Have never swaged, but did experiment a while back with a LEM .22 Spitzer mould for a friend with an FAC Theoben. (I was used to casting for muzzle loading anyway, so it wasn't a major issue). I can't remember the exact proportion of linotype that was in the lead mix (it probably wasn't an ideal ratio for pellets anyway), but they cast fine and were then sized afterwards. Grouping was, from what I remember, about 1/2-3/4" at 60 yds or so - like with all pellets the barrel dynamics have a big bearing on performance. You see more of these style being commercially produced for FAC rated airguns as of late, so little point casting now other than for fun I guess.