Block 4c on form one question

[hardcase]

I am about ready to send in a Form 1 for another SBR. The first one I sent was last summer. It had 5.56 on the lower and that is what I put in block 4c "(caliber or gauge (specify one)" a quote from the form. It went through without a hitch.

The one I'm working on now has 5.56 on the lower and I'd like to put 30 cal in block 4c. Will this create a problem?

[steven11b]

No it won't be a problem. I used 300 from the drop down box when I did my blackout lower. The ATF requires that the caliber be marked on the weapon someplace and most manufacturers will mark the barrel with the caliber.