Friday, March 26, 2010

Mosin upgrades

Due to my poor performance on the Mosin Nagant, instead of working on holding it more steady, my breathing, or my trigger work I decided to 'improve' it. You won't really be able to tell the difference from the outside, but inside stuff is changed.

First thing I did was polish all mating surfaces in the trigger group. There were huge (small) gouges (scratches) that made it feel rough, or so I was told. Went to 1500 grit sandpaper in the end.
The inside of trigger:

The sear, where it catches the cocking knob:

The sear, where it rubs on the inside of the trigger:

The cocking knob, where its held by the sear:

I also added some shims to where the trigger spring/sear attaches to the receiver. This reduces the trigger pull, but can be dangerous if you do it too much. I did not do it too much. I did not test the trigger before the mods, but post polishing, the trigger pull was about 5lbs (which is a bit low for a stock mosin, maybe I accidentally bent the trigger spring while polishing?). After shimming the trigger spring, it went down to 3.9 lbs. I tested the trigger pull in a (mostly) inaccurate way. I used a gallon milk jug and added or removed water until the trigger just barely tripped when I used a rope to hold up the jug using the trigger. I measured the number of cups of water in the jug and converted that into a weight.

Second, I hoped to make the barrel more consistent. I cut some (three) squares from a coke can to put under the front of the receiver (where its screwed in). This raises the receiver and barrel a bit from the stock. (the Finns used brass) Then I sanded the stock where ever the barrel was touching, so that it was free floating. I had heard on the internets that the mosin barrel is a bit thin, and warps with the increase in temperature, so free floating completely is not a good idea. I put some cereal box cardboard under the barrel at the front of the stock. This puts pressure on a known location of the barrel, often people use cork, and its called "corking". So, the barrel was free floated from the chamber to the front of the stock. Then, the handguard was putting pressure on the barrel (the top of it), so I added some cardboard shims to the bottom of the handguard so that the barrel was floating within the handguard/stock except the front of the stock where I wanted the pressure to be.

I also did some cosmetic work on the sling. I also had some problems with my original idea to hold the sling. The "button" (which wasn't really a button but sort of worked like one) slipped out once while I was out in the woods, and I had to eat a pb&j so I could use the ziplock part as a piece of strong rope. Anyway, I made some "dog collars" to hold the sling on, using some old boot leather and an old coat hanger (with some dental floss as thread).
As you can tell the one on the left was made second. They fit perfectly.

1 comment:

Spatchcock said...

I can vouch the modifications make the trigger more agreeable. After taking up slack, there is very little motion until the sear breaks. This is universally agreed upon to be desirable.

The only remaining problem that I can see is the lack of trigger return spring means the bolt isn't captive in its raceway. You could put your eye out when cycling! I trust Uniquely Joe will fix that in due time.

Otherwise, the Mosin Mods appear to address my complaints. I look forward to firing it!