I have been using them for a few years with no bother, my friend bought one a while ago which has a different knurled screw as per the link above. Mine have a straight knurled barrel.
He bought two more last week and used them today and we couldn't undo them. Thankfully they had been on a larksfooted sling on this occassion and so we could retrive the sling until we got home and got the pliers out. Even then they were really, really tight.
It seems that they don't stop like the old ones do, and you can easily (I mean no effort/one handed) tighten them to a point where you can't undo them again.
It is certainly not his or my technique and I've never had the issue before.
Has anyone else heard of problems/had problems? They are going back for a refund/exchange tomorrow. Maybe it is a bad batch? Could have been a big problem/knife out job if we'd been hanging on a belay half way up a route.
In reply to Martin1978: No, both used in normal use. No problems with the others, hence why I was wondering if it is a batch issue as these two were bought together.
Even now at home you can screw them up one handed (finger and thumb) and need pliers to undo them. That's not normal. Try as I might with my other carabiners none of them lock solid so I can't undoe them.
There is definiately something wrong with the carabiners. Just wanted to highlight the issue (try before you head out!) or see if it was a know problem/recall.
In reply to Martin1978: I've not had that problem with them, but I have noticed on mine (bought ~1yr ago) that you can screw them up to a 'stop' point, and then with very little force you can screw the gate further again. When you reverse it (undo it) you can feel the 'notch' as the barrel undoes. Never had them jam though, but to be fair I most commonly use them with my belay device so it's tightned and loosened with no load on the krab.
I've got a couple of Clog HMS krabs with the same style of barrel and I have had a bit of trouble getting them undone a couple of times. Even when they don't jam they're not very smooth and need a bit of effort to get it past a sticking point. This is in comparsion to my DMM Alphas which are really smooth in comparison. Never thought of taking them back though.