I had a full set of sizers from UK Niel for me to use and others to try differnt sizers.
From some experimentation last weekend at the club my results were as follows using JSB 4.52's as a start
50yd Grouping average over 3 groups of 5 shots. Windage being ignored for this, up/down variation.
56mm group = Unsized straight from the tin
42mm group = Sized 4.52 straight from the tin
33mm group = Sized 4.51 straight from the tin
29mm group = Sized 4.50 straight from the tin
26mm group = Sized 4.49 straight from the tin
26mm group = Sized 4.48 straight from the tin
29mm group = Sized 4.52 Weighed 8.4-8.49 band
25mm group = Sized 4.51 Weighed 8.4-8.49 band
20mm group = Sized 4.50 Weighed 8.4-8.49 band
18mm group = Sized 4.49 Weighed 8.4-8.49 band
15mm group = Sized 4.48 Weighed 8.4-8.49 band
Slight wind coming either way. Windage variation moved pellets upto about 30mm each side of centre. Windicator at target moving constantly from one side to other.
From a bench with bean bags, shot at 25x mag
Measured from front of bench.
These are only preliminary results but it does seem that the 4.48 sizer has the edge.
For true data need an indoor 50yd range. The 55yd versions of the weighed pellets increased on average about 4mm
Using pellets from the 8.35-8.55 band range groups increased invertical variation by 3mm
Pellets weighed over a number of evenings (5 tins used) and seperated into 4 groups being
<8.35grains (lowest measured came in at 7.41grains but in excess of 50 per tine <8.2grains)
>=8.35 to <= 8.55grains ( not including the 8.4-8.49 pellets)
>8.55 grains (highest seen 8.82grains, only 30ish per tin >8.6grains)
Truth will be this weekend at GP1 lovingly prepared pellets ready for use swaddled in foam. Probably make no difference to my scores