The fever has hit me and I need a little help! I'am about to get a gun trust and have a few questions!

[Jbremount]

ok....What are you guys putting in the caliber box for the 300 blackout when filing online and with the snail mail paper form 1?

[smustian]

ok....What are you guys putting in the caliber box for the 300 blackout when filing online and with the snail mail paper form 1?

I put 30. Some use .308.

[Jbremount]

Is 7.62 ok?

[Sithlord]

7.62 is a valid caliber, yes.

[rimshaker]

ok....What are you guys putting in the caliber box for the 300 blackout when filing online and with the snail mail paper form 1?

Just plain 300 works also.
Copied straight from an ATF bulletin in Sept 2013:

Calibers in NFA

NFA uses only the ‘base’ caliber for describing an NFA firearm and no ‘.’ to start. For example, we use ‘22’ rather than ‘.22,’ ’22LR,’ .22 WIN,’ etc. Similarly, we use ‘300’ rather than ‘300,’ ‘300 Blackout,’ ‘300 AAC Blackout,’ etc.
For metric descriptions, we do include the ‘.’ when it is internal to the ‘base’ caliber, such as ‘5.56’ or ‘7.62,’ but we do not use the further description to the caliber such as ‘5.56x45’ or ‘7.62x39’ for example.

[Jbremount]

So you are saying, when chosing the caliber for the 300 Blackout, one can use: 300, 308, or 7.62 ? And the ATF will approve either of those numbers and it will work on the tax stamp issued?