odd issue with 300 BO

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  • I formed about 1200 cases from LC 556 brass. sized, cleaned, primed and started loading First step in loading is dropping my cases into a case gauge just to make sure they will feed...So I charge and seat the bullet, drop it back into the case gauge and about 1 in 5 will no longer drop all the way in...

    I removed the decapping rod and ran them back through the sizer and they fit again. It seems odd.

    Formed FC brass
    10 GRN H110
    Berry's 220 GRN Pill
    CCI Small Rifle Primer

    2.23" Overall length.
     

    Clippers69

    Member
    Mar 7, 2011
    59
    300 BO

    Did you bell the case mouth? I bell the mouth on my casings as I also use Berry's plated bullets. I found out that the case mouth would shave the bullet when seating and leave shavings around the case mouth. I belled the cases using a Lyman bell die for an M1 cartridge and it works great. I then removed the bell using a Lee die and re-sizing the case mouth back to specs. The Lyman die makes loading a breeze. My cases are formed from LC brass.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,815
    Are the bullets measuring out at .308?

    I would try a different bullet before anything else. A higher quality bullet, to be sure.

    I load Gallant 220gr coated bullets for my plinking 300blk ammo. They say not to size, but if I don't, no way would they drop into my Sheridan gauge. I size them in a Lee sizer and they shoot fine.
     

    85MikeTPI

    Ultimate Member
    Jul 19, 2014
    2,699
    Ceciltucky
    I formed about 1200 cases from LC 556 brass. sized, cleaned, primed and started loading First step in loading is dropping my cases into a case gauge just to make sure they will feed...So I charge and seat the bullet, drop it back into the case gauge and about 1 in 5 will no longer drop all the way in...

    I removed the decapping rod and ran them back through the sizer and they fit again. It seems odd.

    Formed FC brass
    10 GRN H110
    Berry's 220 GRN Pill
    CCI Small Rifle Primer

    2.23" Overall length.

    Is it LC NATO or FC?

    I've had one NATO head stamp and two FC versions with thick
    Necks and won't gauge after seating a boolit..
     

    Melnic

    Ultimate Member
    MDS Supporter
    Dec 27, 2012
    15,281
    HoCo
    Take case measurements before and after loading

    If you have a seating die that can roll crimp make sure it’s backed out enough not to crimp and if not already try to use use a factory crimp die

    What is the OAL you are targeting and what bullet?


    Sent from my iPhone using Tapatalk
     

    atblis

    Ultimate Member
    May 23, 2010
    2,011
    Typically, sizer dies undersize the neck considerably, and then expand the neck with the decapper rod. If you ran a loaded round through, the bullet in the neck was also resized.
     
    Take case measurements before and after loading

    If you have a seating die that can roll crimp make sure it’s backed out enough not to crimp and if not already try to use use a factory crimp die

    What is the OAL you are targeting and what bullet?


    Sent from my iPhone using Tapatalk

    2.23 OAL and the bullets are .308. I think I know what's going on. The strange part is it doesn't happen to all of them..just relatively few have the issue. I'm going to try to flare the necks before seating. Thanks
     
    Did you bell the case mouth? I bell the mouth on my casings as I also use Berry's plated bullets. I found out that the case mouth would shave the bullet when seating and leave shavings around the case mouth. I belled the cases using a Lyman bell die for an M1 cartridge and it works great. I then removed the bell using a Lee die and re-sizing the case mouth back to specs. The Lyman die makes loading a breeze. My cases are formed from LC brass.

    https://www.amazon.com/Lyman-30M1-Carbine-Neck-Expanding/dp/B0063I1FFW

    this?
     

    Major03

    Ultimate Member
    My bet is that it is a little bit of two things going on.

    1) Those berry's plated bullets are great plinking bullets, they're cheap and they work pretty good for what you pay for. They are however inconsistent in diameter. As others have said, resize to .308 (I also use a cheap Lee resizing die...works great, and I haven't seen any downside to doing it accuracy wise...not that Berry's are match quality anyway).

    2) Resized brass case walls vary in thickness. LC generally resizes to 300 BLK pretty well, definitely with less issues than other headstamped brass. However, you'll still have more variance from case to case in what used to be the case wall and what is now the case neck than in commercially bought 300 BLK brass. Combine that with variance in the bullet diameter, and you'll get chambering issues.

    Resizing your bullets is probably the quickest, least painful way to fix the issue. Other fixes would include, tossing the brass that doesn't work (after deconstructing it to save your powder and/or bullet) or neck sizing and/or reaming all of your brass that you converted to a consistent neck thickness. That's a serious endeavor, but would also come with the advantages of more accurate brass (more consistent neck tension).

    One last thought...the Sheridan gauge is great, BUT is reflective of a tight match chamber. I have a tight match chamber, so I rely on it. However....if you have looser chamber tolerances it MIGHT not be a problem depending on how far off it is. YMMV.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,815
    My bet is that it is a little bit of two things going on.

    1) Those berry's plated bullets are great plinking bullets, they're cheap and they work pretty good for what you pay for. They are however inconsistent in diameter. As others have said, resize to .308 (I also use a cheap Lee resizing die...works great, and I haven't seen any downside to doing it accuracy wise...not that Berry's are match quality anyway).

    2) Resized brass case walls vary in thickness. LC generally resizes to 300 BLK pretty well, definitely with less issues than other headstamped brass. However, you'll still have more variance from case to case in what used to be the case wall and what is now the case neck than in commercially bought 300 BLK brass. Combine that with variance in the bullet diameter, and you'll get chambering issues.

    Resizing your bullets is probably the quickest, least painful way to fix the issue. Other fixes would include, tossing the brass that doesn't work (after deconstructing it to save your powder and/or bullet) or neck sizing and/or reaming all of your brass that you converted to a consistent neck thickness. That's a serious endeavor, but would also come with the advantages of more accurate brass (more consistent neck tension).

    One last thought...the Sheridan gauge is great, BUT is reflective of a tight match chamber. I have a tight match chamber, so I rely on it. However....if you have looser chamber tolerances it MIGHT not be a problem depending on how far off it is. YMMV.

    I too shoot through a match grade barrel(Rainier Ultramatch) with a very tight chamber, hence the use of the Sheridan.

    This was my go-to before I found a reliable source(s) for LC brass, which is pretty much all I use in my BO. It pretty lays out what is preferred brass for forming 300 BO and what would be considered undesireable:

    http://www.300blktalk.com/forum/viewtopic.php?f=141&t=88599&sid=c86a2286869114986a7eac5bdd057f20
     
    I too shoot through a match grade barrel(Rainier Ultramatch) with a very tight chamber, hence the use of the Sheridan.

    This was my go-to before I found a reliable source(s) for LC brass, which is pretty much all I use in my BO. It pretty lays out what is preferred brass for forming 300 BO and what would be considered undesireable:

    http://www.300blktalk.com/forum/viewtopic.php?f=141&t=88599&sid=c86a2286869114986a7eac5bdd057f20

    All of the brass I used to form the cases was LC since I have close to 50,000 5.56 LC cases. The only exception is I did have a couple hundred genuine Remington 300 BO cases but I used those for 110s with zero issues. I ordered a flaring die and I am going to try that. As far as inconsistency in bullet diameter with the Berry's I don't really see any. I mic'ed a few dozen and they appear to be consistent. Can you even resize plated bullets?
     

    Doco Overboard

    Ultimate Member
    All of the brass I used to form the cases was LC since I have close to 50,000 5.56 LC cases. The only exception is I did have a couple hundred genuine Remington 300 BO cases but I used those for 110s with zero issues. I ordered a flaring die and I am going to try that. As far as inconsistency in bullet diameter with the Berry's I don't really see any. I mic'ed a few dozen and they appear to be consistent. Can you even resize plated bullets?

    Just because your bullets are consistent doesn't mean that when they are seated the neck tension isn't collapsing the case on one side a very slight amount.
    Because your case gauge is a cylinder, if one side becomes shorter the other side becomes longer to a certain extent.
    On some of those cases when they enter your gauge the long side could be making contact with the very slight shoulder that I just seen on a Sammi drawing effectively reaching HS only on one side of the cartridge. HS appears to be .010 and because that little shoulder is an angle the problem could be that measurement and not the diameter of the case mouth not allowing it to completely make depth in our gauge. WHich consequently is not your chamber just that the cartridges you are making will fit in the smallest chamber you are likely to encounter and so on.

    Make a few dummies-no powder or primer, soot them and drop them carefully in your gauge to see where the interference is actually occurring. Check to see if they are straight.
    Te above writer is correct about case neck concentricity and tension and almost hit I thught it but he never said the case is getting crushed on bullet seating unless I mis read his problem description.

    Maybe this will help maybe not good luck getting it sorted out.
     
    OK all this about tight chambers got me thinking. When I was a kid my uncle reloaded almost all of his own ammo. I don't recall him ever buying a box of factory anything. His deer rifle was a Remington 7400 in 30-06. It just occurred to me that he would size his rounds twice. Once in the die and after loading them by chambering them one at time by allowing the bolt to slam shut. I know it sounds strange. SO I went down to the safe and pulled out my ARES SCR chambered in 300 BO (Primary Arms upper) and although some were a little tight, they all chambered and ejected without getting stuck. I'm going to work on perfecting them but there is a lot of info here to try. It does look like they will function.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,815
    OK all this about tight chambers got me thinking. When I was a kid my uncle reloaded almost all of his own ammo. I don't recall him ever buying a box of factory anything. His deer rifle was a Remington 7400 in 30-06. It just occurred to me that he would size his rounds twice. Once in the die and after loading them by chambering them one at time by allowing the bolt to slam shut. I know it sounds strange. SO I went down to the safe and pulled out my ARES SCR chambered in 300 BO (Primary Arms upper) and although some were a little tight, they all chambered and ejected without getting stuck. I'm going to work on perfecting them but there is a lot of info here to try. It does look like they will function.

    Good idea. You might even load some uncharged, smudged rounds for this as well...just to see what's going on inside the chamber, as DoCo suggested.

    Also. What press are you using? Don't think that has been discussed anywhere in this thread(unless I missed it:o).
     

    John from MD

    American Patriot
    MDS Supporter
    May 12, 2005
    22,731
    Socialist State of Maryland
    I agree with several other posters. Plated bullets are definitely not target grade. I too have had to size them to get them somewhat uniform even in my .44s as some would give me case bulges. A Lee sizer works just fine and, if you use a Lee hand press, you can watch TV while resizing the bullets. :party29:
     
    Good idea. You might even load some uncharged, smudged rounds for this as well...just to see what's going on inside the chamber, as DoCo suggested.

    Also. What press are you using? Don't think that has been discussed anywhere in this thread(unless I missed it:o).

    Lee 3 holed turret press with Lee dies. Same press i've used for 35 years. I have 2. One dedicated rifle and one dedicated for pistol ammo.
     

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