I got about 2103 with butches 110gr of IMR 4831 and the recoil was considerably more than RL-15. 94gr of RL-15 with woodleigh softs gave me an average of 2074 and with solids I got an average of 2102. The 96gr in soft gave me 2102 aswell. The weather was pretty cool so that could of affected the chrony but anyway these are the averages it gave me. I have always liked RL-15 for my .470's. Ross siegfried in one of the double gun journals seems to think that this is the only powder worth considering in doubles. He uses dacron as a filler and I have never tried it. G. Wright in his book "Shooting the British double rifle" mentioned that he used regular grey packing foam and never had a problem with it. That is what I have been using and have also never had a problem with it. He has a picture of the foam in that book to give you an idea of the kind he is talking about if you decide to use it. In the .500, I use roughly half an inch of the foam cut so that it fits snugly in the cartridge. In the .470, I use one inch pieces cut snugly to fit the .470 cartridge. Hope that helps.