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243 FPS Question

Butleroutdoors

Private
Full Member
Minuteman
Jan 23, 2014
88
23
Kansas
Good Morning:

Need your ideas/thoughts on fps performance of 243 Winchester. On my sons Ruger American 243, which shoots about 3/4" at 100 (so very happy with the accuracy) the fps is significantly lower than book. Here is the data:

Reload: Rem Brass, Fed Match Primer, OAL 2.65, 33.0 gr Varget, 100 gr Hornady Interlock BTSP #2453

Hodgdon's Manual shows 100 GR. SPR BTSP Varget, 31.0 = 2674 fps and 33.7gr =2838 fps

Actuals (chrono, separate days, over last few months)
2568 fps, SD11
2581 fps, SD 18
2529 fps, SD 9


On my 22-250, 6mm, and 6.5cm, the actual fps is usually within 50 or so fps of Hodgdon's reloading manual. I can not figure out why there would be such a delta between book and actual. I would estimate the bullet should do ~2780 fps

I don't suspect the different between SPR BTSP (book data) and Hornady BTSP (actual reload) would cause that much difference...is it possibly I am at min OAL and not getting enough pressure? Any thoughts, ideas?