Mosin trigger/sear work questions?

[AlexI]

Picked up my new M91/59 last night, took it apart and cleaned/oiled everything (surprisingly, almost no cosmolene on it, except some inside the bolt).
The trigger actually feels pretty good (not a hair trigger, but quite smooth though long single stage pull).
However, I noticed that the very edge of the sear is definitely burred over. I mean the very edge that catches/releases the cocking piece, on the part that I think is a combined sear/sear spring. Does my description make sense?
Anyway, I would think a noticeable burr in that place can't be good for the trigger pull, and removing it can do nothing but good. The sear/sear spring part looks to be very easy to take off/reinstall (just one screw holding it in place). I plan to stone the contact surface just enough to remove the burr, and polish it a little, no more than that. Does it sound like a good plan, or there is more to it then meets the eye?

Also, I was surprised by how the trigger is freely flopping back and forth when the bolt is cocked. But this looks to be a design feature rather then a problem. I looked at the trigger mechanism and there is no provision for anything like a trigger return spring to hold it in position. Is it true or am I missing something?


BTW, if moderators think this post belongs in the Gunsmithing forum, please feel free to move it.


Thank you.
Alex.

 

[Cosmoline]

Without seeing the bur it's difficult to say. If it's just a small piece of steel sticking out that could be filed down flat, that would be fine. If it's more like pitting on the sear that's a bit more disturbing and I'd be worried about taking too much steel off.

The trigger is designed to be floppy.

 

[yesterdaysyouth]

one easy way to shorten the length of your trigger pull is to reduce the travel.... to do that just shim out under the screw that holds the whole thing to the receiver, if you do it right you can really help it out...

 

[AlexI]

Thanks for the replies!

The burr is really some steel "sticking up" along the contact edge of the sear.. kind of like you sometimes see on a badly sharpened knife edge, only bigger. Looks like it is really asking to be removed.

I am considering shimming the sear too, but it probably wouldn't be necessary. The trigger pull is not bad as it is, and removing the burr/polishing will make it more then good enough (and hopefully safe).

Alex.

 

[student]

My M44 had a typical long spongy trigger pull. I polished the place where it contacts the bolt and holds it back, then I ground/polished the sear that holds the bolt back so that the overlap was less prominent, in short, a shorter trigger pull that is smoother and lighter (the original would noticibly move the bolt around if I did it slowly).

 

[AlexI]

I did my trigger work last night. Polishing the sear and trigger surfaces didn't produce any noticeable improvement in trigger pull length or weight, just made it a little smoother.
Apparently, that sear could take quite a lot of grinding without getting into trigger safety problems... But I decided to take a reversible approach for now, and shimmed the sear with a "washer" cut out from 4 layers of masking tape. That did reduce the trigger pull. I measured it roughly (hanging objects of known weight on the trigger with a piece of string) and found that it is at 4-5 lbs now. I found it acceptable for now, but there is room for improvement in the future, since this trigger is really easy to work on!

What do you think is a reasonably safe trigger pull weight to attempt on a Mosin trigger, anyway?

Alex.

 

[longrifleman]

check this out:

I haven't tried this yet. I picked up the taps but haven't got any farther. I have an M44 with about as bad a trigger as I have ever pulled, so it is a perfect candidate to experiement on.

 

[AlexI]

I liked the idea with the set screw to adjust trigger pull (a link from the page you posted) better. A simpler and more elegant modification, and can be fine tuned with the whole rifle assembled, just take the bolt out and you can reach it with a wrench!
Sure it does not address overtravel, but what is so very bad about overtravel? It happens after the shot is fired, and doesn't hurt anything so far as I can see... I honestly have no clue why people try so hard to eliminate overtravel, so I would appreciate it if you explained it to me?

Alex.

 

[longrifleman]

Sure it does not address overtravel, but what is so very bad about overtravel? It happens after the shot is fired, and doesn't hurt anything so far as I can see...

I'm probably not the best person to address this (any competition shooters around?) but I will give my opinion. Of all the problems with triggers, overtravel gives me the least trouble, so I wouldn't argue it is a major problem. I think the problem seems to be aggravated by a heavy trigger pull before the overtravel. For me, this increases my tendency to jerk the trigger. Any movement of my body after the shot goes off adds a variable to the hold that generally decreases my accuracy. How much seems to vary from gun to gun.

If it doesn't bother you then your life will be much simpler. Me, I need all the help I can get.

I have more trouble with "mushy" triggers without a defined let-off, especially on long shots. I can't predict the shot so keeping the sights centered through normal movement gives me fits. That is why I like sandbags so much.

I liked the idea with the set screw to adjust trigger pull (a link from the page you posted) better. A simpler and more elegant modification, and can be fine tuned with the whole rifle assembled, just take the bolt out and you can reach it with a wrench!

One reason I haven't done my trigger is that modification. I can't decide which one to do. So I haven't done either.

If someone out there in internet land has tried both help me decide.

 

[AlexI]

OK, now it makes some sense. Overtravel can cause you to jerk the trigger after the break, but before the bullet has left the barrel. Probably a minor variable, but I understand why at least competition shooters would want to avoid it.

Well, I am not a gunsmith, but here is what I would do (and may still do later):
- first, add that set screw to adjust the trigger pull;
- then, take care of the overtravel in a very simple and direct way: just drill and tap the trigger guard directly behind the trigger, and put another set screw through it, of whatever length will be necessary to stop the trigger right after it breaks.
The only downside will be that the trigger stop screw will be visible... But, both trigger pull and overtravel will be easy to adjust, and you will not have to do anything more complicated then drilling and tapping.

How does this plan sound?

Alex.

 

[longrifleman]

How does this plan sound?

Sounds good. There are several firearms around that use that system to adjust for overtravel. Some mount the setscrew in the trigger itself, instead of in the guard. If maintaining the originality of the rifle is important, you could get a replacement trigger and modify it instead of the rifle.

Personally, I don't consider most M/Ns to be sacred so modifying one doesn't bother me. Hiding the modification in the stock is a reasonable compromise.

What do you think is a reasonably safe trigger pull weight to attempt on a Mosin trigger, anyway?

Your 4-5# is what most folks consider adequate for hunting rifles. If all your shooting is at targets you could lighten that up. Go ask the guys on the competition forum what some of them use! Given the looser tolerances that M/Ns were made to, I wouldn't feel comfortable with much less than what you have. Too much chance of things flopping around if it's whacked hard enough. Your rifle, your choice.

If you haven't already, check out the safety modification on that website. If you try to put on the M/N safety in cold weather, with or without gloves, you will appreciate the idea. I think he borrowed the idea from the Swiss K-31. If your gonna steal an idea, steal from the best.