ok ill take them one question at a time.
these are actually my grandfathers crossbows (73 yrs old. only way he can still hunt during archery season)
-one is a maxpoint 340 advertised fps the other is a barnett revolution 335 advertised fps.
-arrow length on the maxpoint is 20 (carbon, 100grain muzzy)
-arrow length on the barnett is 22 (alum, 125g)
-fps for both is right at 325 give or take 2-3
-grains per inch on the carbon is 13.1 i cant get on the barnett site right now so im not sure on the gpi for the alum
-the carbon total is 405g. same answer as above on the alum. ill keep checking -and post the info as soon as i have access to it.
-the broadheads were chosen based on the recommended size each manufacturer suggested.
-both are extremely accurate. he can put a 4 inch group at 40 yards but would only feel confortable under 30 yds.
-asking because it seems like the barnett has a much greater impact force because of how much further it penetrates the target. maybe it will make a difference when harvesting a deer and maybe not. thats the reason for the question.
-the barnett seems to also shoot a flatter trajectory. 20-35 yards you just put the red dot in the middle of the target and pull the trigger on the barnett. on the maxpoint it is 1-2 inches low at 30. not much of a difference but definitely not as flat.

i shoot a matthews lx myself and i just dont have a lot of knowledge about crossbows.

any help is appreciated