I'm also using modified 1 1/2 inch sewer test plugs in the ends for spikes as limiters.
Originally Posted by GroundHog
This is what I used. You can get them at Home Depot or Lowes.
Remove the stock bolt and wing nut, buy a longer carriage bolt and nut.
Put it back together using the longer bolt and the nut in place of the wing nut.
Grind the end of the bolt to a point.
Put the plug in the end of the tube snug the nut up until the plug is tight in the tube, then you have a spike to stick in the ground to keep the leg from kicking out.
This also keeps the tube from filling up with dirt or mud.
You can leave them in or take them out when you take it down. I take mine out because I don't want to poke anything with the point, plus they make the poles a little too long for the bag.
GroundHog's images of the "plugs" ( page119 post1183 of the TurtleDog stand thread )