Re: 300 RUM with 210 BERGERS
Just an fyi, my 300RUM load with 210's and Retumbo (factory 26" barrel) is 94.7g at just under 3K acc'd to exbal using Litz's bc numbers, but about 3020fps with my chrono. It is very consistent.
Edit: Got called away and couldn't finish this post...
-.010 and ~3.845 OAL and FED 215M. Interesting that your 94g load grouped best and that's close to where I am. Might be a sweet spot with the RUM and 210's.
That ES is quite odd. What are your reloading techniques--close to or essentially benchrest techniques I'm guessing?
I'VE BEEN SHOOTING NBRSA SHORT RANGE BENCHREST MATCHES FOR 10 YEARS OR SO, SO I IMAGINE A LOT OF THAT BLEEDS OVER INTO ALL MY RELOADING. BUT WITH THE RUM, I BOUGHT REMINGTON BRASS, WEIGHED AND SORTED THE 100 CASES I BOUGHT INTO ROUGHLY TWO GROUPS AND CHAMFERED THE CASE MOUTHS, SLID A BULLET IN PLACE, MEASURED THE LOADED CASE NECK WITH A VERNIER CALIPER. I WAS REALLY SURPRISED TO FIND THAT THE CASE NECK THICKNESS VARIED LESS THAN A THOUSANDTH ALL THE WAY AROUND THE NECK ON THE CASES I CHECKED. I SPENT MORE TIME FUSSING WITH WHERE TO START WITH THE BULLET SEATING DEPTH THAN ANYTHING. I FINALLY SET THE BERGERS AT ABOUT .010 INTO THE LANDS AND LOADED THE CASES USING AN RCBS CHARGEMASTER.
I LET THE BARREL COOL WITH A WET TOWEL ON IT BETWEEN EACH GROUP FOR 5 TO 10 MINUTES BEFORE SHOOTING THE NEXT ONE.
I WAS SURPRISED AS ANYONE WHEN THE 92, 93 AND 94 GRAIN GROUPS COULD ALL BE PUT ON TOP OF EACH OTHER AND MEASURED LESS THAN 1/2 INCH. THE GROUPS ALL FORMED AT THE SAME STOP ON THE TARGET AND RESEMBLED EACH OTHER VERY MUCH IN SHAPE EXCEPT THE .175 GROUP LOOKED LIKE A 3-LEAF CLOVER WHERE THE OTHER TWO GROUPS HAD TWO BULLETS TOUCHING AND THEN ONE JUST A LITTLE OUT OF THE GROUP.
I'M GOING TO TRY THE 94-GRAIN LOAD AT 500 YARDS SOMETIME SOON AND SEE IF THE VERTICAL IS GOOD OR NOT.