Help me figure this out Carbon 15 pistol to 300blackout

[morris]

So I am 3 months into waiting on my SDN6, last set of form 4's to my dealer took a bit over 4 monthsl, it will go on a hkmr556. While I am waiting I had an idea, well someone made a suggestion at a local shop and I kind of added on to it.

I have a Bushmaster Carbon15 on top of my refrigerator, its a pistol. I was thinking I could put a 8 or 9 inch barrel on it and then use my AAC eveolution 9 on the end of it. The Evolution 9 is a few versions old I think but I believe AAC might upgrade it for a fee.

So I have two options send the carbon 15 to a gunsmith and let them do it at a probably inflated rate, or maybe I can do it myself. How hard is it to swap barrels, do I need to do anything with the buffer or gas blocks? Im kind of new to AR's so any help would be appreciated.

[txwin70]

It isn't difficult to change out an AR-15 barrel. The correct tools make the job real easy. There are youtube videos all over the internet on how to do it. I have done more than a few and haven't had one fail yet . I recommend a plastic flipper for the upper, and an armorers wrench. A decent punch set and brass hammer and your all set.

[morris]

Does anyone know if I can just slap a 9" AAC upper on the pistol lower and go for it? I am new to AR's and I have a shop that wants to build the carbon 15 into 300 blackout using separatencomponents but it seems another option is for me to just buy a 9" upper.

[Dogtired]

If its a pistol, pistol length barrel is allowed.

[morris]

I meant will the 9"upper fit on the lower without any modification ie will it drop in.

[txwin70]

spoke too soon.

[-k-]

It uses a non standard carrier, spring and buffer. There is no way to know if a barrel or upper designed for the standard system will work right with them.

I recommend people who want to build a pistol AR use a system that uses a standard full size spring.

[82nd airborne]

It uses a non standard carrier, spring and buffer. There is no way to know if a barrel or upper designed for the standard system will work right with them.

I recommend people who want to build a pistol AR use a system that uses a standard full size spring.

Not to mention a different barrel nut and extension specs.
It looks like an ar, quacks like an ar, and smells like an ar, but its not an ar.

[morris]

That's the information I needed thanks so much everyone! This is one of those times for me anyway I just want it to work, so I'll drop it off let them do what they want and pick it up completed.