safeshot wrote:Hi all,
I have been weighing the cartridges for my Lithgow 101 to shoot rim-fire bench-rest. I use SK "Red" or red devils as we call them.
I have seen gradually improved results. The ones that weigh differently to the majority of 51.4 grains those being 52.0 or 51.9 or 48.9 I put in a "warm up" box these i shoot my practice targets with to warm up the barell. So the rounds used in the detail are all the same weight.
I also go for a short walk between details to rest my eyes and drink water as well.
Comments
Are you sure your gradually improving results aren't a matter of gradually improving ability?
Do you weigh the fired brass afterwards to see how consistent they are?
CCI Quiet fired brass for example for me runs .9.92gn down to 9.82gn, or 1% variance.
I haven't pulled any match bullets but a sample of a dozen Remington Cyclone bullets give me a spread from 39.34gn up to 40.16gn, .82gn variance, but over four-times the weight, so 2% and not at all bad, even for crap ammo. Match-grade jacketed bullets generally have around a tenth of a grain weight variation at most. I don't seem to have kept the Cyclones charge weights but I do recall that they were astonishingly consistent. My scale reads to .02gn and I think they all weighed exactly the same. I've never tried weighing the primed cases, then firing and weighing each one to determine the consistency of priming compound, but I'd be surprised if there's any measurable difference there. As the bullets are dipped in lube which simply runs off under gravity, I doubt there's any measurable difference in that either.
I think manufacturers are well on top of weight consistency nowadays so I don't think there's any measurable gain to weighing match-grade .22LR ammo.
Measuring rim-thickness can see measurable improvement with cheaper ammo, but I doubt you'd see any difference with match-grade ammo. Cheap ammo can see up to about .010" variation in rim thickness (I even had a Winchester round that was so thick it wouldn't chamber). Match-grade ammo won't have any difference you can measure with a one-thou micrometer, and I doubt 2-thou is enough to make any difference between batches (I rim-thickness batched something like 12,000rds of 101 different types of ammo).
https://enoughgun.com/forum/viewtopic.php?f=12&t=13423I think all that's left, and which probably is the most important, is the bullet diameter, and consistency of shape.
Running your ammo through a die to swage the bullets up to a consistent diameter (trial and error to determine the diameter your rifle/ammo prefers) and shape is probably going to be the biggest improvement, but I don't think this would be legal for competition.