Disappointing Results From A Box Of Bank-Rolled Half Dollars With Two Silver Enders

I recently acquired two Loomis boxes of half dollars at a local bank that commonly gives me good CRH results. The first box was a stinker -- but I found two rolls with 40% silver "enders" in the second one. Therefore, I anticipated finding a total of ca. 20 silver coins in that box (a statistically-reasonable outcome after examining 100 coins in a box that contained 1,000 half dollars).

But I found only four more 40% silver half dollars in it (including an odd chrome-plated 1967 half dollar). I typically find fewer silver coins than I expect in a box with silver "enders". Perhaps the slightly-heavier silver half dollars preferentially wind up at the end of a roll of coins before it is wrapped. But I don't know enough about the mechanical process that Loomis uses when it counts and wraps loose coins to suggest that this is a reasonable explanation.

Have other CRHs had similar experiences with bank-rolled half dollar boxes that contain silver enders?