If I get a .556 lower does this mean I’m stuck with that caliber?

[DW357]

I’ve got this 22lr upper on my SBR and it is AWESOME. Super well made and very accurate.

Nordic Components AR-15 22RB Pistol Upper Receiver Assembly 22 Long

Nordic Components’ 22RB dedicated 22 upper receiver converts your standard AR-pattern lower to a dedicated .22LR for recreational shooting,...

www.midwayusa.com

 

[1919FAN]

350 legend ammo is still on the cheap side .

 

[paul73]

350 legend ammo is still on the cheap side .

at $1.85 a round? heh?

 

[1919FAN]

at $1.85 a round? heh?

Do your homework I pick it up regularly at Wally world for under 12 a box.

 

[Duxprep]

Uggg hahaha ...... still to early in the am sorry guys just had our third kiddo brain is not all their rite now

Put whatever you want on it unless it's NFA - and congrats on the baby!

 

[MGnoob]

they say - "Works best with round-style AR-15 hammers; notched hammers can cause function problems."
is the problem real? as i got a 3lb pull larue trigger i love, not going to alter that, but, it is notched.

It basically could be made to work with anything. It takes a little hands-on experience for you yet how to make it work properly. Log on the CMG website and look at the accessories. I initially ran mine F/A but typically I run it Semi now....The biggest issue with function I ever ran into is if you dont occasionally oil it or clean the spring under the firing pin in it either won’t work or fires runaway F/A...

 

[MAGA99]

i kinda play with the idea to make an upper for a soviet 7.62×39 round, but, not sure if it is really worth the time.
a 300blk i would want to do as well, i want it - but prices and availability of 300blk now are both insane. so, it will wait.

300 blackout only thing different is barrel, same BCG, magazines, etc.

x39, barrel, BCG, magazines all different. My buddy has one and it’s fun to play with. We’ve had no issues playing with it but allegedly there can be reliability issues with those proprietary magazines since they’re curved, but have to be straight to fit in the AR lower mag well. Think of an AK magazine next to an AR magazine....then cut the top off the AR mag and weld it onto the bottom half of the AK magazine.

 

[240Geezer]

i kinda play with the idea to make an upper for a soviet 7.62×39 round, but, not sure if it is really worth the time.
a 300blk i would want to do as well, i want it - but prices and availability of 300blk now are both insane. so, it will wait.

300BLK is pretty much plug n play. Use the right upper and it even works with 5.56 mags.
X39 will need a little tuning.
Suggest the heavy hammer spring and extended firing pin. Steel case ammo needs a good whack on the primer.
Also special mags for the more tapered roosky round otherwise you’ll have feeding issues.
I have 3 AR’s chambered in x39.
2 carbines and a pistol.
Build 1 works great.
Build 2 has some chamber issues I’m sorting thru.
Build 3 (the pistol) has not been fired. Yet.

 

[PappyM3]

But typo aside, yes you're good assuming its not an NFA item

Even with NFA, you can swap to your hearts content. They just ask that you maintain the ability to convert it back to the configuration on the form. You can also add a configuration addendum with a list of all the caliber/barrel length/overall length configurations it might be in.

 

[PappyM3]

I’ve got this 22lr upper on my SBR and it is AWESOME. Super well made and very accurate.

Nordic Components AR-15 22RB Pistol Upper Receiver Assembly 22 Long

Nordic Components’ 22RB dedicated 22 upper receiver converts your standard AR-pattern lower to a dedicated .22LR for recreational shooting,...

www.midwayusa.com

That is pretty sweet.

For anybody wanting a dedicated 22lr upper, but want to build it themselves, RightToBear.com .22LR Rifle Parts, Upgrades & Accessories has a lot of 22lr AR components, both CMMG and their own branded parts.

 

[Spanz]

you shoot .556?
That's tiny!

 

[PappyM3]

you shoot .556?
That's tiny!

Actually, that’s HUGE.

Add 0.056” onto the big one below:


Unless he said “.556mm”

 

[Drix]

.556 will either be tiny, or illegal

But typo aside, yes you're good assuming its not an NFA item

Even if it is a nfa item you can adjust the caliber, you can have a multicaliber by specifying it in box 4h.

If you've already paid your tax stamp you can send a letter to the ATF describing which uppers you are planning to use with the your SBR. When you send a letter to the ATF, send it in duplicate and request a letter back from the ATF confirming that received/approved the letter. What you need to include in the letter is the make, model and serial number of your lower, who it is registered to, the caliber and OAL (overall length) of the new uppers that you want to add to the SBR.

 

[Spanz]

Actually, that’s HUGE.

Add 0.056” onto the big one below:
View attachment 470584

Unless he said “.556mm”

Perfect round for home defense!

 

[PappyM3]

Perfect round for home defense!

Or your neighbor down the street’s home defense!

 

[Spanz]

Or your neighbor down the street’s home defense!

or the next county.

 

[AJK129]

Or your neighbor down the street’s home defense!

For defending against homes

 

[Spanz]

For defending against Holmes

FIFY

 

[paul73]

For defending against homes

armored vehicles and helis.