Rem 700 bolt handles coming off is not all that uncommon. I have replaced a lot of them.
Having them TIGed is the best way to replace them if put back correctly.... but if you have an acetylene torch one "poor man's fix" that is super strong and reliable works very well. Here is how you do it.
First strip the guts out of the bolt leaving only the bolt body.
1. Drill a #21 hole through the base of the bolt handle where it solders to the bolt body.
2. Clamp the bolt back where it was before it came off. The broken solder joint will fit like a puzzle piece.
3. Run the same #21 bit through the hole you made in the bolt handle so it also goes through the bolt body. In some cases you may have to anneal the rear of the bolt to drill it, but it does no harm. Nothing in the rear of a 700 holds anything but the threads.
4. Tap the holes clear through while still clamped with a 10x32 tap. When done, un-clamp the bolt handle drill clearance through it with a #10 drill.
5. Take a piece of ribbon type silver solder (the type with the 1100 to 1150 degree flow temp) and drill a #8 hole in it so you can clamp the bolt handle to the bolt body with the silver solder becoming the "meat in the sandwich". Coat the ribbon on both sides with flux and screw the handle to the bolt with the solder in between with an 10X32 screw. IMPORTANT NOTE: make very sure the screw is short enough to just grab about 2 threads inside the bolt body so it doesn't intrude into the threaded part of the bolt where you will later have to screw the bolt shroud. It should go through the bolt body about 90% of the way. Allow the thickness of the ribbon solder in your measurements. See what that means in the next step
6. Hold the bolt in a vice and heat the handle and bolt to the requited temperature and you'll see the solder flow. As soon as it does tighten up the screw so the handle is squeezing out the excess silver solder. (this is why you need to have the screw short enough to not interfere with the threads on the inside after you tighten.) The 10X32 will go about 1/2 turn to cinch up when the solder melts.
7. When cool cut the head off the screw leaving the shank of the screw standing up about the thickness of a piece of paper . Pien that down hard with a rounded punch or a small ball-pien hammer so as to hide the joint between the screw and the bolt handle almost 100%, then flush off the joint of the 10X32 screw and bolt handle as you polish up the surface again ............and it's then better then new.
You'll then have it brazed and bolted to the bolt body with the screw threads also being soldered. Far stronger then what Remington did when it was made.
Two major problems with your Bubba fix and a minor problem. As you stated (in red above) how do you expect two pieces of metal tapped at the same time to tighten when the screw is turned? The screw will advance through both pieces at the same exact rate of travel.
Second, while the pieces may fit together like a puzzle there is virtually always some part of the solder that deforms. The two pieces will likely not return to their original locations. The clamping pressure will likely induce further alignment issues.
And the third, minor, issue is timing. If a timing error exists it will be perpetuated. Better to get someone like Dan to fix it.
