RE: question about risers...
I would have to agree. If a bow thumps that hard I wouldn't buy it! Some of the more production longbows come to mind.
This big 5 I recently bought thumped pretty hard. A simple change to a dynaflight string took care of all but 98% of it. what's left is just enough to know you are shooting a longbow but no more.
Heavier arrows will also absorb some of the thump, between the two it can get rid of the majority of it even on a bad bow. Then there are those bows that just belong in the scrap heape, I'll leave those names out....you'll know them when you findem!