From: megatek!hollen@uunet.UU.NET (Dion Hollenbeck)
Newsgroups: rec.guns
Subject: Re: Working up an accurate load
Date: 12 Nov 92 14:56:17 GMT
Organization: Megatek Corporation, San Diego, California

#>>>> On 11 Nov 92 15:49:49 GMT, wrm@friskie.WPI.EDU (William Michalson) said:

Bill> For those of you seeking maximum accuracy in your handloads (for
Bill> example, in BR shooting) how do you go about determining the
Bill> correct powder/primer/ charge weight/bullet weight/seating
Bill> depth/etc in an efficient manner?  Does your approach differ
Bill> depending on the cartridge/firearm combo (ie rifle caliber in
Bill> pistol, pistol caliber in rifle, small rifle, magnum rifle,
Bill> etc)?

First, vary powder weight.  My measure when set to whole number
increments will throw about .7gr  per whole number.  I throw cases for
every whole number covering the entire range suggested in the loading
manuals.  Once I shoot this, I determine where the nodes of accuracy
are, and then around those whole numbers, I go to either side of those
accurate nodes and use 1/4 numbers on the powder measure.  I then
decide what is THE most accurate powder weight.

Second, keep powder weight constant, vary bullet seating depth.
Generally, I started out doing the powder variance with the bullet
right up against the rifling.  I slowly back the bullet out of the
rifling by .005" increments until I get down to the standard MAX
cartridge length as noted in the reloading manuals.  I decide which
depth is the most accurate.

You would have to go through the whole matrix again if you change
powder or primers.

Yes, my approach differs depending on the firearm.  With my benchrest
gun, I am continually making little changes and trying to get another
.05" smaller in my groups.  My smallest group to date is .199".  I
watch my chronograph like a hawk to see that the Standard Deviation
for a group is as low as possible.  I sort my brass by weight before
and after preparation and keep each case in a numbered slot in a
benchblock and track each case's performance individually to see if a
particular case varies respective to the other cases in the group when
I change powder weight, etc.  I have been "developing a load" for over
6 months now on my benchrest gun.  I only use the finest benchrest
bullets and primers and brass which costs about $1.50 per case.

For my AR-15, I loaded some once-fired military cases with bulk
Winchester 55gr FMJBT bullets and Winchester small rifle primers.
Threw powder in whole number increments.  Used completely standard
bullet seating depths.  Determined that two numbers were most accurate
(1" group at 100 yards, the others were as inaccurate as a 2" group,
standard USA ammo gave 3" groups).  Threw 1/4 number charges around
the two nodes of accuracy, picked the best one, and now I am ready to
make a couple of thousand rounds.  

You need to decide what the goal is.  For the benchrest gun, it is to
be as accurate as possible, with the goal to get under .1".  With the
AR15, it is to be able to hit a 1" target at 100 yards, good enough to
keep in the center of a forehead.  



-- 
Dion Hollenbeck       UUCP: {uunet, ucsd, sun}!megatek!hollen
                      INTERNET:            hollen@megatek.com
Megatek Corporation  9645 Scranton Rd.  San Diego, Ca.  92121