Hardware and Fasteners - need fastener info

I have a square metal tube approx 3/4 and a smaller tube slides inside to hold a heavy clothes rack vertically. It needs to be disassembled often. There were spring loaded buttons taht popped out when lined up but have worn.
When the hole on the inside tube lines up with the hole on the outside tube I need to insert something that will hold the pieces together yet be able to take them apart.
I have thought of self tapping screws/bolts etc.
The screw, if used would need to be about 1/2" long, the head is not an issue and the diameter of the holes is 3/8 ".
If I cut a ?7/16 self tapper for length, I will lose the self tap part.
Can you think of some fastener I could get at Home Depot instead of ordering an over kill. I have looked around but there are so many things and I can't bring the pieces in the store with me as they are too big.
Thanx alot.

Check out the website below. You could drill the holes all the way through both parts and use a wire locking pin:

http://knobsource.thomasnet.com/category/-categories-pins-quick-release-pins-wire-lock-pins?

Hey, Ken, one question. What happens to your ring pins on your tractor equipment? You know, when you buy 12 of them at the tractor store, put them in all your implement holes, and when you go to hook up an implement, they're gone. These pins you suggest should help Peterr out, but he may consider delrin pins with the push button and detent ball on the opposite end. May can locate them at a camping supply store such as REI, etc. Just an option.

Hey, Larry
You are correct. Tractor pins take a lot of abuse. We seemed to have a lot of trouble with breaking the little chains that were supposed keep the pins from getting lost. Seemed like we were always in a hurry because we were working for ourselves rather than being "employed". Have a great day and stay safe.

:thinker:
Drilling thru is the answer -I have a million options with that concept.
That site has every pin ever made.
Thanx a lot for the help.

Our local blue and white big box store has a section of specialty fasteners in the hardware aisle where the screws and bolts are located. The specialty fasteners are in metal pull-out drawers and include the wire locking pins. Just a thought if you want to go local. A good hardware store would also have these. Good luck with your project.

Thanx for solving the problem. It's amazing the different names of stores around the country.
When I lived smal town we all had a choice of local hardware stores.
Now that times have moved on, and especially being in a big city which I don't like, there are only the big boys or you pay like heck if you can find a smaller one.
I'm all set now tho so thanx again.

Why can't you just replace the snap buttons?

We thought of it but they are poorly designed and extremely difficult to work with in these clothes frames which are constantly assembled and disassembled. The spring loaded button is really a tension loaded device which slips out of place easily.
In my day I bebuilt carbeurators. rebuilt a Seth Thomas clock but this is more difficult than both.
:thinker: