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  1. #1
    Join Date
    Oct 2012
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    5

    Default Mosin PU Head Space Problem - How to adjust?

    I just got my Classic Arms PU a week ago - have not brought it to the range yet.

    In my cleaning and pre-checks I was trying to cycle a spent case and the bolt was hard to close - then failed to extract. I had to use the cleaning rod - an extention - and a hammer to get it out (Was not happy). At first I thought it was the bolt/extractor... so I tried a bolt out of my seasoned mosin - same result.

    So I thought - could be the round - I then tried cycling the round through my seasoned mosin and it worked - I used both bolts (PU and my seasoned mosin)

    My conclusion is that it is the headspace that is just too much to hook the round to the extractor.

    I have seen multiple posts about the what causes the extraction issues - and headspace is usually listed - but I have not found any the tell how to adjust it.

    HELP ME PLEASE - I don't want my new Classic Arms PU to be a wall hanger!!!!

  2. #2
    Join Date
    Mar 2012
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    Default

    I wouldn't worry too much if a spent case won't cycle. It's pretty normal for a fired case not to be chamberable until it's been sized. Your other Mosin may just have a looser chamber than the pu.




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  3. #3
    Join Date
    Aug 2010
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    NM
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    I had a very bad experience with a spent case from a standard Mosin being chambered in a Finn M39. I did not get it out. The casing was destroyed in the process and is still in the M39.

    Never chamber a spent casing. Its okay in the rifle it was fired in, but if you close the bolt on it in a tighter chamber you are jamming it in there but good.

  4. #4
    Join Date
    Dec 1969
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    North Dakota
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    Quote Originally Posted by Ol' Relic View Post
    I wouldn't worry too much if a spent case won't cycle. It's pretty normal for a fired case not to be chamberable until it's been sized. Your other Mosin may just have a looser chamber than the pu.
    +1

  5. #5
    Join Date
    Jun 2011
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    1,069

    Default

    Quote Originally Posted by turbodan View Post
    I had a very bad experience with a spent case from a standard Mosin being chambered in a Finn M39. I did not get it out. The casing was destroyed in the process and is still in the M39.

    Never chamber a spent casing. Its okay in the rifle it was fired in, but if you close the bolt on it in a tighter chamber you are jamming it in there but good.
    You should be able to take to a local gunsmith and he SHOULD be able to remove it. Would be worth a try.

  6. #6
    Join Date
    Apr 2012
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    193

    Default

    You are correct ,the spent case form the other 91/30 will not chamber in 91/30 PU ,becase it needs to be put in a resizing die in order for it to chamber in a differnet gun. Pull the bullet ,dump the powder,, deactivate the primer on a live round and chamber it in your PU you should be able to close the bolt on it .Is your bolt and receiver have matching serial numbers ?If yes you should be fine.

  7. #7
    Join Date
    Oct 2007
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    Get an Okie Field headspace gauge. Still 99% chance of it being fine, but if you have to know...

    +1 on the spent case. That's not a good idea and doesn't tell headspace.
    "It's such a fine line between stupid and clever."
    -David St.Hubbins

  8. #8
    Join Date
    Dec 1969
    Location
    NorthWest Alaska
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    Default

    As well, it could be cosmoline in the chamber, or a dirty case.....it wouldnt help a bit if there were anything in the chamber or on the case before entry.

  9. #9
    Join Date
    Sep 2012
    Location
    Crockett California
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    68

    Default

    +1 on the headspace gauges, but if you just want to "verify" proper ejection, get yourself some "snap caps" I've got some, and recommend then for sure, think I picked up a pair at the last gun show for like $8.

  10. #10
    Join Date
    Dec 1969
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    Upstate New York
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    Default

    +1 on the snap caps I use em in all my firearms.
    Laugh hard and often.

    Gary

  11. #11
    Join Date
    Mar 2011
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    6,123

    Default

    Clean and polish the chamber and throat (with a chamber brush in a drill or emery cloth on a shaped dowel if needed) and clean all around the chamber with a sharp small scraper while looking into the chamber with a very bright light or dried cosmo around it. That cures most sticky bolts.
    Also, carefully but lightly polish the bolt face where it touches the chamber (the bolt ring that wraps around the case rim) as slight corrosion and roughness can make a tight fitting bolt stick at this point as it rotates to headspace. Be careful not to round the bolt face edges -use a flat piece os wood like a popsickle stick or tongue depressor under fine emery cloth so you keep the edge completely flat.
    Somewhat tight headspace is not dangerous if the bolt closes tight but the bolt can be tough to close and open.
    I have some nice nickel-plated Finn dummy shells I use for testing and cycling, found on FleaBay.

  12. #12
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    Apr 2012
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    Michigan
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    Don't worry about gauges until after you try a live round in it....Safely.
    Turbodan - maybe you should sell me your M39 for $100, since its ruined now.

    Phil

  13. #13
    Join Date
    Oct 2012
    Posts
    5

    Default

    Thanks for all of the responses - I will be bringing it to the range to give it a shot (pun intended). I'll post a range report afterwards to see if it is really a problem or not.

    I have already polished the chamber - one of the steps I do in initial prep, as I learned the hard way from the sticky bolt in my first Mosin and I know the bolt/extractor is not the issue (the PU bolt works like a dream in the other Mosin). And my issue with the extraction was not the sticky bolt or the round getting stuck - but the fact that in the PU receiver with both bolts the extractor will latch onto the round - I see the scaring on the back of the round where the extractors are hitting the back of the casing, but not going over the rim (from both bolts). Now this may turn into a moot point as when I fire it the energy from the round might kick the casing back the small distance needed to latch. I guess I will have to do close examination of the casing after I shoot it to see if there are any safety issues.

    So that still leaves the issue I began with: If the Headspace is the problem - how to adjust it?

    I've seen many diagnosis answers for my issue, but no answer as to how to adjust the headspace! Is it even possible?

  14. #14
    Join Date
    Dec 2011
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    Northwest Ohio
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    If you INSIST upon using a live round to check headspace, please do everybody a favor and get hold of a spare firing pin you can cut the tip off, and then assemble the bolt around it before you try anything.

    About adjusting the headspace, the only GOOD way to do it is with a chamber reamer, but you MAY also luck out by playing mix and match with a bunch of different bolt heads.

    Odds are, you are going to find your chamber is just fine if you don't try jamming expanded cases from other guns in there, though.

    If you REALLY feel the need to stick fired cases into a chamber, I would suggest you keep a couple (or several) of such fired cases from each rifle you have, clearly identified as to which rifles they are from. A ziplock baggie full, with the rifle's serial number written on it works for me.

    I HAVE done this fired case thing in the past in order to check on my repair progress on rifles that do things like require undue force to pull back the bolt after firing the round. I have done this most recently on a Yugo K98 Mauser (it is better, but not completely fixed yet). The reason I do this is in that rifle, they seem to be sticky in the same way and require the same amount of force to extract when they get rechambered as they were the first time, at least for a few rechamberings. I suspect on this rifle, it is a bit of chamber wear in the case neck area. I have ALWAYS used fired cases from THAT specific gun, though.

  15. #15
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    The tolerance on rims of 7.62x54R is so great that they cannot be used to check headspace unless you micrometer the rim and shim it properly.

    And you can remove torn cases from any rifle by making a little pry bar out of a piece of scrap brass (NOT STEEL!). Shape it into a chisel shape, push the end under the edge of the case in the chamber and pry up. Then using long thin needlenose pliers (make sure there are no rough edges on the outside of the jaws) grab the pried up piece and begin to wrap the case around the pliers. it should tear and roll around them like an old fashioned sardine can opener. Eventually you'll get enough out to be able to pull or push the case out.
    Last edited by jjk308; 10-17-2012 at 10:54 AM.
    I swear by Jupiter Optimus Maximus .... in the army of the consul Lucius Quinctius Cincinnatus and for 10 miles around it I will not steal anything worth more than a sestertius in any one day.

  16. #16
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    Dec 1969
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    Might have a staredown with the rear of the barrel where the extractor seats when the bolt is closed.......some cosmo, pineneedles, sand, Fly carcass.....anything that might be interfearing with your extractor.

    The best way to adjust headspace, if you find a problem with yours, is to exchange bolt heads.

    Its strange, to me, that a PU could have left referrb out of spec.........

    No dummy ammo?, I would simply load the rifle with live ammo, keep my finger off the trigger and cycle it pointed in a safe direction on my porch before I went anywhere with it, a fired case is no way to check anything on a rifle.Proper ammo is the way to go, at least during a cycling check. Try cycle live ammo when your at the range, before you invest in headspaceing stuffs, time and effort

  17. #17
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    Might have a staredown with the rear of the barrel where the extractor seats when the bolt is closed.......some cosmo, pineneedles, sand, Fly carcass.....anything that might be interfearing with your extractor.

    The best way to adjust headspace, if you find a problem with yours, is to exchange bolt heads.

    Its strange, to me, that a PU could have left referrb out of spec.........

    No dummy ammo?, I would simply load the rifle with live ammo, keep my finger off the trigger and cycle it pointed in a safe direction on my porch before I went anywhere with it, (if a bullet stick in there, remove the bolt immediatly, then get it out) a fired case is no way to check anything on a rifle. Empty cases are expanded and not in the spec you want for a check.

    Proper ammo is the way to go, at least during a cycling check. Try cycle live ammo when your at the range, before you invest in headspaceing stuffs, time and effort

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