Boy, that’s an unfortunate crack on a new build.
Personally, not a fan of fasteners like Super Glue or Tite Bond for repairs of the type of crack you have. In a non stress area, they work fine, but something is stressing your stock. Problem I have with Super Glue and Tite Bond is while they can hold a repair, when they fail, they do not bond to old repairs of the same, while a product like Acraglas and similar products are made to bond to itself. Learned this the hard way.
As others have suggested, I would start by removing the JB Weld, then bed the breech plug (make sure you have at least .010” clearance at the end of the tang) and breech area of the barrel with something like Acraglas. With the amount of wood you have removed, it will require some creative damning to accomplish, but very doable. I also agree with the tang screws not touching any wood (or bedding).
On to how to strengthen the stock. I have repaired quite few stocks with similar cracks, though mostly Milsurp stocks. Below are photographs of a 100 plus year old stock with a similar crack (unfortunately I do not have photographs of other stocks that were much worse) that I reinforced with a threaded brass rod. Ugly and visible, but effective. Basically, after the above steps are taken in an attempt to eliminate the cause, a threaded rod is run across the crack through the stock. I drill a hole that allows for about 70% threads, and use the threaded brass rod (10-32, coated with Acraglas, in this example) to cut the threads in the stock. I have seen similar reinforcements from years ago. Seems to work. The stock in the photographs has endured nearly 1000 high power centerfire rifle rounds without failure to date.
Above might be overkill, but with the wood you have removed from the stock for the aftermarket lock, doubt you will get a replacement stock under warranty on a kit gun.
And yes, my repair will require a stock refinish, not much different from the finishing process you just experienced. But I believe it will fix your problem.
