I think it is hard to say that Mike. It would depend on when the damage to the SBJ/1 silencer occurred.
Was it before that night, or it may have been attached to a rifle and damaged that night after some shots had been fired.
... To my way of thinking, there were two states that the silencer (SBJ/1) could have been in, (1) undamaged, before it recieved a hard knock, (2) in a damaged state, after it was knocked. It should have been possible to tell if a bullet had been fired through this silencer, whichever state the silencer was in - since, ther are no rifling marks in the silencer, unlike the barrel of the anshulz rifle, and therefore, any bullet entering and passing through the silencer, and exiting it, will be distinctively marked with straiations, that are unique to the silencer, marks that will not be found on bullets fired through the gun, minus the silencer. These straiation marks may not be visible once the silencer becomes damaged and bullets fired through it shatter and disintigrate...
Mike
We have discussed this before in part in earlier posts. An undamaged silencer should leave no marks upon the fired bullet as the hole through the baffle plates has a greater diameter than the bullet itself and there should be no contact between the bullet and the baffle plates. You mentioned earlier that it might be possible to tell from a microsopic examination of the spent cartridge cases whether they had been fired through a silencer, based upon the greater backpressure expanding the cartridge case more when fired with a silencer fitted than fired without the silencer. I would be interested to hear more about this at some stage, bearing in mind the apparent existence of some of the cartridge cases which were not destroyed by Essex Police.
As far as damage to a silencer is concerned, if the baffle plates became out of line in the silencer tube, ie were at a slight angle within it rather than lined up evenly within the tube, it is possible that contact could be made with one or more of the baffle plates causing damage to or even fragmentation of the bullet. However it would take more than a slight knock to do this. The end cap would have to have become loosened to allow some movement of ther baffles inside. Alternatively there would have to have been a very major knock sufficient to bend the tube itself, or to dent it.
On a separate point referred to earlier, it is correct as you have stated that silencers are regularly fitted to air rifles, and the Parker Hale silencer is commonly used for this purpose. An air rifle would not be the first choice for a suicide, but would be lethal at close range. You have mentioned that the air rifle at WHF may have been the more powerful version, classified as a section 1 firearm. In that case it would have been just as effective as a .22 LR rifle. There seems to be very little information about this air rifle. Do you know if it had a magazine, i.e. could fire multiple shots, and whether it was spring or gas operated?