So I gambled and purchased the upper from Centerfire Systems
https://www.centerfiresystems.com/p-...num-black.aspx

It does break Clay's when you do your part.

The website does say use shells 2.25" max for reliable function. The shells they recommend are not available anywhere and no companies list their true OAL. I was able to single load some Winchester AA and it fired nicely.

The barrel nut was not installed tightly and the hardguard wobbles. Allen set screws hold the hand guard on and 1/3 stripped out so some drilling is in order to remove the setscrew.

Recoil is near non existant, there is some type of spring mechanism around the barrel under the hand guard.

So far, unless you are willing to work on this upper and buy different brands of 410s to find 1 that will work I am going to recommend avoiding the upper.