Sometimes you can make a little profit off that trick. Some people do not bid as high on coins that are not straight in a holder, so you can get a good deal. Then you straighten them and resell (or keep at a discount!)
I hold the case with only my fingertips on the edges. Then I move my hand from the wrist in a circular motion, as if you were using a whisk. If there is any looseness at all, you can walk the coin right around to where it belongs. No banging required.
Based on similar experiences, I believe one will determine the coin can be rotated 360 degrees, either counter or clockwise, in a holder without the elastomeric constraining ring, JMHO
Normally accepted definition for a gasket: a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. The constraining ring is generally not under "compression", possibly having a "tang" on outer diameter to restrict rotation, while the inside diameter provides friction on the irregular outside diameter of a coin JMHO
Come on, Rich... lighten up. Regardless of if the term fits your narrow definition, they're generally referred to, right or wrong, as "gaskets". Sometimes it's best not to be as correct/proper as is possible, especially on a forum where some may not quite understand what you're saying. Just friendly and respectful food for thought...
Thanks for the corrective input, as I also tried to implement. As a design engineering specialist, I've looked at the slab design to easily implement an "air-tight" design. I've simply constructed same for some of my greater valued oxidization/corrosion sensitive coins. The coins are protected by a commercially available "gasket" which effects the function of the component to which you applied the same name, while also implementing fluid movement restriction. Also just some "food for thought" for those so inclined, intended in the vain attempt to educate. JMHO
Actually, it's about 135 degrees from upright BTW, not 90. Oh well, maybe geometry was never your strong point !