All of today's loads used the "partially Ardito'd" 40 BHN bevel base, sized 0.3575", and seated 0.009" away from contact. This is what I mean by "partially Ardito'd" -- it was intended to be a compromise between the good alignment of a tapered Ardito style bullet and the good gas sealing of a 1-diameter bullet.

Today's target. The numbers refer to the order in which they were shot.

#5 yesterday)
-- 17.2 gr WC297
-- 2006 fps
-- 0.87% standard deviation
-- 2.63 MOA
-- 0.77" mean radius
#1 today
-- increase powder to 17.4 gr. WC297
-- 1977 fps (slower than yesterday perhaps due to cooler temperatures)
-- 1.05% standard deviation
-- 2.15 MOA
-- 0.62" mean radius
#2)
-- increase powder to 17.7 gr. WC297
-- 1982 fps
-- 0.87% standard deviation
-- 3.2 MOA
-- 0.98" mean radius
#3)
-- return to 17.4 gr. WC 297 because that seemed to be the sweet spot
-- 1975 fps
-- 1.07% standard deviation
-- 2.19 MOA
-- 0.63" mean radius
#4)
-- same as above
-- 1997 fps
-- 1.06% standard deviation
-- 3.46 MOA
-- 0.97" mean radius
Conclusions and Observations:
-- these WC297 groups taken together averaged 2.73 MOA and 0.79" mean radius. Nothing to brag about, basically the same as the old Lil Gun load.

-- all of today's loads fouled slightly for 2" past the chamber. Most of the time a single dry patch would clean it up. A couple of times the dry patch had to be followed up by one wet patch. I never had to use the brush or any other "scrub-a-dub-dub" stuff. On the whole this load fouls about 50% less than the old "full Ardito" bullet with Lil Gun. Nonetheless I consider any significant fouling to be unacceptable because it may cause fliers.
-- I had abandoned WC297 a while back because it seemed prone to vertical stringing, but it appears that most of the vertical stringing can be eliminated by tweaking the powder charge.
-- Yet the fact remains that this "good" chamber is not as accurate or as clean as the original bad chamber, and I don't know why.

-- At the end of the day I fired the 17.4 gr. load into the water trap, and the bullet definitely yawed. It definitely was enough to cause a flier.

Things To Try Next Time
-- try the WC297 load with 25 BHN bullets rather than 40 BHN.
-- possibly try an "Intermediate Ardito" to improve alignment and reduce yawing.
-- check cases for wall runout that might cause the bullet to be off-center
-- possibly return to 0.359" diameter to ensure the bullet is centered in the chamber. I haven't noticed a difference in performance between 0.3575" and 0.359", though.
-- possibly try a card stock wad under the bullet.
-- shoot more bullets into the water trap to check for yaw, gas cutting, bevel melting, etc..