I recently got a tip from a long time well known breeder about how to tell if a male likely locked without actually visually seeing a lock. It makes perfect sense to me and I have observed this fact on 3 known visual locks....
After I pull a male from a females tub I immediately pop him. On all 3 instances of visual locks I have checked so far this breeder has been correct about these observations. One of the males penes is slightly larger, has more of a dark red/purple coloration, and is wet. Twice with no visual locks I have seen that the male's penes are normal looking.... same size/color.
I would take pics, but I don't have a third hand while I'm popping. I was just wondering if anyone else could check these observations on known visual locks and post their observations. Next pairing I will set up my camera on a tripod and attempt to take a short video.