From: toby@stein3.u.washington.edu (Toby Bradshaw)
Subject: [RIFLE] [RELOADING] Load development
Organization: University of Washington

I was asked how I work up a load for a rifle without making a huge
factorial experiment (primers * powders * charge weight * bullet) out of
it, and without wearing out the barrel before "THE LOAD" is found.  Let
me say up front that I don't claim to have the perfect method, nor do I
conclude that other methods won't work.  This approach does work for me,
though.

A few preliminaries.  Everything is easier to interpret if you have an
accurate rifle (that is, a custom rifle built with top-quality components
by a knowledgeable riflesmith).  What we are doing with every shot is
putting a data point (distance from group center) into a hypothetical
analysis of variance (we could even use a real ANOVA, but I haven't gone
to that much trouble yet).  This ANOVA can include terms like primer make,
powder type, charge weight, bullet make, etc.  Tacked onto the end of the
ANOVA is the "noise" or "error" term, which includes all sorts of things
like aiming error; wind drift; accumulation of fouling; mechanical defects
in the rifle, scope, and ammunition; ammunition temperature;  friction on
the sandbags or other rest; the hold on the rifle; and so on.  To make the
analysis easier, we often assume that the components of the error term in
load development are random and normally distributed -- or even
nonexistent -- but they're not (does the wind blow in random directions
and at random velocity? -- no).  The bigger the error term relative to
shot displacement caused by the variables we're actually interested in,
like powder type and charge, the less informative is each shot.  An
accurate rifle will have a smaller error term because it's mechanically
sound -- the bedding doesn't change between shots, the breeching is the
same for each shot, powder and copper fouling do not accumulate as fast in
match quality barrels, etc.  So, contrary to what Todd Enders has said,
I believe that a small shot displacement with a very accurate rifle is MORE
informative than a larger displacement with a less accurate rifle, by the
ratio of their error variances.

So, a few rules of thumb.  Shooting without wind flags is waste of time if
there's any wind at all.  Wind drift is probably the biggest component of
the error term for most good shooters using good equipment.  For shooting
at 100 yards, 2 flags (at, say, 20 and 50 yards) are adequate.  For longer
ranges, use more flags.  Remember that the bullet is most affected by wind
close to the muzzle, since angular changes early in the bullet's flight
have a large effect on the point of impact downrange.  Doping the wind is
what separates the shooters from the trigger-pullers.

Shooting at 100 yards is a waste of time if the load will be used at
greater distances for accuracy shooting.  As we've seen from recent posts
by Bart and Henry, rather large deviations in muzzle velocity will have
relatively little effect on point of impact at 100 yards but are
disastrous at longer ranges.  Test at the longest range you intend to
shoot -- that's where accuracy really matters the most, anyhow.

Other than the barrel, which most shooters are reluctant to change, the
bullet is the most critical component for rifle accuracy (this assumes
decent bedding, high quality optics, good shooter technique, ability to
prepare decent brass and handloads, etc.).  Good bullets will shoot well
in any good barrel -- the precise matching of bullet to barrel has been
achieved at the highest levels of the shooting sports.  A factory barrel
is a pig-in-a-poke, but there's not a hell of a lot you can do about it
when choosing bullets since the vast majority of factory and handmade
bullets are very, very close to their nominal diameters.  "Fat" bullets
can be bought in the varmint calibers and might be worth some
experimentation in factory barrels if the standard diameters don't shoot
well.  If accuracy is the only goal, choose a bullet that is made for
target work.  There's no need to run out and buy a bunch of different
bullet brands and weights -- pick the weight that's matched to your
barrel twist and buy it from somebody or some company that makes
match-winning bullets.  If at all possible, buy handmade bullets.  Bullets
that perform well at short range will sometimes prove less accurate
at longer ranges -- another reason not to test at 100 yards when the
shooting will be at substantially longer ranges.

If we're talking about hunting, bullet selection is a little more
difficult.  You will often have to give up some accuracy for terminal
performance.  For varmint hunting I've had excellent luck with Nosler
Ballistic Tips, Speer TNTs, and Sierra Blitzes.  If you're shooting a
high-velocity .224 go ahead and shoot a match bullet.  They will blow
up much better in the big .224s than in the .222 class.  I shoot Bruno
52gr FBs in my factory .222, but they ricochet badly on small targets
(ground squirrels) at >100 yards or so.  For deer-sized game I like
Nosler Ballistic Tips and Sierra Match Kings.  I've used handmade .224s
on deer and antelope with good success, as well.  This requires careful
shot placement.

Once the bullet has been chosen with regard to barrel twist and intended
use (one MIGHT try a couple of bullets, perhaps a BT and FB), look for a
powder that is known to give good performance in that case with that
bullet weight.  Reloading manuals are a so-so source for this kind of
information.  Too many "lawyer loads" and unsubstantiated opinions are
the problem.  If the case is used in competitive shooting, and similar
bullet weights are used, find out what the top shooters are using and buy
a can of that.  Propellant choice is usually an easy decision, and I'd
never buy more than two powders when developing a load.  If the powder
fills the case, burns clean, and is easy to ignite (I prefer extruded
propellants for everything, myself), it will very probably shoot well.
Don't try to reinvent the wheel -- use what the top shooters have found
to work.

As for primers, there are only two I use, the Federal 205M and 210M.  The
210M will easily light extruded powders even in big cases like the .300
Wby, and produces much more uniform MVs in my experience.  If you're
using a big case (e.g. the Remington .308 basic brass) with a small rifle
primer pocket the Remington 7-1/2 is worth a try.

When working up a load, I first find the cartridge overall length (OAL)
that puts the bullet ogive at the origin of the rifling.  With custom
chamberings you should ask your gunsmith for a gauge made from a short
stub of barrel with the chambering reamer.  It will help you set your FL
sizing die, check neck thickness, and find the land contact point.
Second choice is the Sinclair tool or equivalent system.  A damn poor
third choice is smoking the bullet (or using a Magic Marker).  This
method is not very accurate because the bullet has to be well into the
lands to mark it.  The "cleaning rod down the barrel" method is useless
if an accurate measurement is wanted.

Now off to the range with all the cleaning equipment, wind flags,
reloading equipment (Wilson dies and arbor press are nice and portable),
targets, rests, etc.  You can preload at home, but you'll end up pulling
a lot of bullets or skipping a lot of testing.  There's so much variation
from day to day (or even within a day) that preloading is almost unheard
of in benchrest.

I set up three loads each with powder charges 1gr apart (2gr for big
cases) from the starting load to a few grains above maximum.  The initial
bullet seating depth is the land contact point.  I look for a load with no
vertical dispersion (<0.2MOA for benchrest rifles, usually close to
0.1MOA) at the range I'm shooting, that is still within reasonable
pressure limits (i.e. I can open the bolt without a cheater bar).  This
load will usually vary for each range, by the way.  Then I load 5 of those
and 5 of each 0.5gr on either side, and shoot groups.  By now I have a
feel for how well the thing will shoot.  Very often the most accurate load
is a hot one, just shy of blowing a primer, usually showing an extractor
mark, and above the maximum loads in the manual.  This is fine for
load-at-the-range target work, but a bad idea for a varmint load that may
be used when ambient temperatures are much higher than the testing
session.  Use your good judgement.  Some fine tuning of charge weight is
then done, followed by some seating depth fiddling if necessary (not
usually).  Remember that with this few shots I can't tell a .5" group from
a 1" group with any confidence (shooting at 300 yards, for me).  If
there's no vertical in the group, it's a rare thing for the horizontal
dispersion to be anything other than wind or bad technique (assuming good
bedding, no excessive fouling, etc.).  Vertical can also be caused by bad
rests and bad technique, and by strong head and tail winds or contour in
the terrain (berms, etc.).  The only way to tell what's happening is to
have a good rifle (then it's never the rifle that's at fault) or a good
shooter (then it's never the shooter that's at fault) -- preferably both
:)

You can chronograph your most accurate load and see if it is up to
expectations.  With the smaller capacity cases you will often be at or
above maximum listed velocities.  With the bigger cases (in a given
caliber) the best accuracy is often found at lower-than-maximum
velocity.  Decide what's most important.  Note that bullets leaving at
3500+fps tend to copper foul, and unless you clean during testing (and
varmint hunting) you'll spend more time measuring the effects of copper
fouling than the load performance.

I use a powder measure with a micrometer drum to allow quick changes of
charge weight at the range.  These are great for ball powder and short
stick powders, but only the best measures (like the Jones) will work well
with long stick powders.

IMHO, too many shooters head to the range with preloaded ammo, pop a few
caps, measure the extreme spread of each group, then choose "THE LOAD"
based on what amounts to no information (from a statistical standpoint).
Each extreme spread is one data point, with no estimate of the error term
possible (even though the error may be as big or bigger than the variance
due to to component changes).  Often the rifle has not been properly bedded,
no wind flags are used, the scope is of questionable quality, the trigger
needs a come-along attached to it, the rifle is never held the same way
for two consecutive shots, the handloads were prepared in mediocre dies or
with bad brass, the rests are abysmally poor, etc.  The error term in the
mythical ANOVA is now so large that you'd have to shoot a hundred groups
with *each load* to make any sense of it.  For many folks, maximum
accuracy just doesn't seem to matter enough to go to the trouble it takes
to get everything exactly right for load testing.  The actual "load
development" at the range takes a small fraction of the "preparation time"
that precedes the actual shoooting.  If you haven't done the background
work with quality equipment and components, you're not "testing", you're
just sending lead downrange and drawing incorrect conclusions from the
results.

-Toby Bradshaw
toby@u.washington.edu

From: toby@stein1.u.washington.edu (Toby Bradshaw)
Subject: Re: [RIFLE] [RELOADING] Load development
Organization: University of Washington, Seattle

In article <9311291823.AA24066@warp6.cs.misu.nodak.edu>,
Todd Enders A262 857-3018 <enders@warp6.cs.misu.NoDak.edu> wrote:
#
#toby@stein3.u.washington.edu (Toby Bradshaw) writes:
#
##Now off to the range with all the cleaning equipment, wind flags,
##reloading equipment (Wilson dies and arbor press are nice and portable),
##targets, rests, etc.  You can preload at home, but you'll end up pulling
##a lot of bullets or skipping a lot of testing.  There's so much variation
##from day to day (or even within a day) that preloading is almost unheard
##of in benchrest.
##
#     I don't quite understand the assertion that "you can pre-load at home,
#but you'll end up pulling a lot of bullets or skipping a lot of testing."

Because if you follow the loading manual, you'll have the "maximum
loads" made up in advance.  However, as you're shooting you find that
the groups are getting smaller, and no signs of excess pressure are
evident at the book "maximum".  There you sit, not knowing if an extra
grain or two of powder would halve your groups, and all your loading
equipment is at home.  The alternate scenario is that you run the
preloaded ammo considerably above the max book load, only to find
that the maximum *in your rifle* is two grains below that.  Now you
get to pull bullets.  To test lots of loads by preloading requires
a good deal of match-quality brass (if you want to shoot match-quality
groups, anyway).  Most people can't produce enough really good brass
to allow preloading.  I've used 32 cases in my 6PPC for the past two
years, and they're still going strong (not recommended for prairie
dog towns, though :)

#For benchrest, I can see the wisdom in loading at the range, but have to
#wonder in the case of highpower match rifles or hunting rifles where one is
#by necessity carrying pre-loaded ammo.  It would seem (to me, at least) that
#one would want to duplicate the conditions the ammo would be used under as
#closely as possible.

I agree.  It's pretty hard to do that if you load in the winter in
Seattle for gopher busting in Montana in the summer.  I preload for
all my hunting and varmint rifles.  You give up the nth degree of
accuracy, but as you note later, what's the difference in the field?
There IS a difference -- it's just a matter of whether it's worth it
to you.

#     Minimal vertical dispersion looks to be a good selection criterion.
#However, this method of making the initial isolation pass seems to me to be
#only slightly less arbitrary than selecting by "smallest group".

Not really, though it does suffer from sampling error because of the small
number of shots I usually use.  In decent conditions, my 2 sighter shots
touch each other about half the time at 300 yards, so I have a good deal
of confidence that the rifle is "honest".  Anyhow, measure some test
groups.  If they're consistently bigger horizontally than vertically, it's
not a load problem (as a rule).  If most of the groups have their largest
dimension vertically, the load may be at fault (assuming good rests, and
all the other "mechanicals" are in top shape).  The absolute group size
is an amalgamation of lots of factors -- the load can't usually fix problems
with horizontal stringing, so why measure it during testing?

#Aside from
#shooting at range and using a somewhat different selection criterion, this
#looks remarkably like how most people do "load evaluation" at 100 yds, for the
#first pass at least.  The more obvious difference is that they stop after the
#first pass, as a rule, and don't proceed to refine things.

Thus the sample size remains small and the results inconclusive.

#The headwind/tailwind component should be
#at least somewhat obvious from the wind flags, though.

They are.  If I had a buck for every "load tester" I've seen at the
range with wind flags, I'd still be poor, though.

#     The assessment that "For many folks, maximum accuracy doesn't matter
#enough to go to the trouble it takes to get everything exactly right for
#load testing." is, no doubt, true.  However, few folks actually *need*
#maximum accuracy in the first place.

That's why gas guns were invented :)

#Aside from the stool shooters, long-
#range target riflemen, and some fraction of varmint shooters, who else *needs*
#groups smaller than 0.25 moa?  0.5 moa?  even 1 moa?

Well, the groups you mentioned are everybody I shoot with :)  Accuracy is
ALWAYS a plus -- because you learn more from your misses, and there are
fewer misses to start with.  When I'm varminting and I miss a PD in
a howling Montana wind, I want to know that the distance I missed by is
an acccurate reflection of the prevailing condition, so that when I
hold off for the next shot I know where it's going.  "Area fire" just
doesn't appeal to me :)

#If they don't need it,
#in most cases they won't go the extra distance for a better barrel/trigger/
#stock/dies/brass/case prep/components/scope/etc./etc.

Not news to me.  Of course, many of these same people will bend your ear
telling you how accurate their rifle is, when they have no concept of
what rifle accuracy can be.  If you haven't had lobster, hot dogs seem
pretty good :)

#I'm not criticizing
#you or anyone else here.  You have an obvious need for extreme accuracy,
#and the loading method outlined above works quite well for you.  Those whose
#accuracy needs are less stringent will use less stringent methods in load
#evaluation.

Since the shots are already on paper, it doesn't make sense to me to
mis-handle some of the data.  For example, why measure extreme spread
or horizontal spread when evaluating a load when the load doesn't
directly affect anything but vertical?  Most people are "less stringent"
because of ignorance, not because they can't understand the concepts.
Frankly, many people can't evaluate loads because the load isn't
the limiting factor.  As soon as the "other variables" swamp the load
variables in magnitude, testing requires BIG sample sizes for validity.
The quickest way to find this out is to shoot the SAME load for about
10 groups of 5 shots, and then try to convince yourself that fine
discrimination is possible based on just one such group.  This opened
my eyes!

#By the standards you have to work to, their methodologies appear
#less than optimum, but these methodologies work for them, and they have
#greater confidence in their ammunition and firearm as a result.  There is
#nothing wrong with that, even though the ammunition/rifle are not as accurate
#as they *could* be.

It's wrong if their confidence is misplaced, and if simple procedures
could extract more useful information from the same number of shots.
Nothing as simple as the method I've outlined is going to be true in
all cases, but the "idiosyncrasies" of individual rifles are largely
mythical when top equipment is used.  Once factory rifles are brought
to the point where only their barrel is limiting, they are usually
pretty predictable, too.

-Toby Bradshaw
toby@u.washington.edu

From: toby@stein1.u.washington.edu (Toby Bradshaw)
Subject: Re: [RIFLE] [RELOADING] Load development
Organization: University of Washington, Seattle

In article <9311301744.AA14131@warp6.cs.misu.nodak.edu>,
Todd Enders A262 857-3018 <enders@warp6.cs.misu.NoDak.edu> wrote:
#
#toby@stein1.u.washington.edu (Toby Bradshaw) writes:
#     One disadvantage I can see to loading at the range involves the necessity
#of a scale to check/calibrate one's powder measure.  Of course, if one has a
#good benchrest measure that will easily repeat settings, this is rather a moot
#point, as long as one has a calibration chart for the powder being used.  On
#the other hand, the poor soul with a Lyman #55 is really going to have to
#transport his scale with him.  As a powder scale is something of a delicate
#instrument, I'd just as soon not have it at the shooting bench, where it
#might get knocked off, etc.

#     As a compromise, how about partial pre-loading?  (i.e. cases primed and
#charged with powder, but no bullet seated)  Yes, one would have to take
#precautions to keep the powder in the cases during transport, but other than
#that, I can't see any disadvantage.

You can bring pre-weighed powder in vials to the range.  Personally, I
prefer to have a decent powder measure.  I haven't used a powder scale
in a long, long time for accuracy shooting.  I haven't seen a scale at
a benchrest match on more than one or two occasions.

#     Certainly accuracy is a plus.  No disagreement there.  However, accuracy
#is an exercise in "diminishing" returns, if you will.  There are relatively
#easy things people can do to their firearms that will make them shoot better.

Why don't many people do them, then?  The trouble is (IMO) that many
people are spending their money on the wrong end of things.  They'll pay
an extra $150 for a varmint rifle with a flimsy plastic stock with an
aluminum bedding block when for less money you could buy the wood stock
version, have it professionally bedded (costs 10 times as much as doing it
yourself, but is still cheaper than the synthetic stock), and it will shoot
better than the unbedded synthetic-stocked version!  Why do people put up
with a gritty, creepy, 6-pound trigger pull in a varmint rifle (or any
rifle)?  Why do people pay good money for a bullet seater die that
can't produce decent ammo when for the same money he/she could buy a
Wilson seater?  Why do people spend lots of money loading ammo to
test, then shoot it downrange without a $2 wind flag to tell them when
to pull the trigger?

#There are things one can do in reloading their ammo that will make a rifle
#shoot better.

True.  It's amazing how seldom they're done.  The same guy who will
dribble powder one grain at a time will have a box of bullets that
came out of four different dies at the factory.  Guess which makes
more difference.

#The easy things will get you down inside 1 moa in most cases,
#and *maybe* close to 0.5 moa.  Now, from this point (the easy stuff being
#done), the things that one does to refine things don't individually gain
#a whole lot as far as shrinking the groups goes.  Primer selection buys you
#a bit, deburring flash holes gets another couple thousandths, uniforming
#primer pockets might get a tiny bit more, grouping cases by weight a little
#more, etc.  Of course, before one sees results from some of those techinques,
#one needs a better barrel, their action squared, etc.  The curve becomes
#pretty steep once one wants/needs to get below 0.25 moa consistently.

To get below .25 MOA consistently requires one thing only -- money.  For
the price of a benchrest rifle ANY competent BR gunsmith can put such a
rifle in your hands, and tell you the load to use.  If you can hold the
rifle correctly, and pull the trigger in some kind of harmony with the
wind, the rifle will put them all under 0.200" at 100 yards, every time.
You can tinker till the cows come home on many a mass-produced factory rifle
and never shoot a *single* group under 0.250"; certainly I've never seen
one that would *average* 0.250" at 100 yards for 5 5-shot groups.

#The
#individual has to decide how much refinement is enough for their purposes.

As long as it's an informed decision, sure.  I see a lot of misinformation
leading to disappointment.

-Toby Bradshaw
 toby@u.washington.edu

From: toby@u.washington.edu (Toby Bradshaw)
Subject: [RIFLE] Load development in a benchrest rifle
Organization: University of Washington, Seattle

A few months ago there was a thread on load development and testing for
accuracy shooting in rifles, and I offered a method that has worked for me
in benchrest shooting.  Since I just finished putting together a new light
varmint/sporter for the upcoming benchrest season, I thought I'd describe
how I "worked up a load"  for competitive shooting.  The main take-home
lesson remains that good equipment is very forgiving, and "load
development" in accuracy shooting is not the time-consuming factorial
experiment that some would have you believe.

The key to successful load development is to start with the best possible
components, to eliminate as many sources of error as possible.  My new LV
rifle is based on a Stolle Panda with right bolt and left port for
shooting speed (as much as a single-shot bolt action can be considered
"fast" :).  If you haven't seen one, the Stolle action is made by George
Kelbly's in Ohio, and is a work of art.  The Panda weighs less than two
pounds yet has a flat bedding surface 1.5" wide and over 8" long, broken
only by the cutout for the trigger bracket (the trigger bracket allows
trigger R&R when the action is epoxied into the stock).  The action wears
a Hart 1-14 twist 6mm barrel 21" long with a "max heavy" varmint class
taper, about 0.950 at the muzzle, chambered for 6PPC with a .262 neck.
Jim Borden of Tunkhannock, PA did the smithing and it is top shelf.  I
used a Lee Six gripless stock, which is at least 10 oz.  lighter (the Six
stock I got weighed 18.5 oz. before filling and painting) than the
McMillan, but which needs quite a bit of filling and sanding compared to
the McMillan.  IMO, on a 10.5 pound rifle there's no point in giving up
barrel weight just to make the stock prep easier.  I bedded the action
then epoxied it in place after painting the stock, and put a Jewell
trigger underneath and a 36X Leupold in Kelbly rings on top.

I turned the necks on 25 Lapua .220 Russian cases after expanding the
necks to 6mm and running them through a Redding 6PPC FL die to set the
neck/shoulder junction back (no expander ball used, *ever*).  The Redding
die is impressive for its ability to size the brass to just maximum specs
for 6PPC.  It moves the shoulder back 0.001 below the minimum headspace,
which is perfect for BR rifles where the headspaces are set to 0.001 or
less above minimum (generally a "go + 0.001" is used as a "no-go" gauge).
The FL die is 0.262 in the neck so it doesn't touch the case neck after
turning.  I turned the necks to give 0.0004"  clearance with the 68gr
Bruno BT 7S ogive bullets I prefer.  This is a "fitted neck" and doesn't
require resizing after shooting.  Jim Borden (like most BR smiths) ships a
"neck gauge" with each rifle, which is just a barrel stub with the
chambering reamer run in about halfway up the shoulder.  Loaded rounds
must be a slip fit in the gauge to be safe, and the gauge is also very
handy for determining bullet seating depth at land contact (by dropping a
bullet in the gauge and measuring how deep it goes, then measuring the
length of a fireformed case resting against the shoulder of the gauge, it
is easy to set cartridge OAL to put the bullet right on the lands, then
record the stem setting on the Wilson die and you're set.; takes more time
to describe than to do :).  The Lapua brass is the best brass of any kind
I've ever seen -- incredibly uniform in all dimensions and *none* running
out more than 0.001 at the head.  They're a buck apiece but there are no
culls to speak of.  They hold quite a bit more powder than the SAKO USA
PPC cases, and are very much like the original SAKO .220 Russian cases.
Naturally the primer pockets were cut to uniform depth (only touched the
corners on the Lapua brass -- even the primer pocket depths are *exactly*
on spec in this brass as delivered) and the flash holes de-burred (no burr
on *any* of the cases -- amazing stuff).  I use Federal 205M primers, like
every other BR shooter in the world.

I use 70gr Nosler Ballistic Tips for fireforming, but any boattail bullet
will do.  Flat base bullets won't go into the chamber with the neck cut
for boattails, because FB bullets have a pressure ring on the base.  So,
off to the range with the powder measure, Wilson dies, arbor press, and
about 150 pounds of other crap like front and rear rests, wind flags, ...

After boresighting, I fireformed the brass with 26gr of Australian H322
with the Noslers seated 0.010 into lands to keep the case head against the
boltface.  The expansion ring that is typically seen above the solid head
upon fireforming is generally absent in PPCs because the case
manufacturers make the cases close to maximum and the chambers are
minimum.  I ran a couple of patches soaked with Shooter's Choice through
the barrel after the first couple of shots to see how much fouling was
accumulating.  As usual for BR-quality barrels, fouling was minimal.  I
don't follow any elaborate barrel break-in because I've found it
unnecessary.  Just blast some fireforming loads downrange and clean with
Shooter's Choice every few shots, using a brush after perhaps 10 shots.  I
use a Mike Lucas bore guide (the best bore guide I've ever seen) and a
Parker-Hale rod.  I zeroed the scope with the first few shots then shot 20
Noslers at the same target, not really aiming carefully since I was just
fireforming.  The 20 shots formed a round group 0.402" high and 0.380"
wide at 100 yards, so I figured there weren't any major problems.  The
chronograph only showed about 2950fps for this load, which is way too slow
for the 6PPC.  I usually shoot the 68gr Bruno bullets around 3250fps.  So,
I cleaned the case necks inside and out, deprimed them, and primed them
again.  I loaded 5 rounds each at 28, 28.25, and 28.5gr H322 with the 68gr
Brunos.  I put in 6 clicks up elevation on the scope and went to the 200
yard target.  It was windy and I was in a hurry, so I just sent them
downrage looking for a load without much vertical dispersion.  The hottest
load looked best, with about 0.500" of vertical and 0.750" horizontal.
The usual pattern for load development is to put the bullet on the lands,
then increase the powder charge until vertical dispersion is minimal.
This must be done at longer ranges, like 200-300 yards, to be very useful
since even loads with lots of variation in muzzle velocity will group
decently at 100 yards for reasons that have been discussed in this
newsgroup many times.  Beyond the point of "minimum vertical", the groups
will open up all over from the excess pressure and eventually a primer
will blow.  In benchrest rifles in general, and in the Stolle action
particularly, there aren't a lot of pressure signs to look at until the
primer falls out of the case.  The Stolle (unlike some other BR actions)
doesn't have an ejector, so there's no place for brass to flow under
pressure to give you a sticky bolt lift.  Even the small flash hole on the
PPC case prevents extreme pressure signs from showing up early on the
primer.  All loads I've used successfully in the 6PPC caused significant
primer cratering, but case life is still very good (>50 reloadings, and
still going strong).  By this time I had to leave the range, but the next
week I returned on a rainy but intermittently calm day to find a load for
the 300 yard matches I shoot each month.  I started with the 28.5gr H322
that looked OK at 200 yards and loaded additional rounds of 28.8 and
30.1gr.  At 300 yards, the 28.5gr load had 4 shots with only 0.124 of
vertical, and 0.601 horizontal, but one of the 5 shots was up 0.713 from
the other 4.  The 5 shots with 27.8gr H322 had 0.815 vertical, and at
30.1gr the group was blowing apart from too much pressure.  I then loaded
10 each of 28.5 and 28.9gr.  The flags were hanging straight down when I
started the next group at 28.5gr.  The 5 shots were 0.752 high and only
0.259 wide.  I immediately went to the adjacent target with the 28.9gr
load, and the 5 shots made a no-wind group of 0.365 high and 0.186 wide.
Four of these shots were in a 0.107 bughole.  Not bad for a 10.5 pound
rifle at 300 yards!  The wind picked up a bit and I went back to the two
loads for another pair of groups to verify that the 28.9gr load is
suitable for competition at 300 yards.  The 28.5gr load again had 0.716
vertical, and the 28.9 was very flat at 0.290.  Note that *any* of these
loads is shooting reasonably well considering the distance, and *proving*
that two loads are different requires a lot of shooting and measuring (a
lot more than I did this time, or than I ever do).

So, in a couple of range sessions with 70 or 80 rounds fired (including
fireforming) I'm set for a season of BR shooting out to 300 yards.  The
load will have to be reduced in hot weather (usually about 0.1gr for every
10 degrees F), but by starting with a good rifle, excellent reloading
components and tools, and by paying attention to the only variable the
load can really help you with (vertical dispersion), my time at the range
is spent productively.  Compare this with the "factorial experiment" of
varying powder types, charge weights, bullet makes/types/weights/lot
numbers, primers, seating depths, _ad nauseum_.  In looking at the
equipment lists from major BR shoots note that only a few barrelmakers,
bulletmakers, powders, and cases are used.  There's a reason for that!
Don't reinvent the wheel -- the same components and loads that work well
for others will work well for you in similar equipment.  The same thing
can be said of factory rifles, except that accuracy levels are lower and
compromises have to be made in bullet selection.  Good bullets and good
brass will still make a big difference though, assuming your bench
technique and wind doping are not the major contributors to group
enlargement.

Good equipment is very tolerant of mistakes, so I need the best equipment
possible to cover up my many and varied boo-boos.  If you like accurate
rifles but you've never had the pleasure of shooting real benchrest
equipment, make a point of going to a BR match and try to find somebody
who'll let you pop a few caps in their rifle.  You'll probably have to be
pried loose!

Toby Bradshaw -- Biochemistry SJ-70 -- toby@u.washington.edu

Banning guns to prevent murder is like banning soccer to prevent riots.