TSchirm and Josh Perdue,
Along with the advice from Pavan and James on holding the bow, you may want to play with the brace height. I use a 6.5" brace height on most of my Hill-style ASLs because at brace my 5" feathers clear the shelf by just a little bit. Depending on the bow, I can get a little more bump in the hand if my brace height gets lower (as the string stretches/settles in). Play around with your brace height a little and see if you can find a sweet-spot.
Different strings and string materials can also have an effect. For most of my ASLs I shoot flemish-twist 12-strand or 14-strand 8125 or D97 strings with padded loops (4 add'l strands of B50 or B55 in the loops). I notice a significant difference in handshock (less, that is) compared with B50/B55 Dacron strings. Some guys like B50/B55 on their ASLs; they say it has a "softer shot feel". Others like the slight performance gain and the shot feel of modern string materials. Different strokes for different folks.
The only ASL I still use a B55 Dacron string on is a Hill Big 5 by Craig Ekin that's probably at least 10 years old (maybe 15 or 20 yrs old). It's made to handle modern low-stretch strings, but it shoots my long 2117 aluminum arrows more accurately with the B55 string (with the B55 string, this bow is apparently better tuned to match these arrows). And this bow is nice and quiet in the hand with the Dacron string (very mild bump in the hand at the shot with B55 string. With an 8125 string, it's the quietest-in-the-hand ASL I've ever shot-- no discernable hand shock at all).
Every bow is unique/different--even from the same maker. I've got a couple other Craig-made Howard Hills, a Northern Mist Classic, a JET Leopard, a Dave Johnson red cedar ASL, and a 7 Lakes string-follow ASL. I love shooting them all, but it's uncanny how quiet in the hand my old Big 5 is.