Dr. Martin Fackler-US Army Wound Ballistics Expert
This is my all time favorite website on this subject. There is a wealth of information here. Dr. Martin Fackler has a lot of research here that will dispel alot of myths. Before he retired he was head of the US Army wound Ballistics Laboratory. Take a look at some of the reports they are worth the time.
http://www.firearmstactical.com/wbr.htm
The primary issue with the Forward Assist is that
the most likely thing to initiate its use is a fouled or obstructed chamber and / or a dirty cartidge -- that is the worst possible time to use it. It was and is an unnecessary addition to the design. Better and safer to have left it off and forced the shooter to look in the breech and clear the problem.