[Phlogiston]

Keep in mind that none of this - or very little applies to the copper Mershons. This is really about the Sprague caps that are nickel plated.

Most, but not all of the copper Mershons have either a pressed on cap or a screw base (no screw basses in Philcos). These are dealt with differently.

I would also add that my method for grounding is to attach to the can its self. Sometimes this is almost necessary when stuffing a 10 or 15uf film cap into the tube. In the majority of cases there is either a hole, that you made under the cap (pressed on top cap) or a vent hole that makes for a nice spot to solder a ground.

Here is another little tip if grounding the can. There is only limited torque that can be applied to a glued in base. This may make chassis contact questionable. In those cases that use the base/ground ring/contact, I make a small solder joint to the can and that ground ring. These were used in some Philcos. I also used this in the Spragues that I installed into the Strat. An intermittent ground will cause all kinds of noise to say the least.