Personally I use a new pin every time. They are cheap, and the risks are not worth saving, what? 13 cents or so.
One of the large size coffee cans with a resealable plastic lid is ideal -- the ones that hold 3 lbs or so. Put the cap back on, toss in, then if you want to be super safe, tape the lid down on the can.
Whether I should or not, I re-use slin pins 10-12 times before getting a new one. We're talking about a pin prick here and something that has only been in our own body, no one else's. Yes, there are bacteria on your skin. But, wouldn't you get an infection either way if your skin was dirty when you injected? Plus, everything I inject has either ba or bacteriostatic water which actually kills bacteria. I don't know how many thousands and thousands of shots I've taken over the years and never had an infection, abscess or anything like that.
Now, that's not what I'm going to advise to anyone else, but it's what I do and have never had a problem with it. I may be unlucky some day and get an infection. Or someone else may do this thinking it's fine and get an infection right away. But, I doubt it. Have you ever heard of even one person getting an infection from sub q shot of gh/peptide etc.?
Most abscesses are caused by contaminated gear- usually water based, but sometimes oil based underground stuff as well. The bacteria levels/contamination levels on this stuff sometimes comes back horribly high. If you are using bacteriostatic water and keeping everything clean as you reconstitute, you shouldn't have a problem imo. But, use your own best judgement.
For whatever it's worth, it takes bacteriostatic water about 2 hrs to kill all bacteria present in a substance- like GH. And, again, the contaminated stuff (pre-mixed aas usually) is often very very contaminated. If bacteria can grow in something that is 5-10% benzyl alcohol, something is way off- i.e. makers didn't use the right solvents etc.