AR pistol 10.5" barrel question

[USAF_Vet]

I'm building an AR pistol, and have decided on the 10.5" barrel.

As a pistol, I know the 10.5" barrel is ok per state and federal laws. The reason I'm building this as a pistol first is the pistol-->rifle--->pistol configuration change.

Anyway, to save a bit of coin, I'm thinking of buying the one upper with 10.5" barrel, and a 5.5" muzzle device instead of a second 16" barrel or barreled upper.

So here is the question: Does the 5.5" muzzle device need to be permanently attached (pinned and welded) to the 10.5" barrel when in it's rifle configuration?

If not, then a simple stock and muzzle device change to convert back to a pistol is cheaper than swapping out the barrel, or the entire upper.

If it does need to be permanently attached, then I'm back to buying either a separate barrel, or another upper.

 

[Sam1911]

Yeah. If it is a RIFLE, then it has to have a 16" barrel, per the guidelines the ATF has published regarding permanent attachment of whatever muzzle device.

If you wanted to register it as an SBR, you could do what you're talking about, but I understand that isn't your point.

You're back to building a 2nd upper for "rifle" config.

 

[USAF_Vet]

That's what I needed to know, the brake must be permanently attached for the rifle configuration. So I'm looking at a complete second upper if I want to swap back and forth from pistol to rifle.

 

[Tirod]

Not necessarily.

There are vendors who sell a fast change barrel nut kit which allows swapping barrels more easily. Just avoid the short barrel + stock combination and you're good.

Hopefully no one will jump in with "constructive intent" because every AR owner with a complete pistol and rifle would qualify - so dear readers, just don't go there.

Anyway, some links: https://www.mapartsinc.com/shop/details.asp?id=1415

https://www.coppercustom.com/shop/parts-kits/dolos-ar15-quick-change-barrel-system/

It can be done. A lot talk about it, but it seems there are very few pics of them. I'm thinking it happens a lot less than we discuss it.

One finesse point is that the optic on the upper may need separate zero settings for the different barrels. Given the different purposes of the barrel lengths having them pre-zeroed and swapping two back and forth then leads to just leaving them on their respective uppers, and then you notice a few years later they grew their own lowers.

Its a mysterious phenomenon repeatedly posted by long term builders. My pistol build seems to have grown out of a single clamp on FSB I had lying around.

 

[MistWolf]

Put your 10.5 inch upper together as a pistol and go ahead get a second rifle upper- or better yet, a complete second AR as your budget allows. Skip the permanently pinned muzzle device scene. The shorty is a pile of fun, especially with a Sig arm brace.

From what I understand, there are laws in Michigan that are different from other states. I don't pretend to even know what they are and will assume you have made yourself aware of how they apply to your project and will leave it at that

 

[Warp]

One interesting aspect to MI law that may be relevant to him is that you cannot have a loaded rifle in your car, but you can have a loaded pistol (with carry license), and if my understanding is correct, you can even have a loaded SBR. I'm not totally sure the SBR part though, double check...but I do now that a short upper'd AR that is legally a pistol with a sig brace can be carried in your car but a regular old 16"+ rifle cannot.

Buuut then MI registers all handguns so you would hvae to register the short upper'd legally a handgun AR with the state, and you would not have to do that with a 16"+ rifle.

FWIW