Cutting open spear track

[TG SPEARGUNS]

I was wondering how others where cutting the tracks for the spear on an open track gun. I have been using a 1/4" round nose bit and then sanding the track to the appropriate size with a rod and sand paper. I know some 9/32 and 5/16 ball end bits are available but at $50 i was hesitant to buy one.

[hglucky13]

i think the first one i made i used a 5/16 core box bit i bought at the local lumber yard for about $12. worked good. i went ahead and bought a ball end bit to make enclosed track also, and i use it now. but for an open track i don't think you need to spend the extra dough.
later
alan