check your runout at both the neck and the bullet ogive. neck wall thickness, too.
I don't have one of these gauges yet. I know which one I want to purchase, just waiting for the money to pile up. Although the dies I'm using have the size bushing that coincides with my neck wall thickness. I'm also using Remington brass. I have a box of Lapua but I'm still perfecting my fireforming routine and I don't want to accidentally sacrifice any of it.
you don't mention the barrel... is it a punched out factory tube, or is it a custom? that alone makes a world of difference. trigger? scope? action work? stock?
It's a Cooper rifle, free floated bull barrel, two pound crisp trigger, Leupold 6.5-20X40mm scope and wood stock. No action work yet as I've only had the gun a few weeks. The rifle is guaranteed half inch at 100 and that's exactly what I'm getting. But....I know I can do better than that, I'm just unsure of the process to get there....hence my questions.
Have you tried different seating depths?
Yes, I have. With one powder/bullet/case combination, I found the amount of propellant that shot best then started playing with OAL. I started with the bullet at the lands and moved back in .005" increments. I usually shoot two groups and average out the group size to see which one is best. So far, the gun appears to like the bullets farther from the lands. With the Sierras, my tightest group was with cartridges with shorter OAL.
Bullets. Maybe sierra 69 bthp? Maybe some berger flat base?
The manufacturer specfies that with a 1-14" twist rate a maximum of a 50 grain bullet should be used. I have contemplated going to a 40 grain BlitzKing although the Bergers are on my short list of things to try.
In your shoes, I'd drop the charge 5%, and seat with the bullet 0.005" back from "jam length", then start groups at 0.005" further back, progressively. Once you find the seating depth it likes,then start increasing the charge.
Am I doing it incorrectly by varying propellant first? What is the reasoning behind OAL first, then charge weight?
The shooters rifle-handling skills are also approximately equal. most of the time, the winner will be the guy who read the conditions the best.
Sigh...I know nothing about reading the conditions. It sounds as if I better attend a match or two to learn me some stuff...
I am shooting the gun off a Sinclair windage adjustable rest with a rabbit ear rear bag. I don't think my goals are unreasonable but I was really stumped on what to do next. I just figured I'd start doing the bullet/propellant shuffle and mix and match components until something works.
Ed