Is gate loading an HMS carabiner bad?
Petzl seems to have a pretty clear warning and not to do this on their website. The skull and crossbones usually gets my attention.
But here on their website, they say it's apparently fine to connect multiple items to a HMS carabiner . . .
So . . . clipping two items is OK, but clipping three isn’t?
We all know that you get maximum strength from a carabiner by aligning the force along the spine and not necessarily the gate. Petzl says the “strength is reduced”.
By how much? Is it really a concern for recreational climbing?
HowNOT2 did a break test on this. With a limited sample size of 1, an HMS carabiner loaded up with several things clipped to it broke around 15 kN.
Is this significantly weaker than the rated strength of the carabiner? Yes.
Given that the largest possible force in recreational climbing is somewhere around 9 kN (and that's for a crazy factor 2 fall directly onto the anchor that 99.9% of climbers will never experience in their life) am I concerned about putting a load near the gate instead of upon the spine? No.
I want to share this as more of an “FYI, carabiners can be weaker than the rated strength if you load them like this”, rather than “OMG, if you do this, Yer Gonna Die.”
Modern climbing gear is incredibly strong and very rarely breaks under normal usage. There's lots of ways to get the whack when you climb. This isn’t one of them.