Jeryray, if you already had a smith shim the cylinder, you should be fine. It sounds like you are close to max spec.
Measuring tenths (.0001) or even thousandths (.001) is part art and part science. Skill will affect the recorded measurement. Gauges can compress, parts can spread, and temperature can also play in.
With feeler gauges, you want a very slight drag. Just touching. No clearance and no interference. This will give you the best number. Closing the cylinder can mask an interference, which you correctly determined makes it tighter than .012.
You can find a nice set for less than 20 dollars that will go down to .002 or .0025 and up to .030. Very useful if you tinker.
If you have say .009 or .010, and aren't spitting lead, I say shoot it, and keep an eye out. If that gap increases, or you see lead, investigate further.
Merry Christmas
Rich