Before I started sizing my CPLs using a home made sizer I found a few "practices".........

January 7 2018 at 3:41 PM

nced  (Login SpringerEd)

Response to Pellet sizing

that help with getting a relatively consistent pellet head measurement. While I'm not convinced that a digital or dial caliper will give a "precisely accurate" "metric second decimal point", however I have found that a proper sort procedure will be accurate enough for a consistent fit in the lead of the barrel, unlike pellets loaded directly from the tin or box. I'm of the opinion that as long as the pellet head is large enough to be "swaged a bit" when loading into the breech, "that silly little 1/100th of a millimeter" variation doesn't make much of a difference (if any) in the poi. The issue where a couple 100th of a mm makes a difference is when using loose fitting pellets where some are too small to be swaged to "leade size" when loading.

When I'm measuring pellet heads I follow these steps......
1. Start with a digital caliper that has an advertised resolution and accuracy of at least 0.01mm/0.0005.

2. Using a test bar from my micrometer I check out the accuracy of the caliper when measuring.
This pic shows my other IGaging brand of caliper......

3. After verifying the accuracy of the caliper, a lot of the verifying is developing a "consistent feeling" when closing the jaws over the pellet head. Here is how I judge the caliper pressure on the pellet head........
Keep in mind that pellet heads are often oval instead of round, often by .02mm or more (due to slightly mismatched die halves?). I also do several measurements of the pellet heads at the same point to verify the pressure used on the caliper jaws (measuring pellets by caliper is very tedious). The tediousness of measuring pellet heads did prompt me to create my own pellet head sizers which cuts the sorting time down to about 5 seconds for each pellet, during which the pellet head is swaged down and pellet skirt is "expanded/rounded" in a uniform fashion. I also mark the caliper jaws so the pellet head is always measured at the same point on the jaws........

Here are 9 tins of JSB Exacts straight from the tins labelled 4.52mm after they were measured and sorted......
Notice that most pellets from tins of Exacts labelled 4.52mm were 4.49-4.51mm.

As mentioned previously, while I'm not saying my pellet head measurements are exactly what I marked due to the caliper doing the "rounding off" at the "second metric decimal", I can verify that the various sorted sizes do fit the leade consistently within their "sorted groups" and are more accurate at the target.

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