two weeks ago i finally got my rum out for testing and im pretty excited as to how things went. my rifle is a sendero sfII with shilen trigger, de cheekpiece,de brake and bedded. it wear's badger max 50 rings and badger 20moa base with leupold mark4 4.5-14. here's how my first 100yd load development went. all loads were in new nosler brass with federal 215mag primers. only used h1000 and bullets were into the lands .005 with 210vld target match bullets. started powder charges at 88.0 and went up half grain incements all the way to 90.0. groups at the 88.0 grains started at 1.2 center to center and continued to shrink as charges got larger. at 89.0g i shot a .600 group and at 89.5g my friend shot a .400 group. 90.0g started to open back up to .775. wow i was more than excited. so i packed up and went home.
this last weekend i made up some more loads and took it to 200yds. i loaded the same length with powder charges increasing .2g increments. the groups were all consistantly double the size of the 100yd groups with corresponding charges. that is untill i hit 89.4g. all three holes measured 0.150... wow i've never shot that good even at 100yds. was it pure luck? hell i don't know. my velocities were within 15fps of each other.
i have now made up some loads for this weekend to try out 89.3,89.4,89.5,89.6 since this seems to be my hotspot at 100 and 200yds. the testing this weekend will be shot at 300yds.
Are you full lenght sizing your brass ? Or using a neck bushing if so what is the DIA .336,.337,.338 ? Looks like you found a great combo ,I have been using retumbo 87.5 still trying to tighten up my groups by seating . My groups are about 3/4 of and inch at 100 , I am getting 2840 FPS ave out of my loads ,
took her out to 300yds this weekend. 89.4 seem to be consitent 1/2 moa at 2980 to 3000fps. ordered 500 box of bullets then i'll be checking at 500yds plus. im really starting to enjoy this long range shooting more and more.
My recommendation would be to make larger jumps in powder charges. At 90grains a 1% increase would be .9grains. So round it up to 1grain incremental changes. Keep going up until you start to see signs of high pressure. Then start to dial it back from there.
Also, try Retumbo. It tends to provide great velocities over H1000.
FYI, my 300rum shoot 208grain Amax at 3150 with 91grains of Retumbo.
I'm not gonna shoot here. I'm gonna shoot waaaaaaaay over there!
1/2moa out of a factory 26" barrel is more than one could hope for. this is my 3rd trip out in load development starting with .5g jump stepping down to .2g increments now fine tuning to .1g. all my load development has created consistancy and accuracy at the same powder charge since the very first outing. i am not interested in max velocities or i would have built an allen mag.