Knight 500s come with the FPJ plug as the standard. Not the best choice for BH209 especially if you want to shoot a conical. The true Lehigh plug though should work fine. It does in my SuperDisc with the Bullshops and a veggie wad. You want conicals sized around .001-.002 over land size. Slip fit like a White would be pushing your luck if the shot of a life time was available.

BTW...DONT go over 80gr by volume of BH209 with these big conicals. FPS will get too high and you could run into pressures that are getting kinda high.