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Thread: Mosin-Nagant Overpressure?

  1. #1

    Mosin-Nagant Overpressure?

    Just fired my first ever reloads for Mosin-Nagant. 180gr FMJ over 42.5 grains of IMR4895 & CCI 250 primers. Barrel slugs at .313. These bullets were .311. New PPU brass. Books say this should be middle or lower middle.

    Do these primers look like theres initial signs of an overpressure?

    Thanks
    Last edited by franklin_m; 01-25-2020 at 06:49 AM. Reason: Corrected "PPI" to "PPU"

  2. #2
    Boolit Master redhawk0's Avatar
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    Not to me. They look to be within the normal range.....when its over pressure the rounded edges, of the primer where it meets brass, will fill in. (have a right angle in some extreme cases)

    redhawk

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  3. #3
    Quote Originally Posted by redhawk0 View Post
    Not to me. They look to be within the normal range.....when its over pressure the rounded edges, of the primer where it meets brass, will fill in. (have a right angle in some extreme cases)

    redhawk
    Thanks. I was worried about that little bit of "cratering" ... most easily seen on the middle one. That rolling up of the metal at the edge of the divot created by the pin.

  4. #4
    Boolit Master
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    That Cratering around the Dent in the primer is from an Oversized hole in the bolt face where the firing pin fits.
    It is a common problem or should I say Condition on Mosin Nagants.
    I have never had an issue with any of mine that had a Wallered out hole , or an undersized firing pin.

  5. #5
    Boolit Master redhawk0's Avatar
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    Yeah...LAGS is right. I get cratering like this on several of my older firearms. The primer hole gets larger, or sometimes even out of round due to use/age. Some of the older shotguns had primer hole "inserts" that could be replaced (O/U and SxS) Some revolvers too. What you're showing is totally normal and you're good to go.

    redhawk

    The only stupid question...is the unasked one.
    Be Alert....we need more lerts.
    Not all who wander....are lost.

    If more government is the answer, then it was a really stupid question. - Ronald Reagan

  6. #6
    Thanks guys. These are literally my 21st, 22nd, and 23rd reloaded shells. The first 20 were in a Remmy 700 .30-06. I'm just trying to be super cautious. Results were decent enough, and better than the MilSurp! See pic:
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  7. #7
    Boolit Master
    Remiel's Avatar
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    If you are interested there is a guy that for a bushing job to mosin bolt heads to fix the cratering issue. His name is Grimstood Desh, I found him in the mosin modders on facebook.and he has a channel under his name on you tube

    Sent from my SM-G920V using Tapatalk

  8. #8
    Boolit Master 44magLeo's Avatar
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    On mine most anything I throw together for a load shoots better than the surplus stuff. I think the main reason is we are more accurate with the powder. I have torn down some surplus rounds and measured the powder charges. Some vary as much as 1 gr. Keeping the charge within .1 grs has to help.
    Might want to try Hornady's bullets. They are .312. They shoot well in mine. They are 150 gr SP's.
    I also have some Speer 150 gr hot core at .311 and some Seirra 180 gr GK at .311.
    Leo

  9. #9
    Boolit Master
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    Here's a link to his video on a savage bolt bushing job. https://youtu.be/OtPmU7diLME

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  10. #10
    Boolit Grand Master


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    That is a mild pressure load.

    I have pressure tested (Oehler M43 PBL with Finn M39) a bit of 7.62x54R, both milsurp and commercial, and found Winchester 180 factory, Norma 150 & 180 factory and most "modern" milsurp will run 43,000 to 52,000 psi. I load 46 gr H4895 (Norma cases w/WLR primers) under the Sierra 180 gr .311 SP and 46.5 gr H4895 under the Sierra 174 gr .311 MK. they rune 46,500 psi and 44,200 psi out of my Finn M39.....[2606 and 2666 fps muzzle velocity].

    Your load is fine.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
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  11. #11
    Boolit Master
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    I did make a firing pin Sleeve Bushing for one of my Rather well Worn bolt heads.
    It wasnt much more than a section of Brass Tubing silver soldered into the trued up firing pin hole.
    It worked fine , and never came loose.
    A friend of a friend is still shooting that rifle as far as I know.

  12. #12
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    I would REALLY rather see a reasonable amount of reality checking, almost to the point of mild paranoia is fine, in new reloaders - Pretty sure others here feel the same.

    A low pressure load won't damage your gun - or you - and won't make you a statistic or create any problems, provided you put enough powder in that it's not a dud. Good to see you checking as you learn!

  13. #13
    Quote Originally Posted by Mr_Sheesh View Post
    I would REALLY rather see a reasonable amount of reality checking, almost to the point of mild paranoia is fine, in new reloaders - Pretty sure others here feel the same.

    A low pressure load won't damage your gun - or you - and won't make you a statistic or create any problems, provided you put enough powder in that it's not a dud. Good to see you checking as you learn!
    Thanks. I'm naturally very detail and process oriented. Plus I'm not doing huge numbers, so no pressure to "churn and burn" when it comes to reloading. I tend to check, recheck, and check again. The Remington rounds were perfect. Nice primers, didn't get flattened, and clean firing pin marks. So when i saw these at the range yesterday, I thought it wise to get a second, third ... etc. opinion.

  14. #14
    Boolit Master rmcc's Avatar
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    Just an FYI, sometimes you will get primers that back out from TOO low pressure in your load. Coupled with a little extra headspace (even though within normal range) and low pressure, the cartridge case sticks to the chamber walls and is still holding after the pressure threshold within has dropped. The result is a backed out primer and the first thing you think of is HIGH pressure! Another sign is a lot of soot around mouth of case in a low pressure load. OOPs. I digress! Welcome to a lifelong, rewarding pastime!!

    rmcc
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  15. #15
    Boolit Grand Master

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    franklin_m I think your loads are probably fine and what others have said about the bolt head being wallered out is probably the culprit. I still "read" primers but think in reality it is akin to reading tea leaves. I was wondering what the inside neck diameter of one of those cases measured, that would make you a good starting point for cast bullet diameter. You possibly could use one of the Remington cases to measure also but would have to make sure all of the crimp got blown out to full diameter, they usually don't.
    Hell, I was there!

  16. #16
    Boolit Bub
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    Quote Originally Posted by franklin_m View Post
    Thanks. I'm naturally very detail and process oriented. Plus I'm not doing huge numbers, so no pressure to "churn and burn" when it comes to reloading. I tend to check, recheck, and check again. The Remington rounds were perfect. Nice primers, didn't get flattened, and clean firing pin marks. So when i saw these at the range yesterday, I thought it wise to get a second, third ... etc. opinion.
    I tend to be the same way. Been dealing with that kind of thing as I develop my 45 ACP loads and analyzing what I'm seeing.

    The only thing I'd have to add to what others have said is to ask if you've checked your firing pin protrusion. I'm betting it's fine, but some folks don't realize that it can be adjusted on a Mosin and how to check it.

  17. #17
    Everyone ... thanks for the advice, I'll do all of the above. Actually, there is a bit of smoke coloring around the necks, both on the Remmy and the Mosin. Given that I'm in the middle / low middle range for powder in each of those loads, I'll measure now, then bump them up a bit and measure after that firing. I'm using Lee Hand loader for these two, which neck size only, this will minimize variables some as well.

  18. #18
    Boolit Grand Master


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    franklin m

    The lee loader is fine as are your loads. Bumping the load up a bit with 4895 might improve the accuracy. To many who only shoot at short range because of range restrictions (50, 100 or 200 yards) find such loads entirely adequate. I shoot at longer ranges with mine and prefer to develop loads that match and are regulated to the rear sight range settings. For example the 180 gr Sierra SP load mentioned replicates the Finnish "D" load of the '30S which the rear sight on my M39 is regulated to. I use the 174 Sierra MK load in my M91/30 sniper rifle. With the PU scope properly zeroed to it I regularly shoot out to 1000m with it and can consistently hit an "E" target (US military kneeling target).

    Were I to hunt with a MN I would use the 180 Sierra SP load or for factory; Winchesters 180 gr SP load which is loaded with a .311 bullet over extruded powder. It runs 2556 fps at 45,900 psi out of my M39. It runs 2615 fps out of the M91/30 sniper and shoots right at moa for accuracy. As your MN appears to be a M44 the Winchester load runs 2415 fps out of my Type 53 (Chicom version of the M44)

    BTW; the Hornady 150 gr .312 SPs are excellent and very accurate for duplicating the "L" type ammunition.

    And .31 cal cast bullets also shoot very, very well in MNs.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  19. #19
    Larry,

    Thanks so much. Actually I want to hunt with it next season. I think it would be cool to use a vintage rifle to harvest some venison. My biggest challenge is I have more vintage rifles than seasons and tags!

  20. #20
    Boolit Buddy
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    franklin,

    Why are you using CCI 250 (magnum) primers for such a mild load of IMR 4895 powder? Where did you get that data? Your primers look ok to me.

    Adam

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check