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Discussion Starter #1
I some test loads with BL-C2 for my Mosin Nagant . Of course using the low end of info from Hodgdon data went to try them out . The after the first shot the bolt was stiff to open and the primer showed signs of high pressure . I walked back to the house and pulled the bullet on a round and double checked the charge and it was ok and the bullet seating depth was good also on the other test rounds . I went and fired another shot and same thing . I stopped and went and pulled bullets on all the other rounds and all checked good , was correct bullet size and brass . I have used BL-C2 with some other calibers with good luck . What am I missing here ? I have been reloading for my Mosin for years with H4895 but have had to change cause of powder shortages .
 

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Never ever heard of a 7.62X43R, would be an interesting round to see. Checked on Hodgdon’s website and found nothing. How about some specifics on the components you used? Maybe something we can see.
 

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I found this that mite help.

The three loads listed used Federal 210-M primers which are a larger rifle match primer, which sort of a light magnum primer.

BLC-2 burn hotter then 4895, which I have ask as to which 4895 are you using, IMR or Hodgdon, and what bullet weight, primer type ?
240049

240050
 

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Discussion Starter #9
Yes H4895 had been my go to powder . But with shortages have had to change to BL-C2. I have read even tho they list a .308 bullet for 7.62x54r it uses a .311 and up and it's suppose to be ok to use same data . Comparing 303 Brit and 7.7 Jap it shows .311 bullet with charges about 42gr . But shows 52gr for .308 in 7.62x54r . I have not found much on BL-C2 in the 7.62x54r . But have tried in my 303 and 7.7 loads with good results and no pressure signs . I first thought maybe read data wrong but was right , and checked charges after pulling bullets and were good , and COAL was good also . I shot some reloads with H4895 after and they shot fine .
 

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Sorry, can’t help you with BLC2, never used it.
My powder for my MNs and many other .30 cal type military rounds I’ve loaded for was always 4064. Probably because I always had it around because I used to load a lot for my Swift and that was the go to Swift powder, that is listed as an alternative powder for just about any other military loads as well.
 

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@soonerfan66 you may have answered your own question. I’d slug the barrel and see where you are. I have a hex receiver 91/30 that slugs at .308 and an M44 that measures .311 so it gets 303 Britt bullets at 312. My RCBS die set came with two differently sized expander balls because of these large variations. If you’re at .308 like mine and cramming a .312 bullet down the pipe it could explain signs of excess pressure.
 

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Discussion Starter #12
I have had this Mosin for long time , was 1st mil surp I bought . It's been slugged and takes a .311 diameter bullet been using them ever since . I have bought pulled bullets for it few weeks back . I checked a few for diameter and they were good . I may go thru the whole bag and double check , I don't know maybe a few bigger ones got in the mix . ??
 

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If there pulled bullets, check if they are concentric and not out of round. A micrometer that reads down to ten thousand would really help.
 

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If you’re having issues and you’re at the minimum charge, increase the charge weight.
Looking at primers isn’t going to tell you much of anything about pressure. If you have a chronograph, run your loads over it and compare your velocities to hodgdons data. That will give you a better understanding of where your pressure is. That’s far more reliable than the good ol’ flattened primer.
 

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If you’re having issues and you’re at the minimum charge, increase the charge weight.
Looking at primers isn’t going to tell you much of anything about pressure. If you have a chronograph, run your loads over it and compare your velocities to hodgdons data. That will give you a better understanding of where your pressure is. That’s far more reliable than the good ol’ flattened primer.
I would be concerned about increasing the charge weight. Though I agree with you that looking at primers is not a way to determine pressure signs because headspacing may cause flattened primers, but the concern is the "stiff bolt". To me , that is a concern.

BL-C2 is a very hot burning powder and depending on the brisance of the primer, the spike in pressure can be a lot faster, I would continue to decrease the charge. What type of primer are you using?
 
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I would be concerned about increasing the charge weight. Though I agree with you that looking at primers is not a way to determine pressure signs because headspacing may cause flattened primers, but the concern is the "stiff bolt". To me , that is a concern.

BL-C2 is a very hot burning powder and depending on the brisance of the primer, the spike in pressure can be a lot faster, I would continue to decrease the charge. What type of primer are you using?
The CUP hodgdon lists for the 150 grain loads(when comparing 30-06 data that lists CUP and PSI) puts the pressures roughly in the mid 50,000psi range. That’s way less than the mosin nagant action is capable of handling.
 

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Discussion Starter #17
I don't have a chronograph (Dear Santa please tell wife) . I am not sure how going with a higher charge could help . I miked and looked at ALL the bullets . What fun . They all seemed to be pretty close to diameter . A few may of seemed out of round a little maybe ,none really jumped out at me just by looking at them . I finally loaded up a test round using the pulled bullets . One more thing I did buy these at a pawn shop . I really didn't know what else to do . When I fired it the bolt opened like normal and the brass came out easy with no tightness . The primer looked just fine , no signs of high pressure . I used the same charge and seating depth . So now I am trying to decide what to do . Cross my fingers and use the rest of the bullets and hope I won't have anymore issues . I tossed the ones that seemed a little off . I thought maybe load a few for 303 Brit and 7.7 Jap to see how they do .
 

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I concur with ms6853 about BLC-2 be a high temperature burning gunpowder. It is also temperature sensitive, but most spherical gunpowders are with the exception of some of the more modern types.

Another way to check chamber pressures is if you have virgin cases is to measure the case expansion at the web just in front of the extraction groove. This is the thickest section of the case. Ideally is should not expand no more then .001”-.0015”. The only tool to do this measurement is done with a blade micrometer that reads to .0000”. The caveat is that this measurement is subject to knowing the hardness of the brass and if the chamber is of a maximum size for SAAMI spec. This type of pressure measurement will only tell about that particular batch cartridge brass.
 
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