In preparation for a filed target match tomorrow, I have opened a new tin of JSB Exact Heavy 10.34 grain (.177 cal). These are nominally 4.52, and were purchased more than a year ago from Pyramyd Air, but previously unopened.
The protocol I recommend is to sample 10% of the tin, and thus I will gage 50 from this tin using the
Pelletgage.
This is what the tin looked like - there was no marking of head size, but it appears that
JSB only produces this pellet in a nominal 4.52 mm size.
https://goo.gl/photos/YtGQGQZGzwBBe72C6 https://goo.gl/photos/gXfTBogbPTBZeJxKA This JSB pellet has been my "go-to" for about two years worth of shooting. Usually, I go through some inspection when I open a tin, and once I have the sample result, I decide whether to use them. Even considering practice, a 500 piece tin will usually last me several months.
Of the 50, gaging resulted in 8 of 4.51, 41 of 4.52, and one at 4.53 mm. I consider this a good result. The mean was 4.529 and the sample standard deviation was 0.0040 mm. Statistically, this would mean that if we have a normal distribution, 95% of the tin would be within 4.529 +/- 0.008. This is the histogram.
https://goo.gl/photos/ZUviTQBuVsEaGT6E9 There were three pellets with skirts that were dinged, I did not include them in the sample.
One may say that this does not appear to be a normal distribution (i.e. skewed, perhaps affected by screening, etc.) - nevertheless, I consider this tin to be
very much usable, and I know from experience my Marauder (with Lothar Walther barrel) will do well with a 4.53 pellet - so this is practically as good as I hope to see as an inspection result. I have historically seen exactly one tin of this pellet where essentially all were gaged at 4.53 mm.
This also meets my basic quasi-statistical sampling plan - find the sample mean, and accept if no pellet is more than 0.01 mm from that mean.
For my field target match, I will screen more pellets to get 100 or so that will all be 4.53 mm. To be specific about the gaging, they will all be <4.53 and >4.52 mm.
I recommend this process for assuring that you have the pellet your gun "likes" best, and for minimizing the chances of a flyer. I also recommend this pellet as being very consistent and stable out to about 50 yds, with 19 FPE at the muzzle.
. Nice scale! The 12" LW barrel in my Talon SS will stack unsorted 18.13gr JSB Jumbo Heavy Diablos all day long in one ragged hole to cloverleafs at 25-35yrds with an occasional flyer usually attributed to a bad skirt. I just found through experimentation that the H&N Barracuda Hunter Extremes group just as well with same POI, but with a bit more smack-down. Despite their advertised weight of 19.09gr, they come in a little light ~18.8grs and their skirts seem a little more uniform and less fragile than the JSBs. I think my search is done for now, but would have never known without testing a variety..
