Yup, but I don't know why anyone would want that. That's how the first grendels came out. And after many people complained of broken x39 bolts they made the deeper type 2 to help improve bolt strength.
well, either that or alexander arms did it to make grendel more proprietary to support their patent. choose your internet mythology. anyways, no intent to hijack thread, just wanted to correct the fact that you can make a grendel gun with an x39 bolt; whether it is the best soln is a different conversation for a different thread.