Overcharged?

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  • DarrellA

    Jacksonian Independent
    Aug 20, 2013
    1,184
    MD
    These are a few examples of the brass after 3 firings. .308, 42g of Varget, 168g SMK.

    They seem to exhibit signs of being overcharged. I think the primers are cratered and the ejector marks seem excessive.

    42g of Varget is at the low end of the range of charges in my Lyman and Speer handbooks. 41g is the starting load.

    Shot from an AR-308.

    What's the opinion of folks who know more then me - which is almost everyone here!

    Thanks
     

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    lx1x

    Peanut Gallery
    Apr 19, 2009
    26,992
    Maryland
    Maybe just the primer.. soft cup.

    What's the half moon on the cases? dents?


    I load at 41.9gr varget .. that's 2600 fps..

    Max is 43.5gr per sierra manual.
     

    DarrellA

    Jacksonian Independent
    Aug 20, 2013
    1,184
    MD
    Maybe just the primer.. soft cup.

    What's the half moon on the cases? dents?


    I load at 41.9gr varget .. that's 2600 fps..

    Max is 43.5gr per sierra manual.


    Soft cup? Maybe. They are Winchester primers. Do they have a reputation for being soft?

    The marks are, I believe, from the ejector. If I understand correctly, the brass will be smashed back into the ejector leaving that mark if overcharged.

    My Speer manual says 42.0g - 46.0g. Lyman says 41.0g - 45.7g. No matter which manual, I should not be in an overcharge situation, but ... who 'ya gonna believe? The books or your eyes? :-)
     

    PoPo3

    Active Member
    Oct 26, 2009
    364
    Hagerstown, MD
    Have you shot factory rounds out of it? If so, do they look like this? It could be a headspace issue. 42 grains should not be giving you pressure problems. I'm no gunsmith, but I'm guessing excessive headspace.
     

    DarrellA

    Jacksonian Independent
    Aug 20, 2013
    1,184
    MD
    Have you shot factory rounds out of it? If so, do they look like this? It could be a headspace issue. 42 grains should not be giving you pressure problems. I'm no gunsmith, but I'm guessing excessive headspace.

    I have, but don't recall if I saw these signs. I'll pick up another box of factory ammo and see what happens.

    Good idea, thanks!
     

    lx1x

    Peanut Gallery
    Apr 19, 2009
    26,992
    Maryland
    Have you shot factory rounds out of it? If so, do they look like this? It could be a headspace issue. 42 grains should not be giving you pressure problems. I'm no gunsmith, but I'm guessing excessive headspace.
    One possibility..

    I haven't seen those kind of case mark on my lr308.
     

    Seabee

    Old Timer
    Oct 9, 2011
    517
    Left marylandistan to NC
    It could be several things. The cratered primer is likely excessive space around firing pin as already stated. I have a bolt rifle that does that too even though loads aren't hot. Are you getting a lot of case stretch? If so, it could be a head space issue. Have you tried headspace gauges in it? Could also be just soft brass. It be just about anything but the load, as noted it isnt a hot load.
    Case length before and after firing may help us
     

    Mike3888

    Mike3888
    Feb 21, 2013
    1,125
    Dundalk, Md-Mifflin,Pa
    Op what barrel do u have. From reading your post as others have said that load is not hot. Those swipes are pretty severe. I'm no gunsmith either but those swipes could possibly be over pressure signs. Maybe over gassed. Are you running an adjustable gas block? If factory ammo don't do that, I think you are not sizing brass correctly. I had that issue on a 6.8. Hope ya figure it out.
     

    DarrellA

    Jacksonian Independent
    Aug 20, 2013
    1,184
    MD
    I'm getting about 6 thousandths of stretch after firing.

    I use the Hornady headspace gauge bushing to check size. I just checked some new Norma and Winchester brass I have on hand and I notice the Norma is about 1-3 thousandth shorter than the Winchester. I set my sizing originally to match the Federal GMM factory ammo I had, which happens to be the same as the Winchester brass.

    I'm more confused now than when I started! :-)
     

    DarrellA

    Jacksonian Independent
    Aug 20, 2013
    1,184
    MD
    FWIW, the gun is built from an 80% lower and an Alpha Shooting Sports complete upper.
     

    E.Shell

    Ultimate Member
    Feb 5, 2007
    10,245
    Mid-Merlind
    Those loads are WAY too hot for that brass...

    ANY ejector mark is very bad news and indicates that you are exceeding the yield strength of the brass and beginning to extrude case head material into the bolt face ejector bore.

    There may be something else going on, because the load you list should not be excessive, but it clearly is and you should not shoot any more at, above or near this charge weight until you fix this.
     

    lx1x

    Peanut Gallery
    Apr 19, 2009
    26,992
    Maryland
    Just curious.. what's the c.o.a.l. of the reloads..

    Never match the factory seating depth.. they use different powder etc.

    I'd follow eshell advise. He's the resident expert.

    Have used Winchester brass.. and never seen that on my reloads.
     

    dist1646

    Ultimate Member
    May 1, 2012
    8,758
    Eldersburg
    Those loads are WAY too hot for that brass...

    ANY ejector mark is very bad news and indicates that you are exceeding the yield strength of the brass and beginning to extrude case head material into the bolt face ejector bore.

    There may be something else going on, because the load you list should not be excessive, but it clearly is and you should not shoot any more at, above or near this charge weight until you fix this.

    THIS!
     

    TGR

    Active Member
    May 20, 2009
    170
    Harford County
    Looks like signs of overpressure. But then again, maybe not. My Carbine does the exact same thing to the primers with all loads, factory or reloads. Like others said, it's caused, in my case anyway, by an overly large firing pin hole in the bolt. Perfectly normal for my setup, and maybe yours too.

    The case markings are more concerning. Those show the classic signs of brass extruding into the recess due to pressure. What's causing it is what needs to be answered.

    I would build up the load from scratch again using a known starting load from a book, with trimmed brass and COAL as listed in the book, as opposed to matching a factory shell.

    Good luck. Be safe.
     

    Sticky

    Beware of Dog
    MDS Supporter
    Mar 16, 2013
    4,501
    AA Co
    Those loads are WAY too hot for that brass...

    ANY ejector mark is very bad news and indicates that you are exceeding the yield strength of the brass and beginning to extrude case head material into the bolt face ejector bore.

    There may be something else going on, because the load you list should not be excessive, but it clearly is and you should not shoot any more at, above or near this charge weight until you fix this.
    Agree 100%! I never get ejector flow like that, too much something. I would suggest getting hold of a hornady headspace gauge tool (I have one if you want to come by and use it) to determine the 'proper' length for that projectile and your rifle. Something isn't right, your load isn't too hot, but the length being too long for your chamber could explain that. Fix it or don't shoot reloads til you do. ;)

    There can be reasons for cratering of the primer besides too hot a load, as TGR mentioned (too much room between the firing pin and the hole in the bolt face). That's not too much of a concern, but the ejector flow (marks) are a bad sign, very bad..
     

    Sticky

    Beware of Dog
    MDS Supporter
    Mar 16, 2013
    4,501
    AA Co
    Are you full length sizing the brass? Do you have a case gauge to check it after sizing?

    - edit... I reread your posts and it sounds like you have a case gauge to check the resized brass.. This should tell you, but you can also measure the shoulder setback to be sure it's being properly resized. Setting the sizing die off a loaded case is not the proper way to set it up. ;)
     

    GUNSnROTORS

    nude member
    MDS Supporter
    Jun 7, 2013
    3,620
    hic sunt dracones
    Just checked my Sierra manual (edition V). Varget starting load for the 168g SMK is 38.7g. Max is 43.5g, as lx1x posted earlier.

    Agree with Mr. Shell, back off 2 or 3 grains and restart your load development.
     

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