Nelson Conversion question

About a year age I purchased a new Nelson Conversion and just started shooting it this fall league season. The unit is on a dedicated frame and topped with a Matchdot. I have about 750 rounds of CCI Standard velocity fired through the unit. Last night I shot a 276 league score and during a practice match shot a 92 slow, but my timed target had one just touching the outside of the 6 ring at 10 o'clock. My rapid had 2 (side by side) outside the scoring rings also at 10 o'clock. The rounds at 10 o'clock is something new for me.  

I did check the rod and it was tight (no movement when I checked it), and the Matchdot mounts are also tight. Besides user error, which is very possible, is there something else I should check mechanically? 

Thank you - Tim

When in doubt, bench the gun for 10-20 rounds and see if it duplicates.
Odds are it’s you.