Hey Nitro.

If those slugs regulate that well at 100 than great. Remember, most of the full bore slugs loose their stuff after that, so although they may group well at that range, by 125 the groups may be 2x+ if not way more.
I was shooting Brennekee 2 3/4 20ga that shot into 1/2" at 50 yds (single barrel) and about the same at 75. Groups were 8"+ at 100. Switched to the faster 3" and went into 2.5" at 100. The Lightfield is just a pinch ahead of the Brennekee in speed and BC. Those grouped into about 1.5" from the same barrel. Speed matters.
Another thing, we are shooting composite bullets here so at some point the accuracy will probably max out. It would be cool to make them shoot better and I would probably move over to a round ball and do the handload thing. They hold their power for as far as they can hit.
One more thing, I don't know what you used for a reamer but I used an extended forcing cone reamer on my chamber as that was what I had at the time. Don't know if it was that or the barrel that made it as accurate as it is.

Hope that this may be of some help.

Good shooting

Tom