Your Sumo and BFK bracelets use pins with collars to join the links. You are either missing the collars on the pins which will cause the pins to slip out or the collars may be a loose fit on the pins causing them to slide off. If the collars are still there then they may need replacing or you may be able to gently squeeze them to obtain a tighter fit on the pins.
Here's a picture to give you an idea of how they look and may assist you in diagnosing the problem.
Thank you guys, I found two collars in the watch box for the Sumo and am replacing them now (just got it yesterday from a WUS'r). I'll go over both bracelets to improve the fit of the pins. I'm new to both of these watches and usually wear straps so this is very helpful info for me.
Usually it's an issue with having the collars on but not on enough so in effect they aren't doing anything especially with external collars. The internal ones have to be on or the pin won't go through and if the collar is damaged it usually won't go back in the hole in the link.
Yes, it was good learning experience and was able to get them all back to spec, none of them are remotely loose now...of course now it is a moot point, the rubber MM strap showed up today so the Sumo is on that one. I've remedied the BFK bracelet too and it's much better as well.
Can't thank you guys enough for the info and help. Exactly what was needed!