His AR15 was not modified for the purpose of the charges. It was a pre 1986 Oylmpic arms that used mil-spec lower but no auto shear or provisions for one. These were found to have a problem if you rig the test with out of spec ammo(or you happen to run into some) and a recall was ordered. His was just never recalled because the transfer took place before the recall. Even with the fault it was difficult to cause the malfunction hardly making this a machine gun.what hasnt been widely known is the fact Olofson had altered the weapon in question in a way that the BATF can construe was an attmept to make an illegal machine gun. In this particular the defendant screwed himself by messing with his weapon. they can sayabout anything they want to, to prove intent and in olofsons case, intent was key item that got him convicted.