Ken Campbell Iowa
13 February 2017
hi jim :: ... i am hanging on every word you report ... keep it up .
imho, you are already attaining about the ” accuracy ” level that a box stock rifle with a selection of 3 or 5 commercial molds might expect ... 2 to 3 inch 10 shot groups . so, in that respect ... you have arrived !! congratulations on a very useful load !!
i do know that looking through a 10+ power scope and watching bullets strike all around but not very near the crosshair is not that satisfying ... ha ... and now the fun begins ... the occasional tighter group will place that carrot just out of reach in front of your eyes ... but do enjoy the success you have reached so far, and by golly there very likely are some improvements to come .... hopefully they will benefit the rest of us, ...
especially we 6mm shooters .
breaking in the barrel ... mostly the barrel ahead of the throat will respond slightly to smoothing .... but the real need for break-in is the throat ... shooting 500 rounds will burn the burrs off the throat ... but will also burn the throat some ... so my ” model ” is to lap/polish the throat first thing with 280 grit ... my results range from * didn't need it * ... to * wow !! * .... a lead lap of the barrel is the best ... then you can get a feel for loose or tight spots down the barrel ... but again the improvement is mostly around the throat . you can also fire lap but only shoot 6 or 8 bullets ( jacketed is best ) with 280 grit .
ideally for cast you would use the 14 twist as do the mj benchresters ... however my opinion is that your 10 ? 9 ? twist is not the reason you get 3 inch not 1.5 inch groups, especially at 2000 fps; once you get to 1.5 groups you might start needing a 14 twist ( g ) ....
just some thoughts, keep on following your plan ....
oh, my worst loads .... big groups ... have been because of small noses under bore dia. ... they should engrave as much as you can chamber without causing varying seating depth ... hah another complexity .
thanks for the effort
ken, member, 6mm casters wannabees