I searched the archives, so if this has been addressed please direct me to the link. TY

Building my 1st AR and I purchased (a stated) Mil Spec Spikes Tactical Buffer Tube and MagPul Mil Spec Stock, but it doesn't fit. After some extensive research as to why? I found the Spikes Tactical Tube diameter is 1.25" and not actually mil spec. So Question.

1) Is this design made to not have a Stock (padding only)?
2) Is there a company that sells Stocks that fit 1.25" tube, where, can't find
3) If I just change the tube for a mil spec and use the same spring and buffer, about $35 bucks, am I missing anything from the suggested 1.25 Spikes Buffer Tube

Help is appreciated.

Sounds like you are putting together a felony.

You can’t put a stock on a pistol without it being an SBR.

Some pistol braces may fit your pistol tube.

Switching your pistol tube for a milspec extension will allow the use of some pistol braces and pretty much all carbine stocks.

Hum, well that would not be good, and makes some sense now. #themoreyouknow. Thanks for the information.

Potential to end badly for you, so OP are you up to date with all of CA rule/laws/regulations?  Only ask as you were about to build yourself into a cell.

Are you trying to put a collapsible shoulder stock on a round pistol tube? If so, it won't work correctly.
There are 2 basic types of buffer tubes made for collapsible shoulder stocks, mil.spec and commercial. Both have the extended channel along the bottom for the stocks to pin into position. Commercial tubes are a couple hundredths of an inch fatter than mil.spec. at the circular diameter. Pistol tubes are just round and lack the bottom channel that sticks out.
As was already mentioned, you can't just put a shoulder stock on a pistol. Pistol= barrel less than 16'' long and no shoulder stock. You would need to go through the added hassle with the ATF (acquiring a tax stamp) to make a short barrel rifle, if you want a shoulder stock on a gun with a barrel less than 16''. An arm brace is the closest thing to a shoulder stock that you can add legally, without the tax stamp.
Edit= I noticed you're in California. I don't know all the rules they have out there. You need to check your local rules. The above information pertains only to free American states.