When I was switching out the FSB on my SBR, I decided to switch the FS at the same time, and put on a phantom that has the closed slot, but indexed the closed slot to the top, instead of the bottom.

Does that make any sense at all, or is it completely retarded?  
 

Here's my thinking:  The purpose of a closed slot in the FS is to avoid any "dust signature" right?  Or is it also to reduce muzzle flip?  My understanding is that it was primarily to avoid kicking up dust under the muzzle when firing prone.

Well, since I've got a vertical grip on the rifle, and it's more of a fun rifle - with possible home defense application, but not much anticipated "field" use -  I don't image I'll be doing a lot of prone shooting, and kicking up dust from the barrel being close to (dusty) ground.

But in some lower light conditions, and when shooting ammo like XM193, I have noticed that there is occasionally a flash that is visible that can be seen through the sight (EOTech).  It is MUCH reduced with a regular phantom, as opposed to a regular A2 - but wouldn't putting the closed slot on the top also reduce any visible flash to the shooter even more?  (or would any benefit be lost by increases in muzzle rise, because now expanding gas is being directed downward and not up).


Does/has anyone else deliberealy index the closed slot on an A2 or Phantom on the top?

just take it out, shoot the whiz out of it, and see if you like it...
can always put it back to normal.
now, maybe if you stack 2 together; 1 up 1 down...

Quoted: just take it out, shoot the whiz out of it, and see if you like it... can always put it back to normal.

I tried it today - to make sure the FSB worked, and I hadn't screwed up anything with the gas port and stuff like that.  

It seemed fine - and I'd IMAGINE that it would be better for the shooter in low light - given the short barrel.  I don't think there was more muzzle flip - partly because I've got so much crap on the SBR (plus the heavy barrel) that it probably weighs more than a stock A1

now, maybe if you stack 2 together; 1 up 1 down...

Brilliant !!!  

As you said ... it's just a "for fun" rifle ... so whatever floats your boat I suppose.


But I am sure you will get a lot of WTF looks at the range!  

Quoted: Or is it also to reduce muzzle flip?

Exactly.

The gases vent out the sides and top, forcing the muzzle down. By putting the closed portion of the flash suppressor on top, the gases will vent out the bottom, causing the muzzle to rise.

Quoted: Quoted: Or is it also to reduce muzzle flip? Exactly. The gases vent out the sides and top, forcing the muzzle down. By putting the closed portion of the flash suppressor on top, the gases will vent out the bottom, causing the muzzle to rise.

I would not worry about the muzzle flip at all, you should have a whole bunch of time to get a sight picture waiting for the dust to clear.

Joe

Edit:
Ok I forgot that you do not shoot in the prone position and this is only a fun gun, so yes why not do it the wrong way.

If you like it I dont see a problem with it. The purpose of it is to reduice muzzle flip but if it helps with the muzzle flash on upside down then you have accomplised your goal seems like.

i install mine with the fsp being inbetween the two top slots, canting the fh a bit

Not something I would want to shoot "Creedmore" style!

Scanned from one of those Navy SEAL books:



Close up:



I'd say the idea definitely has merit.

That probably just comes from swaping back and forth from a can to a flash supressor and losing the washer in the process.

Quoted: Quoted: Or is it also to reduce muzzle flip? Exactly. The gases vent out the sides and top, forcing the muzzle down. By putting the closed portion of the flash suppressor on top, the gases will vent out the bottom, causing the muzzle to rise.

So was the original reason for changing from the A1 to the A2 burdcage style to reduce muzzle flip, or to avoid dust being kicked up when shooting prone?

Quoted: Scanned from one of those Navy SEAL books: images16.fotki.com/v277/photos/2/262472/1782896/SEALscanjpeg-vi.jpg Close up: images16.fotki.com/v278/photos/2/262472/1782896/InvertedA2FSjpeg-vi.jpg I'd say the idea definitely has merit.

Woo hoo - so maybe I'm being super-tactical without even knowing it?  

The A2 flash hider is so short that its contribution to reducing muzzle flip is minimal at best; it vents in three of four directions, and in the standard position does NOT concentrate the venting upward, which would be what you'd need to reduce muzzle flip.  As I read it way back when the change was made, it was entirely to reduce dust signatures for prone shooters.