Well I thought I addressed all my questions prior to submitting my form but heres another one......

one the Form 1 it asks caliber.....I filled out everything for a RRA lower, but I am intending to build a 9mm AR SBR. I put 9mm in the caliber field.....should I have put "multi-caliber" in the field or would this null the form......or should I have put 5.56/.223 because that is what was stamped on the lower. Would that have limited me to .223 only? I would eventually like to have different uppers but my primary desire is 9mm.......am I screwed.......am I going to jail, should I jump now, should I sell my wife and kids on the black market to buy more rifles......please advise.....

You are sooooo screwed.  BATF is going to kick your door in and stomp on your kitten.

Just kidding.

It would have been best to put all the possible calibers you might use it in (5.56/.22/9mm/7.62x39/.45) but if you only put 9mm don't worry.  As long as you don't consider it a permanent change of caliber, no one is going to go crazy over it.  For example, one of my M16's is registered in 223 and .22 (thats whats on the F4), but I routinely shot it in 9mm.  If you're really worried, you can write to BATF and ask to amend the F1 to include other calibers.

Shaggy, how the hell did you know about the cat......are you watching me, awe s%$t my phones tapped, honey turn out the lights and move the kids to the basement.......

just kidding. Thanks for the info shaggy. I often wonder about the blast created buy a 7-8" .223 barrel. I am sure it is amazing.

I sit and I wait......for both my 9mm upper from RRA and my stamp from the ATF....

7.5" blast? Sounds like a hollow boom to me, with a suppressor and no ears, I as the shooter hear a sharp crack inside the suppressor, no boom to bust my ears, and the sound of the bullet in flight,,, sounds like a 22LR shot, minus the muzzle "pop", just the "SSSSSHHHHHHEEWW" sound going down range.

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SBR7_11......you lucky bastard you.......I could kick myself in the ass for not buying a preban lower so I could put on a suppressor.......I live in the county and there are plenty of places to shoot except everyone complains about the noise.....I think a suppressor would be awsome for short excursions in the woods....I cannot wait to spend all of me squirrel money.....I have a pretty good idea or what I want to do in the way of an AR 9mm subgun!!!!!! I'm close......

SBR7_11   Whos upper is that.....I've seen a couple from Garrison Mfg and some others but I assume you could have used anyones pistol upper.....?..?...

I'm not so sure about the upper but it looks to me like a DPMS Kitty Kat upper with an American Manufacturing Triple-X suppressor on the end.