There are chopper guns that mix the resin / catalyst and chop strands of
glass (hense the name Chopper Gun) in very cheap boats but are used
primarily in other industrial layups, like shower stalls, etc.

Then there are guns that mix just the risin and catalyst at the nozzle..
These are used in some boat production to apply the resin/cat. mix to the
mat and roving before and during layup (or wetting out process).

If your considering use for a barrier coat on a single hull you would be
better off using a premix in a paint gun with special nozzle. If it were for
a boat yard, the nozzle mix type gun could be used but would have to be
calibrated to the epoxy mix..

BTW. I don't know of any barrier coat that would require a chopped strand
application, so Chopper Gun would not be appropriate.

But then, What do I know..

Steve
s/v Good Intentions