load development I will shoot a series of loads with 1% (or even 0.5%) increases in powder charge over a chrono without moving the sights. I usually shoot groups of three shots to save time and money. I start at magazine length - .020.

I then plot the center of each of the groups in sequence on an x-y chart; a plot of average group size vs charge; a plot of average velocity vs charge; a plot of SD vs charge; and a plot of delta velocity vs charge.

I then look for places where 1) the groups are small, 2) the change in Point of Impact is small for small powder charge changes, 3)the velocity is reasonable 4) the SD is small and 5) the delta V per incremental change in charge is small.

If you have a well-behaved rifle and bullet you can actually satisfy all five criteria. If you get the first three you are usually good to go hunting with confidence using that load under varying weather conditions for years.

I have seen Audette attributed with basing decisions primarily on 2 and 5, I think. If you are a long-range shooter then 5 starts to become more important, but inside 350 yards I like my order of priority.

Don

Believe it or not, some loads will group at a lower MOA at longer range than they will at shorter range.

The reason, aside from the tendency of some bullets to "wobble" or "yaw" (like a football when it is first thrown which then stabilizes)--is this:

A bullet which has a lower velocity will of course be in the bore longer than one with a higher velocity. This extends the length of time in the recoil arc, thereby causing the bullet to print *higher* on the target at 100 yards than a faster bullet, which left the muzzle at a lower point in the recoil arc.

At longer ranges, however, something interesting happens. The faster bullet has a flatter trajectory than the slower one does. So these effects can cancel each other out. The slow bullet was at a higher point at 100 yards than the fast one, but since the slow bullet drops faster, it can actually hit a distant target in the same place as the fast one!

Audette did his tests at 300 yards, with only one cartridge per charge weight variation. He looked for a cluster in what was ideally a vertical string of bullet strikes on the target. He plotted (on a duplicate target next to him) the position where each charge weight struck. This probably worked well for some rifles and recipes, and not so well for others.

The method has fallen out of favor over the years, probably because it was troublesome to use and perhaps unreliable.

In my thread "new approach to load development" I have a tentative plan for a system which may work better. I'm hoping to have some folks try it out, and report their results.

I should mention that I have received an encouraging email from a reputable bullet manufacturer, who told me that I was going in the right direction with this idea.

I didn't invent the method, only my individual way of executing the method. The man who emailed me told me that he had been developing his loads in a similar manner for a long time. He also mentioned that adjusting powder charges (instead of OAL) was a waste of time and material in the search for a good load.

check out this link http://gscustom.co.za/

Dan Newberry
green 788

[This message has been edited by green 788 (edited 03-29-2002).]

[This message has been edited by Don Martin29 (edited 03-29-2002).]

[This message has been edited by Don Martin29 (edited 03-29-2002).]