The problems with wadcutters have been mentioned in the previous posts. The detail design of the front of the pellet is critical to the extent of the problems, or more accurately, of the edges of the flat front. If the edges are square, i.e. the flat front goes right to the outer edge of the pellet face, then you have the maximum drag. Slightly rounding off the edges will reduce the drag significantly, the more the rounding, the less the drag will be. The drag is important as the lower the drag the higher the BC and the less the problems with wind and over stability at longer ranges.
The plot below shows how the drag varies with speed for different shaped edges. The numbers identifying each line refer to the ratio between the rounding diameter and the pellet calibre. Thus, 0 refers to a face with sharp edges, for a .25 pellet 0.1 has round edges of 0.0125 inches in radius, up to edges with a radius of .05 inches for the 0.4 line. The drag coefficients are derived from wind tunnel data for flat faces and some calibrated estimated data for pellets.
View attachment 436434 For those who do not like graphs, the values used are in the table below.
View attachment 436435 The 0.2 column values in the table were tested against the measured values for the Eley Match wadcutter pellet. The comparison is shown below.
View attachment 436438 The agreement from Mach 0.55 to 0.82 is relatively good, particularly as the 0.2 value is only a guess at a typical edge shape. The lines look to follow each other surprisingly well. The measured data below Mach 0.55 is more dubious, as it is the down range data.
With regard to the original post, the data is to show how sensitive small details of the shape of wadcutters are when it comes to drag, it will also affect the stability of the pellet.