Mosin rough bolt

[gbeecher]

I've owned a Mosin 1891/30 for 3 years now, and it's been a great rifle. I've shot 300+ rounds thru it, firing Brown Bear and Silver Bear 203 grain soft point with no problems, other than tightening the sear spring screw a few weeks ago. Last week at the range, I was shooting some Russian no-name, new 148 grain fmj, and noticed the bolt cycling was rougher than usual. Anyone else notice a difference shooting the Mosin with different case materials? I cleaned it good the other day, with scrubbing the bore, chamber, receiver and bolt face. I've got a mix of Brown Bear and the fmj no-name ammo left, and will try it at the range again soon.

 

[WardenWolf]

Which part of the cycling was rougher than usual? If your Mosin's stock has shrunk, the magazine well can protrude into the path of the bolt and make it rough if you tighten the rear action screw down enough. That's a problem I've personally encountered. The fix there is to either shim it or file it down.

 

[gbeecher]

Not really 'rough', just not as smooth as usual. I noticed it on the last quarter inch turn to lock the bolt into battery and the last quarter inch on the bolt upswing to completely un-lock the bolt. I thought it might be a dirty bolt face/extractor. This was the first time I cleaned that part of it in 300+ rounds fired.

 

[BCRider]

I've seen a lot of references to the varnish used to protect the steel casings on the milsurp ammo causing a build up of crud in the chamber. That and the frequently noticable deformation of the shoulder or even splitting the milsurp spent casings implies that they are not the best shape.

I've yet to get all the goodies together to let me reload my own ammo for the Mosin. But your results with good stuff vs milsurp sure make me want to get more serious on it. That and the typically 8 to 10 inch groups at 100 yards that I get with the milsurp stuff. Granted my eyes aren't the best with plain irons but I manage to get 4'ish inch groups with my other plain iron rifles just fine. It would be nice to see the Mosin get down to that size as well.

 

[ball3006]

Shooting that steel cased lacquer coated ammo will cause that.....chris3

 

[WardenWolf]

No, no, no. Lacquered ammo does NOT cause that. It's an old, old myth. What it's actually caused by is simply steel-cased ammo, lacquered or not. The problem is that steel cases do not expand as much as brass does, resulting in a poorer gas seal. Gas and carbon fouling will blow by the case into the chamber until there is enough buildup to result in a good seal. Of course, a tighter chamber fit will also result in a little more effort being required to work the bolt.

Word of warning: do NOT shoot brass-cased ammo after shooting steel without cleaning it first. Brass expands more than steel, and that extra expansion on an already-fouled chamber will result in it getting stuck like glue. You'll be needing a mallet to get the bolt open if you do that.

 

[gbeecher]

Prior to this week, I had not cleaned the chamber, extractor groove, bolt face or extractor in over 300+ rounds fired. On Monday, I gave the rifle an extra good scrubbing and cleaning, including the areas I mentioned. I took it out of the closet today to inspect it under bright light and a flashlight. The extractor groove and bolt face recesses still looked dirty, so I cleaned them up some more. I'm hoping to go to the range next week, so I'll see if any of it helped.

 

[schnarrgj]

With my Mosins, more than a few, I have noticed at times that certain ammo is harder to close and open the bolt also. I found out that sometimes the rim is a little thick on some runs of surplus ammo, In that I have not shot them for a while, I do not remember which years and who made them. Cleaning the bolt face, chamber and extractor, can only help. I normally do that with every cleaning because all the surplus ammo I have is corrosive. That lacquer builds up in the chamber has been shown to be false. Hope this helps.

 

[caribou]

WardenWolf said it perfectly

"Sticky Bolt" is the name of the game and its a Mosin's way of saying "Clean Me!"
Clean the blot till it shines, its bare steel, so oil it some too.
For the chamber and bore I use the right sized brushes, and with corrosive ammo I use boiling hot water, often with soap, a good scrub, a boiling hot rinse and the heated water and steel dry themselfs, then a patch or two with or without solvent till clean , then an oiled patch and its done.

 

[maxyedor]

It may simply have been dirty, but to me, it sounds more like an ammo issue, if I read your posts correctly. If it closed like butter with Brown and Silver Bear, but this new ammo is rough in that last 1/4 turn, it's likely one of the dimensions on the case causing issues.

If that's the case, it's easy to figure out with brass ammo, a little harder with steel. Take a clean round, if they're a little grungy you can tumble them, and chamber it. Now clear the chamber. Take a look at the round and check for witness marks. You'll probably see light rubbing somewhere on the base of the cartridge. You can also spray it with Dye-Kem, or scribble all over it with a Sharpie to further enhance the witness marks. Generally the shoulder isn't pushed back far enough, may be a headspace issue, may be a brass issue, only headspace gauges and case gauges will tell you. However, being a rimmed cartridge, it may be a rim thickness issue, check that with a caliper.

Most of my guns have one brand or another ammo that takes a little extra nudge to close the bolt on, some very minor, or in the case of my Remington 700 target gun, you'd need a hammer to close the bolt on Remington ammo, everything else is fine.

 

[tyeo098]

Rim thickness IS the headspace on x54R

Rimmed cartridges headspace off the rim.

 

[stubbicatt]

Rim thickness IS the headspace on x54R

+1

I suspect you will find that if you clean it well, it will operate properly. I don't know if you do this or not, but a little grease on the bolt lugs sometimes helps.

 

[Matt Dillon]

When I shoot Czech silver tip I have to use a dead low hammer to open the bolt. I have scrubbed the bore incessantly to no avail. I have no issues whatsoever when I shoot my reloads.