Re: 260 Loads Only
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Short Round</div><div class="ubbcode-body"> If I was you (which I'm not ;-)) I'd take the brass from the last batch of firing with the ejector swipes and measure the neck thickness just to see if there is any serious variation. Secondly I'd weigh them with water in them and see if I could detect a volume difference between those with and those without the ejector swipes.
Tonight I'm playing with a new Sinclair premium neck turner and I'm playing with some remington .243 brass. I am getting some wide swings on neck thickness 0.0152" on one side and 0.0132 on the other is just one I noticed. Sounds like shitty brass and I suspect I'll find the same with my RP .260 brass. </div></div>
I just got done doing some measurements on two different charge weights.
First Charge 40.1 grains H4350
40.1 grains had no pressure signs and grouped well, but was only between 2672 - 2689 in 4 shots with a dirty barrel.
This load is normally around 2700 - 2710 with a clean barrel.
------ Grains -------- Neck
Case - Empty - Water - OD - ID
-- 1 - 167.0 - 222.3 - .298 - .266
-- 2 - 167.6 - 223.0 - .297 - .266
-- 3 - 167.4 - 222.7 - .298 - .266
-- 4 - 167.0 - 222.4 - .297 - .266
41.0 grains showed a little primer flattening and cases 2 & 3 showed ejector marks. Speeds were between 2726 - 2741 on four shots with a dirty barrel. This load is normally around 2740 - 2760 with a clean barrel.
------ Grains -------- Neck
Case - Empty - Water - OD - ID
-- 1 - 167.8 - 223.0 - .298 - .267
-- 2 - 168.0 - 223.2 - .298 - .266
-- 3 - 167.6 - 222.5 - .298 - .266
-- 4 - 167.8 - 222.6 - .298 - .267
I don't have a neck wall thickness gauge, so the outside diameter and inside diameter of the necks were taken with my digital calipers.
Nothing really sticks out to why I am seeing pressure signs with such a low charge and low chrono speeds.
I have my bullet jumping to the rifling (about .055 off the lands), so a jammed bullet shouldn't be causing the pressure signs.
I'm lost. I may just stay with 40.1 grains at around 2700 fps and call it good. I'd like to get around 2800 which would be about 2.5 less MOA at 1000 yards compared to 2700 fps.
As always, any help or direction is greatly appreciated.
Josh