.270 Win inconsistent velocity.
Hoping maybe EricBC can help out since you seem to know a good of amount about reloading:
I tried my chrony today about 10 feet away from my .270win and I'm getting inconsistent velocities for 53.5 grains (measured exactly on scale) of IMR4350, from 2750-2850 (I shot 90 rounds last week to see which charge gave best results, 53.5 seemed promising but now I'm second guessing the entire process). A fellow marksman told me IMR powder is inconsistent. He uses Hodgon's and claims no more than 20fps difference.
I am using Winchester brass (twice fired, neck sized with lee die) and CCI BR-2 benchrest primers, and Hornady 130gr SST.
I suspect brass to be inconsistent because new out of the bag 9 cases were bad. They vary in weight, and I guess they would also vary in volume, which may affect pressure, which affects speed. Some cases were also under the trim length and they haven't stretched after 2 firings (neck sized only).
If you were to take a wild guess, what would be the cause? I'm frustrated because I can't seem to get my tikka to shoot consistent good groups. Sometimes she shoots .5moa sometimes 2moa. Scope is Blackhawk 3-15x50FFP (Weaver made). Everything is tight on the rifle. I shot 90 rounds today and some groups were good, others not so good. What gives? The gun sits on rice bags up front and a squeeze bag under the butt. Trigger set to 2 lbs and I let her slide into my shoulder.
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