New Bolt Head

[Kristie]

Okay. Makes me think I should have gotten the go-gauge, too. Wonder what it would tell me?

[WeldonHunter]

Okay. Makes me think I should have gotten the go-gauge, too. Wonder what it would tell me?

The go gauge is not one that is generally used. Most problems are from to much headspace and the go gauge is for checking minimum headspace. It's mostly for setting up a new barrel which is not something anyone does with a Mosin Nagant. I would exhaust all other avenues before thinking the problem stems from to little headspace though what you're describing sounds like that could be a possibility. Try seeing if a round sits in the chamber with no bolt. If it looks right maybe try removing the extractor and see if you can chamber a round and close the bolt as suggested before. I will stress again. If you doing this with live ammo make sure you follow all safety procedures. It's easy to get frustrated and forget safety. Treat the firearm like you're at the range. Dummy rounds are best for this type of thing.

[Junk Yard Dog]

The problem is not extraction, the rifle has failed to pass headspace using the No/Go headspace gauge twice. He has swapped the bolt head and the rifles is still a fail.

Wait, it's not supposed to close on the no-go, so it's passed with both bolt heads, right?

EDIT: Weldon, you beat me to it, and I'm glad you brought up the old thread for me, which I needed after all. Yes, the problem is getting the bolt to close on most rounds, not all. Sorry for all the confusion. I feel like I'm being an immense problem, here. I wish the problem would go away, so I can, too!

Never mind me, I am confused and wasting my time, and yours, situation normal, I can't see small print for shit anymore, I thought it said it didn't pass. Good that it did as I have been assuring people for years that a bolt head swap fixed headspace in these.

[WeldonHunter]

The problem is not extraction, the rifle has failed to pass headspace using the No/Go headspace gauge twice. He has swapped the bolt head and the rifles is still a fail.

Wait, it's not supposed to close on the no-go, so it's passed with both bolt heads, right?

EDIT: Weldon, you beat me to it, and I'm glad you brought up the old thread for me, which I needed after all. Yes, the problem is getting the bolt to close on most rounds, not all. Sorry for all the confusion. I feel like I'm being an immense problem, here. I wish the problem would go away, so I can, too!

Never mind me, I am confused and wasting my time, and yours, situation normal, I can't see small print for shit anymore, I thought it said it didn't pass. Good that it did as I have been assuring people for years that a bolt head swap fixed headspace in these.

Don't feel bad Jim I'm the same way. I can remember the weirdest crap and forget the easiest to remember. I had some people come by today to buy 6 of my turkey's. I shook his hand as he introduced himself and told me his name and 5 minutes later I couldn't remember what he told me it was to save my ass. Still don't.

[Junk Yard Dog]

That is why I love the security cameras at the shop and home, I always forget names and numbers, I just pull the footage out of the DVR, like a $6000 post it note.

[bunkysdad]

Everytime we get one of these threads where this is happening, and the extractor has been removed and cleaned underneath, and does extract properly by clipping onto the rim of the cartridge, it seems that after pulling out a lot of hair it turns out to be a burr in the chamber area. Think about it. It doesn't take much. You might not can see it. But I bet it is there. You are passing no-go headspace. Sometimes the bolt closes when you are shooting. A dental pick, going around every area of the chamber may just find something. The same way the dentist finds crap on your teeth, even though you flossed and brushed for a solid hour before your checkup. Keep it simple, walk away if you get frustrated. After shooting police your brass so you can inspect them under a lense if need be.

[Kristie]

Everytime we get one of these threads where this is happening, and the extractor has been removed and cleaned underneath, and does extract properly by clipping onto the rim of the cartridge, it seems that after pulling out a lot of hair it turns out to be a burr in the chamber area. Think about it. It doesn't take much. You might not can see it. But I bet it is there. You are passing no-go headspace. Sometimes the bolt closes when you are shooting. A dental pick, going around every area of the chamber may just find something. The same way the dentist finds crap on your teeth, even though you flossed and brushed for a solid hour before your checkup. Keep it simple, walk away if you get frustrated. After shooting police your brass so you can inspect them under a lense if need be.

It extracts fine, but I can kind of see some metal shavings in there I'd like to get out. Problem is I don't have a dental pick, and was just thinking I need to get something like that. The other thread shows some pics of cartridges with bits of metal scraped off, but it's hard to see.

Last night I tried inserting a cartridge by hand and found it goes in very smooth. The rim sits down all the way in there just fine, too.

[entropy]

Any possibility of a case separation? That certainly would cause the bolt to not close with two diferent bolt heads, and wouldn't be an obvious thing. Have you looked into the chamber itself and checked for this? I would assume you'd have noticed if you'd fired a round and exctracted only the rear of the case, but weirder things have happened. If you have a separated case, it's not that hard to remedy. A broken case extractor isn't expensive, but it is an operation that calls for care in doing.

[Kristie]

Any possibility of a case separation? That certainly would cause the bolt to not close with two diferent bolt heads, and wouldn't be an obvious thing. Have you looked into the chamber itself and checked for this? I would assume you'd have noticed if you'd fired a round and exctracted only the rear of the case, but weirder things have happened. If you have a separated case, it's not that hard to remedy. A broken case extractor isn't expensive, but it is an operation that calls for care in doing.

No separated cases. Haven't heard of that problem yet!

[Kristie]

Okay, guys, here’s my progress. I removed the extractor and tried operating the bolt with and without a round, and found that it still operates the same no matter what. So it’s not an extractor issue, or a burr. Just for the heck of it, though, I got in there with a bent paperclip and q-tips and cleaned out a bunch of shavings from rounds and other gunk that had built up. There wasn’t a lot, and I didn’t find anything lodged in there, but at least it’s that much cleaner.

So I tinkered around some more and started looking really closely at the bolt and how it operates in the receiver. And I think that after looking at how much it’s wearing where the bolt comes into contact with the front of the receiver and the back of the receiver in the various stages of cycling it, I think the problem is it’s fitting in there too tightly. The bluing has worn off in spots on the receiver, and on the bolt the metal is very shiny. At the point where the bolt becomes tight to try and close, there’s space between it and the receiver at the front, but not at the back. I think it’s griding together so tightly, that that’s why it’s hard to close. Without a round, it’s not very tight, and with one, it’s horrible. I think the back of the case pushes the bolt back so far, that’s what’s causing it to grind so much. And even when I do get it closed on a round, there's still a little gap in front and no gap in back.

Now, I did notice that the backs of some of the cases are rubbed shiny in spots, too. So…I’m a little stumped on that part. Maybe it’s even normal.

Front of receiver:

Back of receiver (image is upside down):

Back part of bolt where it contacts the receiver:

Point where it begins to bind (space in front, no space in back):

Side view on bolt/receiver contact in back:


So it looks like I've got some sandpaper work, and maybe that will take care of it.

[Kristie]

I didn't end up finishing the sanding yesterday. Got sort of burned out on it and said enough was enough. So as far as I got was to bring back that surface enough so that it's contacting in the middle now instead of the edge. I had started with 1200 grit, which wasn't effective enough at removing metal, so I moved up to 800 and then 600. Seems like it's still going to take a lot ofelbow grease, though. I also gave it a rest because I was hoping for some feedback on whether or not I was doing the right thing. Altering the bolt, however little, makes me a little nervous, so I was hoping to hear that someone concurred
that this is the problem. I could be way off and not even know it! So give me a shoutout with any thoughts!

[Luthierseye]

If it closes on the go-gauge and not on the no-go & field and chambers and closes on some rounds and not others then I suspect the ammo(esp since there was chaffing in the ammo pics on the original thread). Maybe the easiest test would be to get a box of recently produced brass cased ammo and test fire it.

[Luthierseye]

Unless I'm missing something from a previous post....

[Kristie]

I only have a no-go gauge, and it passes. I've used surplus from a spam can, Russian non-corrosive ammo from a box, and some loads a buddy gave me. I think they've all been problematic, the handloads the least, if I remember. They must've been brass.

[Longcolt44]

Try this. Take a black magic marker and color all the places on the bolt that you think are rubbing. If it is in fact the bolt or parts on the bolt it will show by it rubbing off the marker. If it is not the bolt do the same with the chamber area. The marker will come off any parts you color after you see the problem with some lacquer thinner.

[entropy]

Inspect your chamber very, very thoroughly. If you have another Mosin that shoots fine, inspect that one and compare. It sure sounds like a chamber issue. Most Mosin bolts are so loose in the reciever that you can move the bolt up and down quite a ways while closing it. If it happened with every round, too strong of a trigger spring (of which the tip is the sear) could be suspect, but since it is intermittent, the most likely causes are: 1) Sticky Bolt syndrome, 2) a burr or burrs in the chamber, 3) out of spec ammo, 4) a spearated case, or 5) an out of spec (too tight of a) chamber. THis is going from most likely to least. (Also, easiest to fix to hardest, except the ammo.) HTH.

[Kristie]

Well, it's been over a month of trial and error, but I think I've finally discovered it's the ammo. Because sanding the bolt didn't work, a new bolt head didn't work, an entire new bolt didn't work, and cleaning out the chamber with a brush chucked in the drill didn't work. So I got a box of PPU and it works FINE. But now I don't know what to do. There's no way I want to keep paying 3 times more for "good" ammo, or I'm not even going to want to be shooting the gun! If the surplus ammo is "out of spec", what do you think the chances are of me getting another 440 round batch like that, and doubling my aggravation? The only reason I got this gun in the first place was because I thought I could shoot it for cheap. Also, the surplus stuff isn't all I've tried in it. I also tried handloaded brass cased cartridges, and then some Russian "hunting cartridges" which I would have thought were at least a little better quality. So three out of the four I've tried were hit or miss as far as being able to chamber without any issues. If finding ammo that works for it is going to be such a problem....I don't know, but it's just going to suck! If this stuff is out of spec, it's probably that the rim is too thick, right? Nothing you can do about that. And I'm guessing there's nothing that can be done to the gun to make it more tolerant, either. I'm disappointed in the whole thing.

[rjmt]

what does it take to match a relacement bolt to a reciever? I have one that's worn out
the bolt handle starts to raise out of position when you pull the trigger?!?!

rjmt

[Kristie]

what does it take to match a relacement bolt to a reciever? I have one that's worn out
the bolt handle starts to raise out of position when you pull the trigger?!?!

rjmt

As far as I know, it shouldn't be a big deal. They're all supposed to be basically interchangeable.

[gbeecher65]

Sorry to hear of your problem. A Mosin should be fun and cheap to shoot. The low price is certainly what attracted me. I've shot Brown Bear lacquer coated steel case; Silver Bear zinc coated steel case and Novosibirsk copper washed steel case. The Brown Bear cycles easily, Silver Bear is 2nd and the Novosibirsk can be a little stiff to cycle. I've settled on the Novosibirsk, because it's the cheapest. I can only guess, but your problem is either a burr and/or deformed chamber. Unfortunately, you might have just gotten a 'bad' Mosin. I always thought that the Russian Mosin tolerances were so loose, that most problems were minor ones. Best of luck to you!