guncollector wrote: |
For the first time I can remember, I chronied some new loads significantly faster than the reload books said they should go. I was loading for a new 338 RUM. I was expecting 3000 fps or so with a 250gr SGK and got more like 3300! Similar results with a 210 gr Barnes TS - about 10% higher than the book says. Shooting a Rem 700 SS 24 inch barrel. The only difference from the book loads were WLRM primers instead of Rem9.5. Seated 0.04 off the lands with the SGKs and 0.06 with the TS's. Thought it might be the Chrony so I tried a 8mm Mauser that I have previously chronied at about book velocities and it came in right where it should. Usually I find my results to be 5-10% slower than the load books. Anyone have similar experiences? |
guncollector wrote: |
Update - I went back to the range and stretched out the cable connecting my chrony to the readout as far as it would go. Probably 3 or 4 feet further than the last time. And suddenly the velocities dropped down to just about what the books say they should be. I think that there was enough muzzle blast reaching the chrony the first time around to make it appear that things were moving faster than reality. When I tried that 8mm load the first time as a check, it didn't have near as much muzzle blast so it was reading correctly. Lesson learned - larger calibers with larger muzzle blast must have more distance between the muzzle and the chrony to be accurate. |
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