by Rod_outbak » 23 Mar 2019, 4:44 pm
andym79,
I've not fired a slow-twist 7mm as you are thinking of building.
However, I have fired the 100gn Sierra HP projectiles.
I have a 7mm-08 Tikka T3 Hunter Stainless Fluted, with a 22.5" barrel, a 1:9.5" twist, and a 3-chamber muzzle-brake(Trentech).
Usually, I load 120Gn Vmax projectiles; I find they nail pretty much anything I aim at, and are very predicatable/accurate out to ~400 metres(about my limit anyway).
July last year, I got around to testing some 100gn Sierra HP loads, which I had made up 5 loads from 45.0gns AR2208, up to 45.5gns.
The 45.0gn loads produced 14mm groups at 100 metres. The other loads were larger groups than that.
Best guess is they were roughly around the 3100fps(another thing I intend to check up on when I re-visit this again)
I didnt get around to trying any loads below the 45gns, but I intend to follow up on this in the next 12 months.
For a hunting/carry rifle, I'm pretty happy with 14mm groups.
Good luck on your build.
Cheers,
Rod.
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