Multi Cal Stripped Lowers?

I'm noticing that most of the less expensive stripped lowers that I'm finding are marked multi cal. What is the difference between one marked 5.56 and one multi cal. Is it better to get a 5.56 marked lower for fit? I'm really itching to get a lower to complete my first build but I want it to be quality. Thanks for whatever you can offer.

YJ

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Originally Posted by yjsaindon

I'm noticing that most of the less expensive stripped lowers that I'm finding are marked multi cal. What is the difference between one marked 5.56 and one multi cal. Is it better to get a 5.56 marked lower for fit? I'm really itching to get a lower to complete my first build but I want it to be quality. Thanks for whatever you can offer.

YJ

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No differences, except one's marked "5.56" or ".223" and one's marked "Multi"

The multi caliber is important if you are going to register the receiver as an SBR. It gives you the ability to shoot whatever calibers you want out of it. The ATF might have a problem shooting 9mm out of an .223 or 5.56, title 3 weapon.
I will go out on a limb here on this but................ If Congress ever requires 50-BMG rifles to be registered your Bohica, Safety Harbor, whatever brand upper will need to be on a multi caliber labeled lower or it won't be register-able due to the .223/5.56 discrepancy.
This is my best guess on the 50 BMG reasoning. I have know actual knowledge of how a Brady gun grabbers mind (if they actually have one) works.

Bottom line for me, any new AR lower that I buy must be in "multi" caliber.

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Originally Posted by Javelinadave

The multi caliber is important if you are going to register the receiver as an SBR. It gives you the ability to shoot whatever calibers you want out of it. The ATF might have a problem shooting 9mm out of an .223 or 5.56, title 3 weapon.
I will go out on a limb here on this but................ If Congress ever requires 50-BMG rifles to be registered your Bohica, Safety Harbor, whatever brand upper will need to be on a multi caliber labeled lower or it won't be register-able due to the .223/5.56 discrepancy.
This is my best guess on the 50 BMG reasoning. I have know actual knowledge of how a Brady gun grabbers mind (if they actually have one) works.

Bottom line for me, any new AR lower that I buy must be in "multi" caliber.

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Nope. Marked caliber does not restrict what you can shoot out of it, just reflects the initial configuration.

FWIW, ATF no longer accepts SBR registrations with "MULTI" as the caliber, since they want documentation of the rifle AS YOU ARE GOING TO BUILD IT.

So you can still build an SBR using a lower marked "multi" but when you send in the Form 1 you have to write in a specific caliber as you plan to build?

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Originally Posted by Circuits

Nope. Marked caliber does not restrict what you can shoot out of it, just reflects the initial configuration.

FWIW, ATF no longer accepts SBR registrations with "MULTI" as the caliber, since they want documentation of the rifle AS YOU ARE GOING TO BUILD IT.

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I stand corrected on the "multi" part. I still stand by my 50 BMG upper theory though.

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Originally Posted by Circuits

ATF no longer accepts SBR registrations with "MULTI" as the caliber, since they want documentation of the rifle AS YOU ARE GOING TO BUILD IT.

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Originally Posted by Stuart

So you can still build an SBR using a lower marked "multi" but when you send in the Form 1 you have to write in a specific caliber as you plan to build?

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If that's the case and someone has 4 different caliber uppers, when they register teh SBR, do they have to register four different times?

No, but if you are already planning on using four different calibers, you'd just write ".22lr, 9mm, 5.7mm, and .223" in the box as I understand it.

Yes, you can still use a lower marked "multi" to make an SBR.

You list the initial caliber in the caliber box.

If for some reason you want additional calibers listed, those go in the additional description box.... not necessary, but you can do it.

Big Bear: no - one registration. If you change uppers and calibers and barrel lengths, it doesn't matter. ATF requests that if you permanently change the basic configuration (say, you registered it as a 12" .223, then sell off all your .223 uppers, so now you only have a short .22lr and a short .40S&W upper for it), that you notify them of its new "default" configuration.