Ok guys, shot a match last weekend, was doing OK, till one of the other shooters saw me using a cleaning patch to load, and gave me a strip of his patch material to try, when I tried it, the next three shots where stacked into a single elongated hole!
I took second in B-class. I Remember his face, but not his name, and didn't get to talk to him, but saved a piece, took it home, and miked it. It was a very soft pillow ticking. O18" very lightly lubed, with an oil, don't know what, but it wasn't greasy or slick at all. This prompted me to experiment, but had to limit the experimentation as I am running low on caps and can't find any to buy.
Am using a TC Hawken with GM 1:66" barrell. Rifling is .010-.012 as best I can measure. I have some .490 Speer swaged balls, and some .495 cast balls. I had some red pillow ticking that measures. 014" thick, and some blue ticking that measures. 022" thick. Lightly lubed each with 50/50 beeswax/olive oil. Fired five shot groups from the bench with sandbags at 50 yds using 50gr charge with each combo, here's the result:
It definitely shoots better tight. Help me understand why.
Calibre is 0.5" rifling is 0.01" on either side, so bore would be .500" land to land and0.520" groove to groove.
So:
(0.490" + 0.028")- 0.52" = -.002" loads easy with light thumb pressure, contact made with lands, not with grooves.
(0.495" + 0.028")-0.520 = 0.003" loads with stiff thumb pressure, only 0.003" compression against grooves.
(0.490 + 0.044)-0.520"= 0.014" required use of a short starter. 0.014" compression against the grooves
(0.495 + 0.044)-0.520" = 0.019" Required stiff hit on short starter, 0.019" compression against grooves.
Am currently searching for some ticking that Mike's an honest 0.018". And #11 caps!
Also noticed that each group has at least one flier at 01:00 O-clock.