I don't like tubes in old doubles, but that doesn't apply to your Miroku. If you like tubes, it makes the gun more flexible, as you said. The chokes on my Miroku sxs were opened from M&F to IC and Mod and work just fine with steel (which shoots tighter anyway). With lead, the gun is just right for doves. My vote on your gun,if I had one, would be to just open the fixed chokes...Geo