I really can't fathom how LR could ever be considered a suitable replacement for Varget. One of the HIGHEST temp sensitivities vs. one of the lowest...
Big SD, the first stones I turn over are neck tension, case fill ratio, and ignition.
A few things of note which I bring up whenever folks ask this particular question...
Big SD, the first stones I turn over are neck tension, case fill ratio, and ignition.
A few things of note which I bring up whenever folks ask this particular question...
- First, recognizing that ES for valid sample sets typically will be ~4-4.5x the SD, a 31fps SD likely corresponds to an ES of ~125-140fps. So we're talking about potential for a LOT more than just 31fps shift in the ballistic engine. We may not realize all of that potential in our group, since we have other error factors within the group which do more to cancel each other than they do to compound, but our potential error is a LOT bigger than just the difference in drop calculated with 31fps difference.
- Elaborating that a bit: recall that SD is "Standard Deviation," meaning that ONE SD is the statistical expectation for any given shot to fall away from the arithmetic average. It's not a maximum, it's a STANDARD. We expect only ~2/3 of shots to fall within +/-1 SD above and below the average, with ~40% of those within +/-1/2 SD (~30% of shots between +/-1/2 and +/-1), and ~15% of those to fall outside of +/-1.5 SD - this means, for an SD of 31, we expect 4 out of 10 shots to fall within a 31fps span above and below the average (+/-15.5fps), and then expect 1 out of 10 shots, and ~50/50 to expect 2 out of 10 shots to be outside of ~46fps from the average... Pile that together and you're expecting one shot MORE than 46fps slow (or fast) and a bunch spread up to 31fps faster than average (or slower), so we expect to experience at least 77fps spread in a group, even when we trim off the outliers, knowing we should experience 125-140fps spread if we include the worst outliers.
- Tracking Varget in Dashers and H4350 in 6 Creeds, under 105's, every kernel accounts for ~1fps/kernel (.92-.97fps/kernel measured), with 62-64 kernels per grain. Experiencing an Extreme Spread of 125-140fps is around 135-150 kernels, which is equivalent to more than 2 FULL GRAINS of powder measurement error. Would you tolerate a powder drop or dispenser throwing charges so inaccurate that they were only +/- 1 FULL GRAIN?? I wouldn't, so I REALLY don't want to tolerate any other part of my handloading process which yields the same potential error.
- For folks who subscribe to the ideas of either velocity nodes or optimal barrel time, or really, ANY kind of node, can't ignore the fact nodes won't be 125-140fps wide, or 2 FULL GRAINS wide. Most of us are happy to see nodes 0.3-0.4grn wide, that's ~18-25 kernels, which is "deferred increase" of ~16-23fps... Do we expect a node to swallow a difference of 125-140fps?