Sorry, Herbert, this took a while. Nice to have your help.
Short answer, yes, PJ; the mag tube hole is offset. That is the original design.
That reminds me: Sooner or later you will be playing doctor with it.
There is a SPECIFIC order of steps for disassembly:
Be esp. careful if you disassemble the butt stock from the outer mag tube or remove the lock.
First put lock at half cock and remove both lock screws because the rear one may ride in a shallow slot ON the top of outer mag tube. If so, then there IS a serious contact than prevents stock removal or even sliding it rearward to remove wood pressure on the lock plate.
Do not yet pull the lock to avoid chipping the edges of the wood.
Remove the trigger bar screws, but leave the bar in place.
Remove the butt plate. Then STUDY the nut on the end of the mag tube.
There are two versions that require FITTED slot spanners.
Don't bugger it with a hastily rigged tool because you CAN get it off, but won't have the torque needed without a t-handle FITTED tool when resetting the tube nut.
With a well fitting tool on the mag nut, FIRST try to twist it tighter. You might find it a bit loose, maybe an eighth to a quarter turn from snug. It has to go back THAT WAY because if too tight, the stresses from over tightening can interfere with lock and trigger bar fit in the wood AND in rare cases cycling because the mag tube becomes pushed sideways. NOW you know the FEEL of the nut for later on.
Ok, you can bring it to "contact" when reassembling..
NOW, barely pull the stock rearward maybe a 64th INCH so you SEE a little clearance at the rear of the lock plate and trigger plate. Now GENTLY remove them.
PLEASE READ THE NEXT SENTENCE TWICE:
Do NOT twist the stock to remove it because twisting can damage concealed wood to metal contacts that provide IMPORTANT SUPPORT.
AND if the mag tube is NOT TIGHTLY butted in the receiver, the tube may twist a little tighter and the location of that shallow slot on its outer surface can be lost!
So, pull the stock STRAIGHT rearward IN LINE WITH THE MAG TUBE, NOT THE CENTERLINE OF THE BORE!
NOW don't touch the tube --- LOOK at the outer end of the tube against the rear of the receiver and put a dry marker index mark on the tube : receiver intersection for reassembly reference.
Next, FIRST try to turn the tube DEEPER (to the right) in case it is not butted in the receiver.
Some are NOT tight.
The mag tube MUST go back to the same rotational spot, tight or slightly loose, whichever, SO THAT ANY LOCK CROSS SCREW CLEARANCE IS RESTORED.
If NOT tighly butted and you LATER butt the tube in th3 receiver hole, the rear lock screw slot will be in the wrong location to allow the rear lock screw to align. This WILL ruin your WHOLE DAY. HAHA.
During reassembly test rear lock screw fit and alignment with any shallow screw shank clearance spot with a drill shank of screw diameter.
BETTER if the tube is butted, but the index mark will compensate if not butted.
Do not polish or paint the outside of the mag tube. It is usually a snug pull/push and it has to remain that way.
For first disassembled stocks, BEING CAREFUL TO NOT SNAG WOOD GRAIN/ PAPER THIN SECTIONS OPPOSITE THE LOCK INLETTING, I SLOWLY run a piece of toweling well saturated with boiled linseed oil through the butt stock tube hole, wipe dry with towel patch and let sit TWO days to dry WELL.. A 50-50 mixture of mineral spirits and MinWax urethane does well, too. Each is a sealer. Two days, now or it can stick on he tube later.
I do NOT polish any internal surfaces! Normal use will produce "shiny spots" that can be lightly dabbed w wheel bearing grease.
Oh, yes, as for BLUE LOCTITE on the striker bar SCREWS, there are several old posts here about not using more than will seal ONLY the threads. Letting excess ooze from the threads may cause striker bar resistance.
Use a mainspring vise, NOT channel locks on the mainspring.
Compress it ONLY enough to wiggle loose.
Over compression, so common with channel locks can be nasty.
Be very careful with the vise so the spring doesn't fly out of compression because that causes cracking.
Regards,
Kevin