Kanga covered it very well.

I'll throw a few pennies at it as well though.

Long and short of it is that even though he might be shooting faster with an underspined arrow, there are light weight arrows that are the correct spine that will not only shoot much faster, andbe safer, but will also be much more accurate, espeically with broadheads.

Some of y'all have probably read my story about buying arrows when I was in college. Difference was back then I was ignorant to what I needed, or what spine was... or what those numbers on the arrow meant... ignorance is one thing, and its forgiveable and excusable, especially when the offending party admits it and asks to be guided.

But as Ron White said, You can't fix stupid.... doing such a thing on purpose would be like gargling with nitro glycerine in my opinion. Granted the odds of it happening with good, intact arrows are slim... because like most things in this modern world of class action lawsuits, arrows are typically over built.. just like tree stands....and having 75gr heads improves his odds... but if he ain't flexing those babies before every shot then he is just shooting on borrowed time.

Personally Black stick... I don't like standing directly next to anyone while they are shooting... there is always a what if in my mind. I had a customer shooting a crossbow about a year ago and it blew up while I was standing there... something hit me on the cheek... just below the eye... don't know what it was... didn't even leave a mark... but it scared me.... I keep my happy self three steps closer to the door because of it...