neutered sight that came on my 49/50 debate gun:
front edge of rear pin to face of sight: 50.6mm
front edge of front pin to face of sight: 4.5mm
offset between the two:46.1mm
Russian 50 sight I used for a replacement:
front edge of rear pin to face of sight: 51.0mm
front edge of front pin to face of sight:4.7mm
offset between the two: 46.3
no lightening cut Chinese/Russian?:
front edge of rear pin to face of sight: 51.5mm
front edge of front pin to face of sight: 4.8mm
offset between the two: 46.7
front edge of rear pin to face of sight: 51.1mm
front edge of front pin to face of sight:4.3mm
offset between the two: 46.8mm
Random assumed Chinese poorly neutered FSB:
front edge of rear pin to face of sight: 51.7mm
front edge of front pi to face of sight: 4.7mm
offset between the two: 47mm
While these measurements were brought to you buy Pittsburgh Tool and Harbor Freight, they clearly show the amount of difference I was talking about above the averages of other sights tested. Especially of note should be the early 50 replacement difference vs. the original one on what I am calling a 49 for now. That was what I experienced fitting the early 50 sight to my barrel. I had to chip off a small sliver of barrel, picture a circle divided into quarters, one of those quarters minus maybe 15-20% of it needed to be removed in a forward and upward direction to the holes on the sight. This was also the case with the 52 sight I accidentally installed first, the rear pin conundrum was what made me notice that like an idiot I installed a totally period incorrect sight on it....the lightening cuts should have cut my stupid fingers.
If I had a better set of calipers to measure the depth the pin placement would require on the barrel it would be another indication of a change at some point early on in pin placement alterations...for whatever reason. This and the PITA it was to fit an early 50 cover to it vs the 49 makes me lean towards mine being a late 49...possibly during an either/or transition regarding bayonets....and or other minor modifications we haven't discovered yet.
The grind marks on Jstn2's cover and receiver towards the bottom make me think a half assed attempt at fitting was done to a possibly out of spec, but likely just ill fitting by design 50 cover onto a 49 gun. Had I not known better (or been willing to do it right) I could have ground off the excess cover from behind rather than the pain in the neck front tang filing it required. Chances are once they got the tiny takedown pin hole lined up, they called it good. I think that must be the case with this Jstn2's 49/50...I really would like to see the measurments front of pin to front of sight for both of his...the actual 49 and the '50'
In hindsight the diagonal measurements seem a little likely to be inaccurate...measuring to the face of the FSB at least lends one flat surface.
I know nothing about cleaning rod nubs. Yet another fascinating new discovery here at SKS-Files
The amount of difference may be +/- a tenth of a millimeter or so, due to the tool used for the measuring....but the amount of difference between my original one and the fairly close to average differences on the other would be huge to the poor dumb bastard that has to pin those on straight. Ask me how I know....
Since these pin placements are not easily visibly discerned...I doubt the refurb guys would want to go to the trouble of keeping the parts together...since it doesn't seem much care was applied towards the exchangeable parts that came once the design was complete.
I am pretty sure this was by design, and another reason I don't think is very likely that stock ferrules would be changed to upgrade to the blade standard....between the top and bottom pinning, you would be setting the barrel up for failure, as a notch on both sides would be akin to how you cut down a large tree....yknow?
That being said, I probably have the only 49/50 that deserves to be tested for the presence of both pin notches....but I am also chicken.