Here is a synopsis of my efforts to develop a match load for my 1898 Krag rifle (made in 1902).  The rifle is as issued except for a new barrel, made by Criterion, obtained through the CMP and installed by David Sams.

Previous threads (in chronological order):
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Tools:
Whidden Custom Die Set – neck bushing resizing die and micrometer seating die, custom made to match the resized brass to my chamber.
JLC Precision modified RCBS and Hornady neck bushing dies.
RCBS Pro Trimmer
RCBS 10-10 Beam Scale
Royal Resizing Wax (apply lightly, resize, wipe off)

Components:
Hornady 220 grain jacketed round nose
Once fired Remington brass (in my gun)
40 grains of IMR 4350, individually weighed on a RCBS beam scale
Remington 9.5 Large Rifle primers

Fired brass measurements:
a. Length at shoulder using a .375" collet - 1.784"
b. Neck dia. - .340"
c. Shoulder dia. - .422"
d. Gas ring dia. - .456"

Measurements after resizing with the RCBS and Hornady dies modified by  JLC Precision (James Carstensen) into bushing dies (both measured the same):
a. Length at shoulder using a .375" Sinclair collet - 1.782"
b. Neck dia. - .3325" (using .332” neck bushing)
c. Shoulder dia. - .420"
d. Gas ring dia. - .454" 

Runout of the cases after resizing with the JLC dies ranged from .000" - .002".  The runout increased slightly (~.001”) when I used the Whidden neck bushing die.

Conclusions:
a. I can’t conclusively attribute the improved performance to any one step in my process; however, once the best powder, charge weight and bullet was selected through the normal trial and error method, primer selection seemed to have a significant impact.
b. In my testing magnum primers induced far more vertical dispersion than did standard primers.
c. With my load Remington 9.5 standard primers virtually eliminated all vertical dispersion.  Further research on line verified that many competitors find Remington 9.5s give the best accuracy.
d. Keeping neck tension uniform at .002” provided the best combination of ruggedness (bullet stayed aligned in the cartridge throughout the loading and firing process), and uniformity (in terms of bullet release during the firing cycle).  This also helped eliminate vertical stringing.
e. Like using the wrong primer, crimping the case mouth induced excessive vertical stringing.  It complicated obtaining uniform neck tension.
f. The modified neck bushing resizing dies and micrometer seating die made to fit my particular case helped keep total runout to within very small tolerances.

When things go good, it's generally not one single thing, but the combination of all.  That's great for 200yd!  I'm going to be working with some lighter bullets, 130s & 150s and if I get a load that groups like yours, I'll be using them in the Roosevelt.  Actually, I have quite a few loaded, need to get to the range.

Here is an example of the distribution of runout on my loaded rounds.  I measure the runout in .0005" increments, each column being one .0005" increment.  Column one is less than .001", Column two between .001" and .0015", Column three between .0015" and .002", etc.  The largest runout was one at .0055".  I normally segregate in 100 round lots, but since I have almost 600 rounds to load, I think I'll segregate across the entire batch so that I have ~400 with runout less than .004" and the balance with higher runout numbers for practice.
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bote wrote on Apr 28^th, 2016 at 6:35pm:


Nope.  I just gave it a good cleaning.  Didn't refinish the stock either.  I just used hot Linseed oil and gave it a soak and a brisk scrub with an old T-shirt.
Keith