Ken tested a lot of bullets in the .224 but favored his 80 and 85 grain
designs.  The lighter weights just couldn’t withstand the rotational force or
velocities generated by the round.  They’d post big fps numbers but were
abysmal on accuracy and wind management.  Unsuited for 1:9 twist, they
also had to jump the throating required for the long 80’s.  Clark was
systematic in load tuning and without his tests we’d likely mistreat this
wildcat.  That insight may have been lost forever if not for Layne Simpson’s
article from the 1970’s.  It surely bridges the gap between Clark's set-up and
the round's potential with modern components.  Simpson’s results are as
follows and come from a 26” barrel:
Velocity (fps)
80 grain Clark
WW 785
80 grain Clark
H 870
85 grain Clark
H 570
85 grain Clark
H 870
85 grain Clark
IMR 4831
80 grain Hornady
H 870
80 grain Hornady
80 grain Hornady
H 4831
53 grain Hornady
WW 785
53 grain Hornady
The main difference between the 80 and 85 grain Clark bullet was five grains
more core and a thicker jacket.  That’s not to say the 80 was thin on copper
though.  Its exterior was much heavier than 22 bullets from that era.  
Earmarked for medium game, Ken even tried a 85 grain partition style for
controlled expansion.  I suspect it was hard to form and even harder to get
to shoot steadily.  He replaced it with the traditional lead-core, single-jacket
boat-tail we’ve all come to know and love.  

Ken built dozens of .224’s and shipped many to Texas where .22-caliber is
legal on deer.  Reports of bucks crumpling at 500+ yards soon abound as did
tales of string-line trajectory.  On varmints it was absolutely vaporizing.  
Where the .22-250 and Swift start to lay down at 400 yards the Clark is still
trucking.  I’ll cite trajectory figures later but for now think of the .224 at 600
yards like a .22-250 at 400.  With the right scope, prairie dogs were even
exploding at 1,000 paces.  That kind of hype and word of mouth must’ve
carried the cartridge because it got little to no formal press.  But without a
regular supply of bullets it would’ve become an overgrown Swift.  Clark
wisely offered his in bulk and eventually convinced Hornady to make the 80
grain.  For years this was a Clark exclusive, meaning you had to go through
Ken to get them.  They’ve since been cataloged as a low-drag A-Max.

Case forming can be involved depending on how you treat the neck.  One
pass through a FL sizer takes the Roberts to 22-caliber.  Fire-forming pushes
the shoulder out 10 degrees and the sidewalls by 0.0125” per. If you leave
the neck unaltered you’re done but Clark went further.  In an effort to
maximum accuracy he turned the necks to remove run-out.  So what’s run-
out and how common is it among factory brass?  Basically it is seen along
two dimensions: 1) Wall thickness, and 2) The shell’s centerline axis.   Neck
turning addresses the first and results in uniform purchase and consistent
bullet tension.  By doing so it also alleviates #2 but sizing technique is a
factor.  Most commercial brass exhibits 0.002” – 0.004” worth of run-out.  
Match-grade brands average 0.001” or less.  As illustrated:
The wall thickness varies from 0.0164” to 0.0132” or three-thousandths net.  
When neck sized, the die makes the outside diameter perfectly round.  The
trade off is it pushes the unevenness to the inside edge.  It’ll look like a
concentric circle but will be offset to the case centerline.  The bullet then
deviates from the bore axis and accuracy suffers.  But wait it gets better.  If
your FL sizer has an expander ball it may re-orient the neck on upstroke
(since the neck is already out of the die body).  Luckily most expanders have
a little float built into them so they self-align on the mouth.  If not it'll revert
to the initial 0.003” o.d. run-out.  Kinda like a dog chasing his tail isn’t it?
The solution is to uniform the wall thickness.  There are two ways to do this
and the first is the most common.  By turning the outside of the neck we're
able to remove the high spots and get precision within a few ten-thousandths.
You'll also notice we went 0.0005" more than the low figure of 0.0132”; most
folks do so to guarantee clean-up.  The second, and less prevalent method, is
inside reaming.  The problem with this technique is reamers want to follow the
hole.  They’ll cut 0.004” but that amount may be equally applied to the
sidewalls.  On the other hand, if a boring bar is used or the neck and case
body are held firm in a centering device you can inside ream.  No matter how
you get there, thinning brass will increase chamber clearance.  To circumvent
this I use finishing reamers matched to the turned diameter. I'll talk
specifically to the .224 Clark neck during load preparation.  Just understand
why Ken went to these lengths.
We started with a VZ 24 Mauser action I’ve had for over a decade.  Produced
in Czechoslovakia from 1924 to 1942, they’re considered one of the highest
quality pre-war 98’s. First-rate metallurgy, no rust or pitting was present, and
most of the original blue was intact.  As with all of our Mausers we began by
truing the main ring and facing the bolt.  Opening the recess and extractor
wasn’t necessary since the Roberts and 8mm share the same rim.  A simple
skim pass was made to even the surface.
The Mauser bolt was replaced with a homemade knurled handle.  These
photos illustrate the angle set, welding, and final shape (note - the last picture
was taken prior to weld filing and polishing)
Since the 1950’s 22-caliber twist rates have increased.  Clark was limited to
1:9” but nowadays Hart, Pac-Nor, Lilja, and Shilen machine 1:6"- 1:8".  I've
always had good luck with Shilen and they list a 7 and 8.  Conventional lands
or their ratchet rifling are available on the 1:8", standard only on the 1:7".
Ratchet cut isn't all that new, it merely entails canting one side of the land.  
Groove count also drops from 6 to 4 with the Shilen.  I’ve only used a ratchet
on one rifle and that was a flame-throwing .264 Magnum.  They’re supposed
to foul less and increase velocity due to a more graduated imprint on the
bullet.  Honestly, I couldn't tell much of a difference between the two.  But
then again my experience with them is singular.  I spoke with Shilen years
ago on the ratchet and was impressed with their answer.  They didn’t upsell
it.  Instead they said some believe the rifling fouls less.  No promises or hard-
set rules, just a very gracious offer: "Try it.  If you don't like how it performs
we'll send you a 6-groove"

I damn near ordered a ratchet but decided on 1:7” straight.  Berger’s 90
grain VLD is a bullet I’m eager to try and they recommend 1:6” – 1.7”.  
Three weeks after the phone call to Texas a match grade stainless 22-caliber
found my doorstep. No.5 contour, 30 inches in length.