buffer tube puzzle?

[nekshot]

Can a pistol buffer tube be used for a rifle type stock? What happens if the springs get mixed up as a rifle ty pe spring in a carbine tube? Or a pistol spring in a carbine tube? I know I am a little slow on things and I simply need to know why such and such must be this way. This ar bug has really got my mind dreaming up all sorts of things. I was thinking you could make a pump action out of one so I did it. I have it all together and it works good. I am finishing the parts then we will put it all together and see if its better than my amish machine gun(760 remmy in 35 rem). I have plenty of ideas but meds and fixed income keeps me close to the house!

[244]

You must be careful when changing stocks on an AR, but this MAY have changed with the introduction of the SB Tactical SBA3 pistol brace. It uses a mil-spec diameter carbine length buffer (receiver extension) tube and mounts on it with 5 usable positions (one adjustment position is lost). It will look much like a SBR, but it is a pistol with the brace attached.

I believe the ATF has stated that an AR assembled or transferred as a RIFLE must be registered if it is modified to a PISTOL configuration. If the receiver was transferred as a pistol or "stripped", then it can be assembled as a rifle or pistol, but once assembled as a rifle, it is illegal to configure it back to a pistol without registration. Clear as mud, right?

An AR rifle length buffer spring is about an inch longer than a carbine length buffer spring. You will likely have cycling/function issues if you install a rifle length buffer spring in a carbine/pistol length buffer tube.

[nekshot]

Ok, Thanks for your explanations. So i should keep carbine tube and spring together, and keep rifle tube and spring together. I do not get the pistol deal with an ar so thats no issue with me. I see tubes with 6 positions also. What is the advantage of carbine or rifle tube?

[popper]

Real pistol (legal) doesn't have a screw hole in the back. Normally uses a carbine spring but some are special. Some use a carbine tube but ream the threads so aft can't claim is could be sbr.

[244]

Real pistol (legal) doesn't have a screw hole in the back. Normally uses a carbine spring but some are special. Some use a carbine tube but ream the threads so aft can't claim is could be sbr.

Look at the SB Tactical SBA3 brace and the included mil-spec carbine buffer tube. It is the same buffer tube as would be used on a carbine (or SBR) with a collapsible stock.

https://www.sb-tactical.com/product/sba3/

A rifle length buffer tube does have a threaded hole for attachment of a fixed buttstock, be it A1 or A2 length (with spacer), but the hole in a carbine buffer tube is simply a weep hole.