I would like to put one of these together but first a question. On the upper I find some that say 10inch pistol upper while other short uppers do not. Is there a difference between a pistol upper and a short barrel rifle upper. It will be 223 and what is a good lenght 7,9,10 inch or some other lenght. Thanks

An upper is an upper. There is no difference between an upper for a pistol or rifle AR. Do you plan on keeping it as a pistol or later turning it into a SBR? If keeping it as a pistol with no stock of any kind then I would stick with a short barrel such as 7”.

Do keep an eye out on the gas system. They have a pistol gas tube that is really short. There are many 10" barrels that use a regular M4 gas tube.

The shorter the gas tube the harsher it is on the gun.

My 5.56 AR pistol has a 10.5 inch barrel with a carbine length gas system. The longer gas tube, increased velocity and, in my opinion, the better overall look of the 10.5 barrel vs a 7, were my factors in choosing the 10.5 for my 5.56 pistol build.

Now, my 9mm AR pistol has a 7 inch barrel and no gas tube since it's blowback operated. I put a shockwave blade on both of them and they are blast to shoot. I've had no issues with either so I can't comment about which is a more reliable system.

What are you starting with for lower? Was it a rifle at purchase or a stripped lower registered as a pistol or other.

I've always had my ffl put my stripped lowers as "other" and you can build whatever you want. I've never purchased a dedicated pistol lower, so I don't know how that would be transferred.

Thanks for all the info. I will be starting from nothing so all the ideas are great.

quote:

Is there a difference between a pistol upper and a short barrel rifle upper.

Only the paperwork (tax stamp) for the lower it's attached to.