Hello, I’ve been invited to show my soon to be project (inspired by MosinVirus on youtube channel)
I decided to dive in to my Zastava M83 and show some of the rough areas. This being my first revolver, my ambition is to turn it into a nice functioning piece. I’m hoping to get some good suggestions that I can practically incorporate.
Prior to me disassembling the revolver, the trigger pull was hard and felt gritty. Also, the primer strikes were off center, the cylinder stop has some slop in the frame (.008).
Certainly after exposing the innards it confirmed years of pollution was the blame.
After cleaning everything up and further inspection, I did notice that the trigger pin was a bit rough including the bearing surface inside the hammer.
The hammer does not appear to be IMI, appears cut from billet, I’m curious if its worth polishing the rough surfaces out of the hammer pin hole? How does one tell if the factory used case hardening or not, its hard to tell since its blued and the other color is hard to say what it is?
What is the acceptable hammer pin slop? I’m considering getting a set of pin gages (minus) and hopefully start my quest with dialing it in closer than Factory originally had and still maintain functionality
The trigger / hammer pin measure at ~0.157 in dia., holes in trigger / hammer measure at ~0.166. .009 seems big and its visually unappealing with the wobble.
Aftermarket parts are non existent, how does one go about creating a oversized two step pin as shown in the image (jewelers lathe)? Anyone have a different suggestion, sleeve the pin, can those be made in custom sizes?
Awesome to see you join the forum. There are quite a few people that came here from YouTube.
Since the pins/studs are easy to remove, you could have new pins made, but only after you ream the holes so they are smooth and you can take an accurate measurement of the diameters.
If the studs were pressed in, sleeving would be a good option.
If you want a good trigger pull there should not be slop. I would say at most the clearance should be .002
welcome
now remember something about cylinder slop - it is only a issue once the hammer is ready to fall (when the cylinder should be at 100% Locked up to maintain cylinder to bore alignment), Other wise it can be quite loosey goosey.
Thank you all for your nice welcoming words. I’m looking forward to the project.
Since it was recommended that the new pins be made, what type of material is typical for a hammer/trigger pin, something that can take cold bluing? Once I know the size of the pin dimensions as far as making them to size I’m open to suggestions.
For the cylinder play, I’ve seen the two points of contact the cylinder makes with side of the arm tip and the cylinder stop while the trigger is fully pulled and the hammer down. I have found that if I shim the bottom of the cylinder stop with a feeler gauge it makes the cylinder more inline with the barrel, I’ll pay whit that some more to see what comes of it.
Here is a visual on the play at the bottom (ca. .008)
I figure reducing that to .004 in the right direction shouldn’t be a problem?
Today I took some time to measure the parts, here is the sketch of the results with respect to cylinder rotation:
The view of the sketch with dimensions is capturing the view down the bore, as such shown in the next photo:
Here are some close ups of the cylinder stop, the bevel shown was there from factory:
For the arm, It seems that the cylinder is wanting to lead ahead by couple thou with the ratchet revolving each time (no contact between the arm/ratchet). The arm is right on the money thickness wise (trigger fully pulled) with meeting with the cylinder ratchet surface against the side of the arm tip. I have to rotate the cylinder back for the two surfaces to touch (ratchet surface against the side of arm). Only then does it seems the barrel is in-line with each chamber.
I took some photos of the casings, I’m convinced the cylinder is leading due to the .008 frame slop of the cylinder stop:
Here is the tip of the arm, you can see the scuffed surface near the top left side (just below the tip):
And here is the cylinder ratchet showing the part of the ratchet surface that supposed to make contact with the side of the arm with the trigger fully pulled:
I’m thinking shimming the cylinder stop might do the trick, would bringing the .008 clearance down to .002 be a problem from a mechanical movement stand point?
I have never timed a revolver to tell you the truth, but i know that when the trigger is in SA position, the cylinger should not have any rotation slop.
I am not sure about shimming a cylinder lock. Looks like a simple enough part to make new, thicker to prevent play while restoring the needed geometry.
From looking a the trigger / hammer pins, it appears that the trigger pin with the cover plate assembled was sitting firm in frame compared to the hammer pin:
From the photo you can see that the trigger pin (top) is less marred on the ends that sit inside the frame, where as the hammer pin was loose and is rotating inside the frame along with rotating with the hammer itself, notice the marred surfaces all over the pin:
Should the pins be allowed to spin freely inside the frame with the cover plate assembled? My intuition tells me that the pins should be fixed while the hammer / trigger revolve around the fixed pins.
If you notice the slight curvature on the pins where the thinner transitions to thicker part of the pin, that profile was probably intended to get fixed in the frame?
I have no experience with these revolvers, but the curved transition on the pin is there for strength most likely. The openings in the frame and side plate are likely countersunk slightly to account for the radius of that transition.
If the pins are not pressed in it is okay for them to turn, but the less slop you have the more consistent the action will be.
Mosin, I dig the beard, looking forward to the bigger shop, I too need a large work space besides my computer desk
Yesterday after almost 2 weeks I got the package in the mail:
Turns out I was way way off on my hole diameter estimates…
The hole measures at .159" dia minus and the .160 pin does not want to get in, that really embarrasses the set of calipers I used with the .166 previous measurement using the inside jaws.
The stock trigger hammer pins measure .157" dia, which brings the as is condition to within .002".
Feeling a bit dissatisfied with the result I inserted the .157" pin from the gage set just to see what it feels like, and sure enough .002 of looseness does feel like a 1/16" of play at the end of the hammer and trigger.
The frame holes are within .001".
Now I wonder how tight of a revolver should I go for?
So it isn’t as bad as we thought, which is good.
How tight? I would say .001 clearance will not hurt taking it apart or putting it back together. Make sure to ream the holes smooth first though
Now it will be chasing the reamer size, I’m thinking 0.160 reamer would be a good finish size taking out the rough inside of the bearing surface, then machining the pin to 0.159 size would be perfect fit.
Mosin, do you know what I could do to measure the inside bearing surfaces of hammer and trigger positions?
With the hammer & trigger pins removed the side cover plate seems to be sitting more flush against the revolver frame. Something that I can insert from top of the frame for the hammer and from the bottom of frame for the trigger that can measure to .001 reliably?
Feeler gauges would work in addition to known width bar.
But since you mentioned that with pins the side plate sits high and without them flush, I would measure pins, width of hammer and trigger, etc. Then compare to the space allowed between the frame and side plate.
If your frame and side plate don’t have bearing surfaces at pivot pins, and neither trigger nor hammer have them too, you could use shims at those.
I was thinking the same thing with using feeler gauges, but I was thinking the room of error with stacking them up with percent of error magnifying with each. I like the idea of using a known bar size and then perhaps adding a single feeler as shim, thanks.
This is something that I tried to convey early on with the pin holes inside the frame having a raised edges. Here I try capturing that, it is rough to the touch and catches on nail:
Any ideas with removing the raised edges, large drill bit to deburr (chamfer the high spots)?
Same with trigger & hammer pins, here is a closeup of the ends, you can see where the bite is at diameter transition:
It appears as if the frame is biting into the pins or vice versa… It could be that both are made of same material.
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