barely legal,
Don't have the 50 but have the Knight 45.I use Clean Shot powder,NO PELLETS.I've had great luck w/clean shot in this gun!

With a 240-300gr sabot I get good groups w/130gr of loose Clean Shot.I've also used 195-240gr sabot with a max load of 120gr loose powder.I'm slowly workin this gun up to 150-175yrd kill shots.

IMHO you might want to START w/110gr of your choice of loose powder and a 240-300gr bullet.Find your used plastic sabots and inspect for severe blow by,splittin or severe deformation - NOT GOOD.

If your shootin Power Belts and having problem with groups- throw them in trash and buy somethin else.They either group great or fly everywhere.Heard it here,seen it and been there with them bullets!

The big thing I noticed with my Knight,is sabot goes down barrel very hard/tight.Knight tech told me 3yrs ago,thats a good thing.As far as groups go,I finally figured I was deforming bullet in attempt to get down barrel.A starter with a PLASTIC coned tip will almost eliminate bullet distortion on the start anyway.I started using plastic tip starter about 8 yrs ago.It improved groupS greatly on my T/C inline and CVA side lock.

I also bought a kit with various brass screw in tips.You screw proper tip on starter and the rod,depending on HP,Polymer or Spitzer tip bullet.If you buy the "Precision" spitzer or polymer tip sabots they come with a plastic tip you screw into rod.

All this might seem a bit Anal,but its the little things that can change a group from size of paper plate at 50-100yrds down to a silver dollar!

All this nit picky stuff greatly improved my groups in 3 differant smoke poles.

I'm sure one way or another you'll get your Knight tweaked the way you want it.Good Luck - AL