I'm swapping a couple of my uppers around, and putting a Phantom flash hider on one in place of the Cav-Comp that's currently there(I got another preban lower). I've always used either the A2 Birdcage or a Vortex on previous builds, and wondering which way to do the phantom. On the Birdcage I always index it with the center of the 5 slots pointing straight up, using a peel washer, a split washer, or a crush washer. The Vortex I've always used without a washer, and let it line up however it wants. With the twist in the tongs and the complete flash suppression I figure there's no wrong way for it to be indexed.

The Phantom has 4 slots, 4 notches, and the usual 2 wrench flats. I like the way it looks with the flats on the left and right sides, but I don't like how it looks with a washer(too long). It's a 14.5" barrel so I need to permanently attach the Phantom, but I don't need a washer to make length.

Whatever I do it's going to have to stay that way.

Thoughts?

With a washer or without?

Maybe that's why I'm second thinking this at all- This one has the slots at 12, 3, 6 and 9 if the wrench flats are vertical. If I put the slots at roughly 2, 4, 8 and 10 the wrench flats will be diagonal which I'm sure will bug me more.

It's made by Yankee Hill, the guys that make Bushmaster's, so it seems like it would be normal...[?]

Since it's suppressing the flash I don't think it'll matter to have one at 12 o'clock, but like Winston_Wolf said I'd rather not have one at 6:00. I guess I could hold the rifle at an angle if I go prone.[;)]

Use no-tack's method exactly.  When you're prone, it won't make ANY difference how it's indexed; you'll still kick up dust.  Try it if you don't believe me!

But you don't want the gasses being vented into your sight line if you can help it.

Index so the front notches are at 12-3-6-9 and the slots are offset.  Trust me.

-Troy

That's what I did. The wrench flats are not vertical, but the notches are at 12-3-6-9 and the slots are offset. I pinned it and welded over the pin. Good enough for now, I may end up registering this receiver as an SBR eventually and it won't matter anymore.
It sucks that the A2 birdcage I originally wanted to use wouldn't make 16", and a Bi-Lock is $85. I think I'll like the Phantom though.