Definitely slotting the tenons. I should have replaced the supplied pins with threaded rod, now that you mention it. Probably would have gripped better. Oh well. When I do it the third time, I will up the game even further.When repairing structural cracks or making butt joints in stock forearms I avoid the wood glues and Gorilla Glue, though great adhesives. If the crack or seam opens up again from stress these glues will not adhere to the old cured glue. You generally have to remove all of the old glue from the joint, a real PIA. Accuraglass or similar on the other hand will adhere to old repairs and allow you to build up the repair area if needed. Just what I have experienced.
Here are photographs of a repair I did to a 100 year old stock (it was made in 1917). Little bit different to say the least, but the concept uses multiple small thread rods for maximum strength and grip. I was able to square up the splice area and add a new piece of wood (it was difficult to get a close match). The splice is hidden under the metal ring in the second photo, but it’s very strong and the stock has seen about 2500 high power rifle rounds, among other abuses, and is as good as new.
Now if you never knock the stock over without the barrel in place or stress it in some other way (you have or will slot the pin holes in the barrel tenons, correct) you can get away with less reenforcement, I’ve just reach the point of wanting to do things once. Over killing a bear isn’t a bad thing, but under killing one sure can be bad.
-Red, underkilling bears one at a time…