Odd happening on 10/22

I have a SS heavy barrel 10/22 in the tan laminate wood stock. I had Brimstone do their 'best' trigger job and new trigger install; I'm happy with it. Several years ago (just thought about posting this today) I borrowed a buddy's factory original 10/22 trigger assembly (he went to a BX). I wanted to have a spare in case my Brimstone mod. went south on me. I decided to check out the fit of his factory orig/borrowed assembly and, lo and behold, the holes for the pins did not match up. I couldn't install it. Now, to my way of thinking, this aberration shouldn't exist. I assume that any 10/22 trigger group/assembly should pop in to ANY 10/22 ever made. It's been awhile since I tried this, or even took my 10/22 apart so I can't remember if the trigger group is metal or plastic, but I think mine is plastic. Can anyone give me some info/insights on this misfit ???
THANKS,
John

Nope, like you said, ODD.

Even the 10/22M used the same trigger housing as the LR.

When I was looking for a spare used 10/22 OE trigger assembly I found some photos and follow-up information that leads me to believe that there were some differences in -early- trigger housings that would make for problems trying to fit them into -late- guns. If I remember right, the heavy/thick boss just to the rear of the trigger ring -may- be longer on earlier models, the later trigger housings -could- work (BX ?) in an earlier gun, BUT, early housing into a later period production MIGHT be a difficulty.
I -might- be commenting out of my hat, but the problem could possibly be verified by someone who has a collection of 10/22s that included guns with both the metal -and- 'late'plastic trigger housings.

The manufacturing tolerances were a lot looser on the old metal trigger housings. If you want to order a trigger upgrade kit from Tony Kidd, he won't warrantee that it will work in a metal housing. It MAY work, or it may NOT. But it always works in the polymer housings.

I've done some 'mix and match' trigger replacement w/o any misfits.

TestEngineer said:

The manufacturing tolerances were a lot looser on the old metal trigger housings. If you want to order a trigger upgrade kit from Tony Kidd, he won't warrantee that it will work in a metal housing. It MAY work, or it may NOT. But it always works in the polymer housings.

Click to expand...

I think that 'may-or-may not' has to do with side clearance for the hammer. There seems to be hammer pivot boss thickness differences, and that carries over to aftermarket trigger assembly parts. I don't know if hammer side clearance can even be shimmed (-or- might even ever be neccessary), due to it being sorta' close in there, and messing with hammer, spring, and any sort of shim would prove to be miserable. Slave pins, tailored for a specific purpose would more than likely be required.
It seems as if every 10/22 type of fire control owner should be able to source the 'retainer' that Ruger packages their 'BX' trigger assemblies with, just so that working on one of these guns doesn't result in pins sliding out when the trigger assembly is removed from the stock.
Glad I have one now.

Volquartsen supplies a couple of shims with their target hammer, but again they only account for manufacturing tolerances, not a design difference.

Big difference between a complete housing that won't fit and a design change in the hammer.

I have never seen a 10/22 trigger differ in mounting than any other. Maybe take some pics if you can borrow the same housing again.