A buddy has an older pistol that is probably 20 years old, he finally had enough gunk built up that it really needed to be taken apart to get the gunk behind the recoil spring assembly.
It was very hard to get apart and almost impossible to get back together, looking at the score marks on the bolt stop and the hole itself it appears that the upper and lower are slightly misaligned.
The pin fits through the upper and lower when separated but not when assembled, it would not go all the way in from the top either but would jam at the lower.
Tried several times by taking apart but the alignment seems to be off to one side, only a couple of thousandths.
Would a proper sized drill bit be considered WECSOG? The lower hole is only a tiny bit off and I thought SLOWLY going in from the top would align the holes properly.

In summary, the bolt latch goes in at a very, very slight angle and when it gets to the upper hole it will not go in without hammering on it, bolt stop had score marks on one side.
I have a couple of Ruger .22 pistols and have no issues with them, he lives too far away for me to have run home to try swapping parts.

yeah, they suck to reassemble....that's why I have no other Ruger automatic...I got revolvers though!

Read the instruction manual.  There is probably a youtube video on it too.


Brownells sells a part that makes this easier for those who won't read the directions.

The barrel assembly has slide either forward or back on the lower frame. The holes are misaligned because of this.  Use a rubber or other non marring hammer to tap it for and back until it lines up.  

The Mk I has always been a PITA to re assemble. Make sure the barrel receiver are fully forward on the pistol grip. Drop the hammer and make sure the hammer strut fits into the recess in the take down piece. It might seem impossible at first but it will drop right in after a while.

The grip frame and receiver holes are aligned by tapping on the rear of the receiver or muzzle with a nylon mallet.  After you do it a dozen times or so, the parts will loosen up.

It's simple one you do it a few times
https://www.youtube.com/results?search_query=ruger+mkii+disassembly

Had two of them.  The first was a standard 6inch Mk2. Sold it and
bought a 22/45 with a two inch barrel. Both were a royal PITA to
reassemble. Sold that one too.  

Bought a Browning Buckmark with another 2 inch barrel.  Three
screws and the thing comes apart no problem.

Life is much easier, except for the .22 ammo problem.

I have no problem taking apart and assembling Ruger .22 pistols, it is only this particular one where the grip frame hole does not line up properly with the receiver holes, the receiver is ROTATED in relation to the grip frame.
Back and forth does nothing since the gouging is on the side of the bolt stop, not the front or rear.

Remove barrel from lower frame.
Apply file to appropriate inside of lug so that it rotates the way you need it too.  Center punch and or raise or add metal to the other side.
Assemble shoot.

I wouldn't take a file to anything until I looked closely at the frame lug and matching area on the receiver.  Filing parts is irreversible in this case. Unless you know where the issue causing the misalignment is, you are taking guesses how to remedy it.

Do you have really good pictures of the hole misalignment, frame lug area and matching frame lug area on the receiver?

I se to think my MkII was a PITA to take down until I learned how to do it right. Since then no issue at all and no screws to get lost, just big easy to clean parts.

I took mine to my smith after struggling to re-assemble mine. He struggled and ended up taking a small amount of metal off. It is still REAL tight but he said it would loosen up and he didn't want to take too much materiel away. He still used a dead-blow hammer to reassemble. It hasn't been apart since.