Florida Shooters Network

What is the difference between a lower designated as "Multi-cal" to one that is for 223/556?

Not a darn thing but the inscription. Manufacturers didn't want to lose potential sales from customers who want to build a .300 Blackout or some other rifle that uses the standard 223/556 lower, but didn't want their custom job inscribed with 223/556.

Now, if you have a lower marked "Multi-cal" and you apply for a tax stamp for an SBR, ATF wants you to put the intended caliber in the application, not Multi-cal. So if you plan to slap a 10" upper in 5.56 on a Multi-cal lower, you need to put 5.56 on the Form 1.

Thanks; that's what I thought but wasn't sure.

Odessaman wrote: ↑Wed Dec 18, 2019 5:58 pm ... if you plan to slap a 10" upper in 5.56 on a Multi-cal lower, you need to put 5.56 on the Form 1.

Am I correct in my understanding that as long as you retain possession of the upper that matches the information on the approved Form 1 and it can be readily re-installed on the lower, then you can swap out any other upper you wish?

flcracker wrote: ↑Thu Dec 19, 2019 10:33 am

Odessaman wrote: ↑Wed Dec 18, 2019 5:58 pm ... if you plan to slap a 10" upper in 5.56 on a Multi-cal lower, you need to put 5.56 on the Form 1.

Am I correct in my understanding that as long as you retain possession of the upper that matches the information on the approved Form 1 and it can be readily re-installed on the lower, then you can swap out any other upper you wish?

Yes, that's correct - once you get the stamp and get the lower properly engraved, you can swap back and forth among other compatible uppers.

Yeah most if not all new lowers sold no longer include any caliber indication on them.

It was never anything more than a "the upper assembly on this is supposed to be..."