Still not sure why are they causing trouble for you. It's a weak T1 that gets killed by a strong fart. For the claymores, since the squad room update exactly 100% of the time I could take at least 1 from the vendor. You can also access the other team's vendors. If for some miracle reason that is also empty, you can ask at req. If for some reason req don't want to give you (because they WILL have) ask OT. I would be really baffled if you could not get claymores. Even if someone hoarding them they will give you one if you ask. So let's just skip this part, you can get claymores easily.
Now as for runners evading it, maybe you didn't read my last reply. If you are a boneheaded marine and place it wide open in the middle of nowhere, of course they will evade it, all they have to do is jump over it. As in real life if you place a dark grey mine in the middle of a wide sandy field, of course everybody is going to see it. You are suppose to hide them like in real life. That's why I don't even consider it meta or bug that you can hide them (same way as xenos can acid traps) because you are supposed to. Use wood planks facing sides or lit flares north, empty flare box facing south to hide them. Also don't just plonk it down in the middle of nowhere. Even if they eat it, they will just walk back and heal. You are supposed to use your brain and you can most definitely can bait a runner to kill it.
Seriously it's a sh*tty T1 with no HP and low damage. All it has is speed, it's a scout if anything. Now lurkers on the other hand...oh boy those can break you arms with their first 2 hit if they get lucky with their ability and they are beefier. But runners, meh. Just a runner.