What is none mil spec on the buffer tube, like an RRA lower. Will stocks like the Magpull m93 not fit?

The aftermarket tube are bigger (diameter), milspec stocks (Crane, Vltor) will not fit on them...

The Magpul M93 uses its own special tube anyway, so its going to be different than all the others.  Stocks like the VLTOR and LMT SOPMOD use the mil spec buffer tube.  CMT and Colt tubes are mil spec.  

OK i may have miss worded it. Is the threads in the RRA lower bigger,or just the tube. Could the tube be replaced with one that is Mil spec? I'm just looking for the closest to Mil spec.

just the tube agter the threads.  All reciver extensions (aka buffer tube) use the same thread.

Do you know why you are looking for something different than what you currently have?

To answer what I think you are asking, the lower receiver is the same on all of them.  

Do you know why you are looking for something different than what you currently have?

I don't have any lowers now.Just saw out of spec buffer tubes in a post, when i was checking out RRA stuff.

Looks like RRA is gtg, just need to find good barrels now.

I wouldn't get worried about the buffer tube, get the weapon that you want.  Your weapon isn't going to be milspec no matter what you do.

Receiver Extension Tube 101

The threads for the tube are the same in all lowers (or should be anyway). The tubes for telscoping stocks are different, the milspec tubes are 1.150 iirc and the aftermarket tubes run all over the place, but are generally around 1.175 or so...

When Dick Drasen was making the aftermarket copy, he used this slightly oversize tube and it has become the de facto standard in the industry. The reason is mostly the production technique and associated cost -- a milspec tube has the threads cut and then the body is reduced by "shaving" or planing along the length of the tube with a special cutter... you can get an idea of how this is done by looking at an LMT tube, the cuts are made in three passes and the LMT process does not blend each cut perfectly, so you have those two "ridges" the run the length of the tube at about 2 and 11

The aftermarket tubes do not reduce the size of the body... but this does NOT mean they are stronger, if fact, because the threads on the aftermarket tubes are generally not cut to full profile, they are demonstrably weaker -- this is one of the first places you will see a rifle break.

Rifle tubes are all in the same box... and the Magpull is out by itself.

Wow im glad someone asked.  I was seriously considering buying a VLTOR mod stock for my 16" Bushy.  So will it just "drop in" or am I going to  have to modify something?

Quoted: Wow im glad someone asked.  I was seriously considering buying a VLTOR mod stock for my 16" Bushy.  So will it just "drop in" or am I going to  have to modify something?

the Vltor will work fine, but not with the receiver extension tube the they use... Vltor kits come with a new receiver extension tube, spring and buffer and the job of changing the out is simple, or cheap to have done at a shop... your choice

thanks Gunzilla.  Ive only been in this hobby a year and im still learning.  Im glad when someone asks a ?? I have been wanting to learn myself.

Quoted: thanks Gunzilla.  Ive only been in this hobby a year and im still learning.  Im glad when someone asks a ?? I have been wanting to learn myself.

oddly enough, that last post reminded me that I had to put a new tube and stock on a rifle... I just sat down from doing it, it takes that long (minus letting the dog out to pee).

eta: welcome to the world, I havn't been at this too long myself