Gnomon, I'm not understanding something. With Skeets, you have two different heads. One is for 12/16, the other for 20/28. Which one doesn't work for you in Merkels? I have a Sauer 20 that's overbored by about .012 from standard, and the 20ga Skeets head works just fine in that gun. Only problem I've had with Skeets are on guns that are both underbored and have a whole lot of choke. On a few like that, they won't go in the muzzle. You can still get a reading on the bore, by going in from the chamber. But you can't read choke.
The 3 balls do not extend out far enough to contact the bore in the Merkel 20 ga. They are about 4 thou shy. The gauge works fine on all my other 20 ga guns. I bought my Skeets used and thought I'd save some money but in the end it wasn't worth it.
