I made a handful of these a while back and after I stopped selling parts to others, I put the remaining ones in storage. I found them the other day and put them up for sale on a gun forum, not thinking there was any real demand for them. I sold out in about five minutes.I guess since they turned out to be popular, I will make another run of them. They are original ID and OD, and have a shoulder for welding to the receiver so you're not welding on the threads themselves. They're about an inch long overall.
Here's what they look like.
Here's one with the cap screwed on. Cap NOT included.