About 1972 is the date I use for the change from front to back strikers. There was apparently considerable flexibility in the new regulation. Also, any matches in stock at that time could continue to be sold and used.

Whether you collect matchcovers or full books is a matter of preferance. As a collector of casino 'stuff', I like to get it as close to original conditon as possible... which means I prefer the full books. However, if not all the matches are present, I strip the remainder and collect it as a cover. Older matches (1940's and earlier) are quite difficult to find as full books and will always be worth more when complete. I collect covers if I can't get full books, so there will always be a demand for covers-only. If the match is a Lion "feature" book, I believe the matches should be left in even if a few are missing as they complete the 'picture' of the collectible.

For full book front strikers from Nevada, I believe the value is 2-3 times that of a matchcover only.

Since there are no books and catalogs on casino match collecting (yet), it's a matter of opinion of valuation. Roughly, I would compare a stripped matchbook to a cancelled (drilled or notched) casino chip.