With the cylinder open (or closed) the "locking bolt" protrudes from the under-lug about 1/8". That is from the curved front of the recess in the under-lug.
If the locking bolt was longer - perhaps 1/16" - it would engage the recessed end of the cylinder pin providing for some frontal lock-up.
I did purchase the gun new, from a local dealer, about two years ago. It is a real shooter. (I punched out a 1 1/4" group a few days ago - 25 yds). I feel kinda silly that I haven't noticed this before now.
We've got a very reputable pistol-smith here in town. I think I'd better let him take a look and see what he suggests. I do appreciate the feed-back from you guys. jd