I am now making and selling SC feeds. Both cram and jam for 10rnd tubes and feed tubes w/ CCI feed gates.
Pics of the cram and jam

Pics of feed tube with slots (picture it with a CCI feed gate

) These can be made any length desired. This is a 10rnd version.

Will fit on a 7/8" feedneck or inside a clamping feedneck with a spacer. Price is $10 shipped and they use a steel locking collar. These are for the people that aren't do it yourself'ers. They are easy to make and if you'd like to know how, PM me.
No pics yet of the actual tube one but it is the same as above with any legth tube you desire. Tube will have windows milled in it and a CCI feedgate. $27 shipped