I'll try to keep the question short but give necessary information. I have been working on a load for a 6.5-300 WSM recently with a 29 inch Broughton 9 twist barrel. Brass is Norma 300 WSM necked down with a reading die and started with 140 Hybrids .015 off the lands and RL25. The rifle shoots really well, normally 1/2 moa @100 but extreme spreads are kicking my ass. For example one 3 shot group had a ES of just 2 fps so I loaded the exact same to the kernel on my FX 120i and shot another 3 shot group and got 30 fps. Last week tried Retumbo and on two different strings of fire the first 2 shots were identical velocity but the 3rd was 20fps higher, again loaded to the kernel. So, I need some ideas. Is this a neck tension issue possibly or do I need to try a powder like H1000 which locally I haven't been able to find or any other ideas.
ES variations
- Thread starter t_brooks
- Start date
You yourself may be able to tell while seating a bullet if the seating force is identical. If not, load more and cull the ones that feel good and test.
One other thing, blasting 65gr of powder generates a fair amount of heat, are you baking the 3rd rd in a warm chamber, or firing fast? Also, 3 shot strings is a terrible sample size for gathering chrono numbers, fire 10 and see, but close the bolt and fire, no need to aim to gather data.
One other thing, blasting 65gr of powder generates a fair amount of heat, are you baking the 3rd rd in a warm chamber, or firing fast? Also, 3 shot strings is a terrible sample size for gathering chrono numbers, fire 10 and see, but close the bolt and fire, no need to aim to gather data.
