A few years ago I did some initial testing of Powder Coating on cast boolits. Results of shooting test at that time was poor so I decided to abandon the effort for a time. Off and on I've followed the various threads on PC efforts, it seemed that there is a lot of focus on the technical aspects of applications and selections of products, but publishing actual results on paper is less so (with the exception of a few specific Forum members).
For this thread my efforts will be restricted to the RCBS 165 Sil boolit only. I had been following Bama's efforts in his thread: ACCURATE PC 350 Yds part 1. In that thread Bama focused on Nose sizing and other areas striving for a more concentric and accurate PC'd boolit. My efforts have not been as promising, but a start and some interesting data points.
All the following used Air Cooled RCBS 165 Cast boolits with a BHN of 9.8, cast from 96% lead, 3% antimony, and 1% Tin. Gas ch ecks were made from Ameri-max Aluminum flashing using a Pat Marlin GC die. Rifle is a Remington 700 Heavy Barrel Varmint in .308 Winchester. All testing Targets are at 100 Yards.
Group #1:
Boolit was used as cast. Gas Check was applied before HF Red Powder Coat was applied using shake and bake, one coat cured in oven at 400° temp for 30 Minutes, then Air Cooled. Sized to .310 in push through die. Nose measured ~ .304. Load was 45 Grains W760 in .308 Winchester. Group size for 8 shots was 2.481 MOA.
Attachment 185621
Group #2:
Boolit Nose was sized to .300 using an NOE nose sizer die. Gas Check was applied before HF Red Powder Coat was applied using shake and bake, one coat cured in oven at 400° temp for 30 Minutes, then Air Cooled. Sized to .310 in push through die. Nose measured .300. Load was 45 Grains W760 in .308 Winchester. Group size for 10 shots was 7.153 MOA.
Attachment 185622
Group #3:
Boolit Nose was sized to .301 using an NOE nose sizer die. Gas Check was applied before HF Red Powder Coat was applied using shake and bake, one coat cured in oven at 400° temp for 30 Minutes, then Air Cooled. Sized to .310 in push through die. Nose measured .301. Load was 45 Grains W760 in .308 Winchester. Group size for 10 shots was 6.837 MOA.
Attachment 185623
Group #4:
Boolit Nose was sized to .302 using an NOE nose sizer die. Gas Check was applied before HF Red Powder Coat was applied using shake and bake, one coat cured in oven at 400° temp for 30 Minutes, then Air Cooled. Sized to .310 in push through die. Nose measured .302. Load was 45 Grains W760 in .308 Winchester. Group size for 10 shots was 2.487 MOA.
Attachment 185624
The bore on this Remington 700 is .300.
Conventional wisdom says .001 over bore diamater (.301); yet it was the fatter nosed PC'd boolits (as cast .304 and .302 sized) that gave the best accuracy. I'll do some more on this at a later date.