*My load may not be safe in your rifle and is slightly over a few different published maximums. For your own safety do not copy this load and use it.*
*Not asking anyone to give me a "new" charge weight*
Question:
Is it normal to lose this much velocity going from new (higher v) to once fired brass (lower v) for 300WM? Barrel had about 100 rounds on it before I did any of this, so if anything, I was expecting it to start speeding up a little between 100 and 200 rounds, not slow down. If it's expected that things slow down, is it due to a significant amount of case expansion (which I understand is expected in many belted magnums) and a subsequent drop in pressures?
Details:
Sako 85 in 300WM (edit: with factory barrel), setup and shot as a hunting rifle with factory barrel, not a target rifle.
Peterson "long" brass unfired, 75.2gr H4831SC, 180 TTSX, CCI LR Mag primers - good (enough for me) 3-5 shot groups consistently around 0.4-0.5" at 100. Chrono says 299x-300x fps - higher than I expected for a 24.4" barrel, but sure. Rifle shoots 1.5-2" plus 3 shot groups regardless of jump if I download to under 74.x gr or 2950 fps so I don't want to get it back under most published limits of 74.x. Groups tightened back up the closer I got to around 3000 fps. I didn't find a lower node for this barrel / projectile combo either - EDIT - apparently there was a node around 2825-2850 I dug out of some notes.
Go to once fired brass, same load, about the same amount of neck tension felt in the arbor press vs new brass. Chrono says 291x fps and groups open up to ~2" as expected. Try again at 75.4gr and still no pressure signs, velocity 2935-2940 now, groups shrink a little bit to ~1.5" as expected per previous results.
No pressure signs that I'm aware when I was working with new brass or afterwards with once fired brass - no hard bolt lift, flattened primers, crater in primer, weird recoil, etc. ejector marks not applicable on this action is it's functionally CRF.
edited for clarity
*Not asking anyone to give me a "new" charge weight*
Question:
Is it normal to lose this much velocity going from new (higher v) to once fired brass (lower v) for 300WM? Barrel had about 100 rounds on it before I did any of this, so if anything, I was expecting it to start speeding up a little between 100 and 200 rounds, not slow down. If it's expected that things slow down, is it due to a significant amount of case expansion (which I understand is expected in many belted magnums) and a subsequent drop in pressures?
Details:
Sako 85 in 300WM (edit: with factory barrel), setup and shot as a hunting rifle with factory barrel, not a target rifle.
Peterson "long" brass unfired, 75.2gr H4831SC, 180 TTSX, CCI LR Mag primers - good (enough for me) 3-5 shot groups consistently around 0.4-0.5" at 100. Chrono says 299x-300x fps - higher than I expected for a 24.4" barrel, but sure. Rifle shoots 1.5-2" plus 3 shot groups regardless of jump if I download to under 74.x gr or 2950 fps so I don't want to get it back under most published limits of 74.x. Groups tightened back up the closer I got to around 3000 fps. I didn't find a lower node for this barrel / projectile combo either - EDIT - apparently there was a node around 2825-2850 I dug out of some notes.
Go to once fired brass, same load, about the same amount of neck tension felt in the arbor press vs new brass. Chrono says 291x fps and groups open up to ~2" as expected. Try again at 75.4gr and still no pressure signs, velocity 2935-2940 now, groups shrink a little bit to ~1.5" as expected per previous results.
No pressure signs that I'm aware when I was working with new brass or afterwards with once fired brass - no hard bolt lift, flattened primers, crater in primer, weird recoil, etc. ejector marks not applicable on this action is it's functionally CRF.
edited for clarity
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