M91/30 sight issue

Buck Turgidson

Buck Turgidson

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As we all know, M91/30's shoot aprox 8-10" high at100yards. there are 2 ways to fix this problem that i know of.
1. Raise the front sight.
2. Lower the Rear sight

since the rear sight is at the max 100m. the only option would be to shave material off the base of the sight (not doing that)

the other option is to raise the front sight (what i want to do)

now, my dad is determined that the best way to fix this high POI problem is to adjust the bedding (shim the rear) to bring the POI down?

Is this the correct solution?
 
Drift off the front sight and post assembly. Place the sight upside down in a padded vice. From the bottom dove tail, locate where the pin was inserted. Using the same size bit as the front post, drill out the post.

Using a piece of metal rod the same thickness as the original, insert the new longer front post. Use epoxy or solder it. Cold blue the visible rod. Replace the front sight onto it's base.

Attend the range with a suitable sized flat file. With the ammunition you intend on always using, zero at 100 m. File the post down slowly, confirm zero for poa-poi.

If you switch from heavy, light or commercial ball ammunition, your poi will shift.

Voila! A Mosin Nagant that doesn't group a foot above point of aim....
 
rchmontreal said:
Drift off the front sight and post assembly. Place the sight upside down in a padded vice. From the bottom dove tail, locate where the pin was inserted. Using the same size bit as the front post, drill out the post.

Using a piece of metal rod the same thickness as the original, insert the new longer front post. Use epoxy or solder it. Cold blue the visible rod. Replace the front sight onto it's base.

Attend the range with a suitable sized flat file. With the ammunition you intend on always using, zero at 100 m. File the post down slowly, confirm zero for poa-poi.

If you switch from heavy, light or commercial ball ammunition, your poi will shift.

Voila! A Mosin Nagant that doesn't group a foot above point of aim....
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Thats one good bingo, worked for me. My only mistake was that i used the no 40 drill bit that i drilled it out with as the new front post. Let me tall you how much fun i had with my dremmel knocking that thing down 2 mm. Should have used something softer.

Also the stock post is supposed to be 15.5mm from the barrel to the tip of the post. I made mine 19.5mm which was too tall, now down to 17mm and have to get to the range to try it out.
 
so the shimming idea is NOT the correct way to lower the POI? my dad seems to think that raising the front sight is putting a band aid on a bedding problem.
 
Elevation is adjusted using the rear sight. If the point of impact (POI) is too low, raise the rear sight. If it is too high, lower the rear sight. If the rear sight is at the lowest setting, you will need a taller front sight. Windage is adjusted by drifting the front sight with a brass punch. Later Finnish models (M28/30 and M39) have adjustment screws on the front sight. Loosen the screw on the side which you want to move the sight towards and then tighten the screw on the opposite side the same amount. Move the front sight to the left to move the POI to the right and move it to the right to move the POI to the left.
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Now for the other question that poped up.
It depends on the model. I'm not aware of a source for taller early blade type sights. The post on some of the later globe type sights can be replaced from the bottom, after removing them from the barrel, with a finishing nail and then filed to length. Otherwise a quick non-permanent fix is to slip a small piece of tubing (wire insulation, coffee stir stick, roll pin, etc.) over the post and trim it to length. Taller blades for the later Finnish models (M27, M28, M28/30, and M39) are available from time to time.
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Take a Q-Tip (the kind with a coloured hollow plastic tube) and cut off an amount about 1/4" longer than the present front site post. Slip it over the metal post and cut off small increments until your gun shoots where you want it.
 
Buck Turgidson said:
As we all know, M91/30's shoot aprox 8-10" high at100yards. there are 2 ways to fix this problem that i know of.
1. Raise the front sight.
2. Lower the Rear sight

since the rear sight is at the max 100m. the only option would be to shave material off the base of the sight (not doing that)

the other option is to raise the front sight (what i want to do)

now, my dad is determined that the best way to fix this high POI problem is to adjust the bedding (shim the rear) to bring the POI down?

Is this the correct solution?
Click to expand...

Comrade? Are you shooting with your bayonet attached like a good communist? These rifles were sighted in with the bayonet mounted, and you must keep it attached at all times, or the fascists will kill you.
 
Buck Turgidson said:
has anybody even heard of shimming or bedding mods to correct POI? like i said, my dad seems to think its the ONLY way
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Raising the front sight IMO is the way to go. I can see bedding or shimming making it more accurate but think about it, if you bed the action does the rear sight move on it's own and the front sight not move?

Nope. They will both move and still be in the same spot in relation to each other. I raised my front sight (too much) but it had the effect i was after.

My guess is your dad has scopes on all his rifles and they are hunting rifles.

Good luck
 
skirsons said:
Comrade? Are you shooting with your bayonet attached like a good communist? These rifles were sighted in with the bayonet mounted, and you must keep it attached at all times, or the fascists will kill you.
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I plan on hunting with this rifle. if i have to carry the bayonet around, I will snag it on every branch in a 5 ft radius. I can handle fascists, but the bears will get me
 
I guess I'm lucky.

Mine is low so I just raised the elevation with the slider thingy.

Problem is the thing sometimes got stuck or bumped in the bush and slid up or down without me knowing. I shot over a bear one time and under another time.
 
Buck Turgidson said:
has anybody even heard of shimming or bedding mods to correct POI? like i said, my dad seems to think its the ONLY way
Click to expand...

I hate to disagree with someone's Dad, but no. Bedding can correct a "wandering zero", but POI is mainly a function of the relative positions of the front and rear sights. With scoped rifles we adjust the scope to change the POI, we don't change the bedding, and so it goes with iron sights.

Military guns are often designed to shoot quite high at 100 yds and most civilian shooters want them to shoot lower. When it shoots too low with iron sights, typically a higher front sight is installed, if too low, the rear sight can be raised.
 
Andy is dead on. Bedding just means the action is more stable. It will only allow the gun to more consistantly shoot wherever it's already shooting. I suppose if you put enough pressure through bedding to bend the barrel, it would work, however I think that's completely defying the purpose.

The qtip/ sight sleeve idea is my preference. It's really easy, fast, can be glued in place, can be removed, and if you get it wrong, it's easy to redo. That and being plastic inside a sight globe it'll stand up to abuse.
 
tokguy said:
I shimmed mine. There is a how-to on www.surplusrifle.com. Pretty good stuff on M/N 91/30's. I floated the barrel, shimmed it & worked over the trigger with info from this site.
It's probably worth a look if you like amatuer gunsmithing.
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so you shimmed it to correct a high POI?? I wouldn't say I like amateur gunsmithing. I like budget gunsmithing, but I never want to do anything unless i'm 100% sure i wont make permanent changes/damage. that's why i like the blue Q-tip idea. cheap. no permanent change

I agree with the no bedding fix. it seems to me if you raise the barrel at the receiver to bring the muzzle down. the muzzle comes back up when you re-alligne the front and rear sight as per normal shooting.
 
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