Just built my first AR upper (on my old lower) but encountered one hitch: I torqued down the flast hider (with the crush washer's concave side up) but the vent holes are aligned toward the right, so two holes are on the left (looking down the barrel) and three on the right, with the little fin between the holes being vertical. How to I get it to sit "normal" with one vent hole vertical? Should I take it off and use a washer for a shim or something? If so, what size? I apologize for the crappy pic.

New crush washer?

If so, you tightened it too far. If not, then you need a new crush washer.

It can be shimmed with peel washers to time it also, but a crush washer is all you need.

You tightened too far, so you'll need a new crush washer.

Over tightened, needs a new washer, then reinstall and stop tightening when it is timed correctly, it only takes about 20 lbs torqued to get it timed correctly.

You might need to tighten it more actually.  If it's a new crush washer and your first time doing this, a lot of people think they tighten til they feel it start to torque and stop, when you really are just starting the "crush" and just need to keep going until it lines up.  A new crush washer should be caple of about 1.5 rotations at least once it starts to crush, and the force needed to do it will ramp up at first (feels like it's torquing), then will sort of remain constant over the rest of the rotation.

I guess a good way to ask, if this is a new crush washer, did you spin on the flashider until hand tight, and then just torque it slightly past that?  If so, you just started the crush and need to keep going until it lines up.

Is this a serious thread? Lol. OP, it should be obvious that you've either tightened it too much or not enough. The point of the crush washer is to keep tension on the flash hider so it doesn't come loose during use, but it allow has a very large allowance built in so the flash hider can be timed properly. If you went too far and tightened it past 12:00, you'll need a new crush washer. If you haven't tightened it enough, you can torque it, loosen it, and torque it repeatedly until it comes back around to top dead center.

ETA: Looking at your pic again, you're really not that far past 12:00. Depending on how much torque you applied to it to get it where it's at now, you MIGHT be able to get away with just backing it off a hair to straighten it out, while still retaining enough hold from the crush washer to keep the muzzle device in place.

A proper CW should give you ~270 degrees of rotation.