Did some ladder work today working up a load for my 20" R700. I did the work at a shade under 300 yards, call it 290 or so. Using a CED M2 chrono with infrared screens. I used some Southwest 175 HPBT for reference and was getting 2450-2550 or so for a speed range on those in ft/s.
Worked my way up to max pressure for Reloader 15 using the 175 HPBT (or so says sierra) at 41.3 grains. This was using winchester brass, CCI 200 primers, and sierra 175 HPBT projectiles. Only wound up with an average velocity of 2233 ft/s with that setup across 5 shots. I'm at book max but something on the order of 200 ft/s and change lower than where I ought/would like to be.
Pressure signs, probably zero. No sticky bolt. Primers aren't cratered. Very faint ejector marks, which I have to elaborate on. I doubt I could even get it to show on a photo. I suspect I'm starting to get into the upper limits of the load but I also suspect I could add another grain or two before starting to see obvious pressure signs. I'm really putting these under a magnifying glass to see what I'm seeing now and it could just as easily be from running the bolt, its exceedingly faint.
I also got some brass mixed up and loaded these from 1x fired Southwest. Some of the southwest was showing some minor signs of overpressure in my rifle with cratered primers and a pretty noticeable ejector mark, but this is only a few cartridges in a case of 200. I think their stuff sits more along the lines of what my weapon can handle.
I found a nice accuracy load at 40.8 grains measuring a 4 shot group (1 flyer and it was my fault) coming in at 0.873 at 300 yards. That load is still supersonic at 1000 on my range per JBM. However, its like frickin 15 mils of elevation to get there when I get there with the southwest at about 10.5
Is that difference worth nitpicking over or should I say screw it, dial the extra elevation, and reap the accuracy?
I'm thinking about exploring the accurate load again, and I'm also thinking about going up over book max a half grain at a time and watching for pressure signs to see what happens. Would a different powder fair better?
Thanks for suffering through the rant if you're still reading!
Rich
Worked my way up to max pressure for Reloader 15 using the 175 HPBT (or so says sierra) at 41.3 grains. This was using winchester brass, CCI 200 primers, and sierra 175 HPBT projectiles. Only wound up with an average velocity of 2233 ft/s with that setup across 5 shots. I'm at book max but something on the order of 200 ft/s and change lower than where I ought/would like to be.
Pressure signs, probably zero. No sticky bolt. Primers aren't cratered. Very faint ejector marks, which I have to elaborate on. I doubt I could even get it to show on a photo. I suspect I'm starting to get into the upper limits of the load but I also suspect I could add another grain or two before starting to see obvious pressure signs. I'm really putting these under a magnifying glass to see what I'm seeing now and it could just as easily be from running the bolt, its exceedingly faint.
I also got some brass mixed up and loaded these from 1x fired Southwest. Some of the southwest was showing some minor signs of overpressure in my rifle with cratered primers and a pretty noticeable ejector mark, but this is only a few cartridges in a case of 200. I think their stuff sits more along the lines of what my weapon can handle.
I found a nice accuracy load at 40.8 grains measuring a 4 shot group (1 flyer and it was my fault) coming in at 0.873 at 300 yards. That load is still supersonic at 1000 on my range per JBM. However, its like frickin 15 mils of elevation to get there when I get there with the southwest at about 10.5
Is that difference worth nitpicking over or should I say screw it, dial the extra elevation, and reap the accuracy?
I'm thinking about exploring the accurate load again, and I'm also thinking about going up over book max a half grain at a time and watching for pressure signs to see what happens. Would a different powder fair better?
Thanks for suffering through the rant if you're still reading!
Rich
