Class 3 questions

[WDE91]

I realize I will not be able to own what the types of guns I have questions about but I still have the questions

SBR like an AR15
The stamp is on the lower correct?
Can different uppers of a variety of lengths be put on that same SBR'ed lower?

SBS, like an 870
Can different barrels of different lengths be put on the shotgun?
IE have one 870 to do everything
14" home defense setup and then switch that barrel out to a 28" to go bust clays?

Thank you for your help
Joseph Kearns

[OCArmory]

You can temporarily change the dimensions of your properly registered SBR or SBS. If you make the change permanent you need to notify the ATF.

[EBR Works]

Works for AOWs as well