Can I put different calibered upper on my SBR lower?

[gunner_lee]

I got my stamp in (mailed 12/4, received 12/7, pending 1/4, approved 4/16) for my .300 BO SBR. The lower is the one with the serial number and engraving. Can I put a different caliber short barreled upper on that lower as long as it isn't a "permanent change"? ex- want to put a 7.5" 5.56 upper on the same lower.) TIA. BTW, I love the blackout SBR- running a 8" AAC barrel/gas block with my YHM Phantom suppressor. Scwiiiiiiiing!

 

[DAVE_M]

Yes.

As long as it isn't a permanent change.

 

[Crimson]

To elaborate, whatever you want to as long as you still have the ability to put it back into the configuration listed on your form.

 

[gunner_lee]

Thanks. The 7.5" 5.56 is awesome! Runs like a scalded cat and I can transition and hit plates out to 200 yds easily with it. Using a Burris AR-332 red dot and there is practically no hold-over out to 200 using the center dot in the reticle. The .300 is using a Primary Arms 2.5 red dot. Their reticle is calibrated to use the dots out to 175 yds with the 220 grain SS or 400 using the supersonic loads.