There are several styles made. The one I make, I have made ? 15-16 of them over the years & prefer the long tang that goes to the buttplate & lips under it, but appears to be all one piece.
I will tell you this is Not for the faint of heart. If ya screw up you can’t hide it & it’s a obvious as the nose on your face depending on the stock, 1/8”to 3/16”’wide & about 3/16” depth.
My long tangs are made then welded to the tang.
Inlet the barrel & original shaped breechplug/ tang, then remove breechplug & add the extension. Next inlet the long tang, the put it all back together & put in stock.
Some cautions:
Once the Tang profile is shaped & inlet, you can’t easily rebend the long tang. You bend it, it grows in length & then won’t fit the inlet. And is dang near impossible to shrink in length.
It is extremely difficult to put in & out of the stock without bending, when all assembled with the barrel because of the total length. Tang will try to hang up & try to bend every time. If it goes in & out easily, you will have gaps in the inletting. You should have to Carefully work it in & out. So it is very tedious. First one I did I did perfect. 2nd one took me 3 tangs as I kept bending it & then it would not fit. So I cut it off & made another new one.
Looking down on it from the top, the top metal is slightly wider than the bottom of it, thus a wide V shape, to help it fit down into the inlet with no gap & appear to grow into the comb.
I built this top rifle in 2009 & took it to CLA & was told by most they had not seen one before.
I remember one builder really liked it & said he would have one in 2010. Sure enough he did & did a pretty good job. I also remember him telling me he would never never Ever build another as it took him 3 weeks just to do the @!*% tang 🤦🏻♂️🫣