Does Size Matter?

Does size really matter when you are after the best accuracy in air rifle target shooting?

Washing and weighing pellets is an option followed by resizing the pellets to a diameter selected by the shooter after a lot of trial and error on the shooting range. This resizing should give pellets with a consistent head and skirt diameter that may minimise any mechanical errors in the shooting process.

Shown below are a set of pellets that were originally washed and weighed and each of them weighs 8.4 grains (+/-0.05). The 6 best formed pellets were then selected and pushed through a purpose made sizing die manufactured from 20mm thick tool steel which had been lightly oiled.

In the die are 6 holes ranging from 4.48mm to 4.53mm diameter in 0.01mm increments, the holes were formed using a precision EDM process. Part of the die is shown below.

The images below start with a pellet resized to 4.48mm shown at x2 lifesize and then just a close up of the skirt at x5 lifesize. The image sequence continues with each pair of images showing a pellet sized 0.01mm larger until the last pair of images show the pellet sized to 4.53mm.

I would of expected the parallel land formed by the sizing die to increase in size as the pellet were sized to the smaller diameter i.e more deformation of the pellet. This small test sample does seem to show that increase in size trend, the variations could easily be down to minor changes in diameter of the original pellet skirts

The following test used 6 fresh pellets all measured before sizing and had a nominal head diameter of 4.48mm. Each pellet was then resized and remeasured

This pellet was resized to 4.48mm and measured 4.47mm after sizing

This pellet was resized to 4.49mm and measured 4.47mm after sizing

This pellet was resized to 4.50mm and measured 4.48mm after sizing

This pellet was resized to 4.51mm and measured 4.48mm after sizing

This pellet was resized to 4.52mm and measured 4.48mm after sizing

This pellet was resized to 4.53mm and measured 4.48mm after sizing

Most of the pellets show a minor reduction in the head diameter with the maximum lead removal clearly visible on the pellets sized to 4.48 and 4.49mm

All measurements were taken using a digital micrometer accurate to 0.002mm but realistically 0.01mm is about as accurate as it is possible to measure.

So, back to the question:

Does size really matter when you are after the best accuracy in target shooting?

Personally I have no idea, but if you think it does help then it probably does

Happy sizing

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