Re: How common are "slamfires"?
Don't doubt your assessment of those BATFE agents you've dealt with. It may be a "regional thing" as well.....
However, in addition of subject reports there's pages upon pages of court testimony, video and audio, all describing how BATFE :
1. Refuses to establish any protocols or "standards" for its testing and evaluation of suspect arms.
2. Has declared in court such commonplace items as paper clips, shoe laces are "machine gun sears.....
3. Recently reversed decades of its own practices by ruling the process of a gunsmith's "accurizing" an action, installing a custom barrel, rebluing/finishing, or restocking to be "manufacturing" !
4. In a case pertinent to this thread, worked diligently for several months to come up with combination of soft primers and "cleaned/inspected" parts to get a suspect weapon with a known failure history to repeat the event causing them to get involved. The gunsmith is enjoying government hospitality, even though all parts were correct and unmodified.
There's a long history of this sort of thing in BATFE. Pardon me if I doubt their veracity or bureaucratic ethos.... >MW