Lowering ES 260 REM load

[Don A Parsons]

Yes,,, I use a charge master as well,,, but when I want the lowest of ES,,, each charge goes onto my custom 5-0-5 or my new 10-10 beam scale...

The idea of having it calibrated and tuned along with carbon powder on the V pillars really tightend up the ES,,, along with cleaning the Teflon V channels that the V pillars sit in... Quality scale could improve things in the ES department...

Ball mic the necks to 12 ot 13 thou keeping them all the same,,, pay attention to neck tension and you'll be off to the races.

Equal case volume,,, co-fax the length of your booltiz,,, CCI BR-2 primer,,, all this tightens ES...

Remember,,, a 1/2 gr of power """could""" add or subtract 4 ft-per seconds,,, this is not saying that it could be the same to 1 grain,,, each grain more or less in the mix will only incress this spread...

The best way for me to stay ahead of this is by measuring everything,,, pay attention to all the brass fore sure,,,

Lapua brass for me,,, and it all gets spec'ed,,, 2 boxes of boolitz of same lot as I check each boolit to sort them out,,, and seat those primers with the hand primer using your thumb... Just enough to get them flat on the base... Your thumb will have the best feel when seating primers... Ha

As posted above,,, watch the prime holes and inside the case to de-bur the spider Web in there... Oh,,,, and try not to run less than 87% less fill capacity,,,.old school golden rule with exceptions... My lowest ES are semi compact charges... Just me i guess...

You'll be golden once you get at it...

Good luck my friend...

Cheers from the North

 

[Don A Parsons]

PS: and thanks for the thread as I ran both of my weigh scales threw the 10 X's drop pan test...

My new to me 10-10 scale is off to the tuning shop since its showing signs of inconsistenty over the 10 drop pan readings...

Our weigh scales have to be spot on evey time if we want to lesson the ES variable...

As I mentioned along with others,,, everything has to be the same and consistant """if""" we want the lowest ES possible...

Not so much for my """close""" range hunting needs,,, but I sure start to see the groups opening up from the 600 to well past the 1200 metre mark...

I'm sure that all of do that is...

 

[Ghostmoney]

Finally was able to get out and do some more tests.
Decided to try lubing inside the case neck before seating bullet on the .010 load and shoot it again before changing anything to see if it would help the ES.
Shot in the afternoon with some moderate mirage, but shot a .26 group with ES 11
Also did some loads seated .015, .020, .030, .040, and .050 off the lands. .030 also was ES 11 but was 1" group. The rest of the loads were 26 and above for ES and around 1" groups

 

[Mike Thorn]

I would try another primer. A magnum primer might be an issue in the smaller case with a powder like H4350. I would try Federal 210 or even F210M if you have some.

Yep.
I'd definitely try a 210M primer. I had even better results using SRP Alpha brass and Rem 7 1/2's. 43.4gr H4350 with either primer was lights out though with the 130gr pills.