Dtech DOES make AR10's. I'm picking up my new LR308 in about a week which will be the second AR I've purchased from Mike in less than 1 year. My first was his 25 DTI. I'm in love with that thing!!
I too thought Dtech only made AR15's until one day (about 5 months ago) I spoke to Mike. He said that rumor started several years ago when somebody incorrectly posted on a forum that he only built AR15's. That was bad information and today the misconception still lives on.
In the time that I've known Mike, I can't say enough good things about his support!!! There was a little 'dust on my bottle' so-to-speak when it came to reloading using 7/8 X 14 dies. Mike continually helped me pinpoint the things I was overlooking or doing incorrectly. His depth of knowledge is STOUT. In the end; everything Mike told me in the beginning was fact, fact fact!!
The 4 month lead-time is based on barrels not being in stock. If he has the barrel the wait time could be a lot less. He does not do any other gunsmithing like bolt rifles etc.
You won't regret getting one of his AR's.
Hope this helped.
Kahuner