Originally Posted by verminator
If I recall, in that specific case, there were many guns involved. The defendant in question was not convicted for the rifle taken apart by the labs, but for a rifle that was work in progress (conversion from .177 to .22). Also for .22 LR ammo found after letting their fire-arms license lapse.
That said, the testing may well have some influence on the Judge/Jury.
The rifle in question was owned by "Lionel" of the BBS. He was a "Hostile witness" in the case. He said the rifle was shooting at well less than the 12FPE, which was proved by the initial testing. Later testing with the removal of parts let the rifle shoot from around 3 to 30 FPE. Correct on the ammunition though.
You may be getting mixed up with a case from Ripley (Yorkshire) where rifles that were in pieces were reassembled and tested over power. Again a conviction was obtained.
In both cases an appeal was not considered due to the sentences passed. On appeal the sentences could have been increased.