Not to derail the thread, but BOM I like your signature. My biggest complaint with gun forums is the reception most newcomers receive when they ask a simple question.
On topic - the Wall Drill
(Wall Drill), using a spent casing, or coin
(Balancing Act) and the Original Poster's drill all seem like good dry fire practice. I know I do the Wall Drill several times a day.
When I have a little more space (about 10 yards) I insert one of those laser bore sighters with adjustable end pieces that fits in any barrel up to .50 caliber. It offers some visual feed back, kind of a poor man's
SIRT, also you'll make damn sure to check the gun when you're purposefully obstructing the barrel.
Does anyone else have a way of dry fire practice they particularly find helpful or enjoyable?