The other important type of evidence preserved on the lead projectiles is that from their impact immediately after firing. All but three of those from Bosworth show what appears to be impact damage resulting from firing, rather than from later agricultural activity or during recovery by the detectorist. The scale of the damage ranges from the highly destructive, where lead has been ripped off the surface of the iron dice (Figure 7.20), to very slight gouges (Figure 7.24). With most impact evidence it is not yet possible to say if it resulted from hitting a human or horse target, arms or equipment, a tree or hedge, or simply the ground. Experimental firing suggests the latter is the most common but, as the experiment were designed principally to explore firing evidence and range, they have so far enabled only one type of impact evidence to be clearly characterised. It has however suggested that variations in land use at the time of firing are likely to have resulted in major differences in the character and degree of impact damage.
The first important conclusion is that round shot fired at or near point blank, if it missed its target, is likely to have bounced several times before coming to rest. The experiments show balls bouncing up to seven times and with a final range, for the 60 mm rounds, of up to 1.2 km.154 These bounces, depending on the ground conditions at the time, will often have left a distinctive impact signature in the form of rotational impact grooves, which extend around a substantial part of the circumference (Figure 7.47). High speed video has revealed that the ball typically spins as it travels down range and so these marks, which are frequently seen on small arms bullets as well as artillery rounds, are probably created when the rotating ball contacts a small pebble as it bounces down range. Where there are several superimposed rotational impacts running in different directions, this seems to be clear evidence as to the minimum number of times a ball has bounced. However, in certain ground conditions, particularly on damp turf, 60 mm rounds were seen to bounce several times creating deep gouges in the ground but without any visible evidence being imparted to the ball (Figure 7.48). In contrast, deep gouging was seen when firing took place on very dry, hard ground in a stubble field. On ploughed ground the impacts could be even more substantial, although the number of marks and the degree of damage varies according to how stony is the topsoil. Thus a variety of factors seem to determine whether a round shot carries impact damage, its form, and the degree of that damage. This impact evidence varies greatly in shape and surface characteristics, as well as degree of deformation but at present we lack sufficient experimental data to interpret most of these signatures (Figure 7.49).