On my drywasher I use this type of riffle but it is in reverse compered to a sluice box , It gives a nice place for the gold to settle under the lip , Harder for the air to move material over & out of the box , I have them all the way down the tray.
Beach High Banker, Sweep Jig, Whippet Dry Washer, Lobo ST, 1/2 width 2 tray Gold Cube, numerous pans, rocker box, and home made fluid bed and stream sluices.
Just my thoughts.
I envision two potential disadvantages to having an overhanging lip facing backwards on a drywasher riffle. First is that the clean out volume would be excessively large due to the static stack of material trapped by the lip in addition to the normal banked material stacked against it. That static stack would in effect compress and not allow any more gold to penetrate it by displacing waste material and would actually be the cause of the second disadvantage that I envision...potential loss of gold by just ramping over the riffles.
Good luck.
PS Hungarian riffles are all about hydraulics and not applicable in drywashers.
thanks guys,i think i will just glue in two of ten and try it,that way i can take them out in the field if i dont like them.like i keep saying i think i really just need better ground.
brad