300 Blackout C.O.L / load data question

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  • Donald1818

    Active Member
    Aug 22, 2013
    351
    Baltimore
    Howdy Folks,

    Its been a few years since I have done much reloading, but i am getting back into it.

    I pulled out my 300BO the other day and wanted to reload.

    as i was double checking the websites for load data, I seem to have forgotten what the rules for determining the C.O.L for the blackout are.

    none of the websites really had any information that was useful to me, and they only had a select few projectiles listed, most were not the ones that I currently own.

    the list the projectiles that i currently have for the 300BO:

    125g nosler ball tip #BT3355
    150g Hornady fmj-bt
    150g nosler ball tip #BT3365
    165g nosler accubond
    178g hornady A-max
    180g hornady BTSP interlock
    180g nosler accubond spitzer
    200g nosler accubond spitzer

    again- primarily i am just seeking how to determine the C.O.L data for these, but any and all load data for these projectiles is welcomed.

    also, I am primarily using for powder:
    H110
    Lil-gun

    Thank you ALL, for the help.
     

    K31

    "Part of that Ultra MAGA Crowd"
    MDS Supporter
    Jan 15, 2006
    35,632
    AA county
    You should invest in the Hornady OAL tool, or a like one, to determine the greatest OAL for your own firearm.
     

    RetiredArmyGuy

    Active Member
    Jan 16, 2018
    171
    Pasadena, MD
    One of the oddities of 300 Blkout is that they don’t function well in a standard AR magazine if the ogive of the bullet is seated at or forward of the big indent at the front of the magazine. This indent has a purpose for standard 223 ammunition as it keeps the 223 ammunition from moving forward in the magazine by keeping the neck of the cartridge behind it.

    For light bullets this isn’t normally an issue and the can usually be loaded to magazine length or shorter for better accuracy. For heavier bullets it does become an issue so they have to be loaded shorter so their ogive doesn’t contact this indent. I’ll see if I can post some pictures of the Hornady manual with actual COL based on bullet weight.

    I hope this makes sense.
     

    John from MD

    American Patriot
    MDS Supporter
    May 12, 2005
    22,733
    Socialist State of Maryland
    One of the oddities of 300 Blkout is that they don’t function well in a standard AR magazine if the ogive of the bullet is seated at or forward of the big indent at the front of the magazine. This indent has a purpose for standard 223 ammunition as it keeps the 223 ammunition from moving forward in the magazine by keeping the neck of the cartridge behind it.

    For light bullets this isn’t normally an issue and the can usually be loaded to magazine length or shorter for better accuracy. For heavier bullets it does become an issue so they have to be loaded shorter so their ogive doesn’t contact this indent. I’ll see if I can post some pictures of the Hornady manual with actual COL based on bullet weight.

    I hope this makes sense.

    There is a mod for Magpul where you can sand down the forward guide but, now that they sell 300 BO mags, it isn't worth the trouble. I modified four mags before they started making them and it was hard on the hands. :sad20:
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    I bought the specially-made Lancers. They're labeled with "300BLK" in big bold letters, too, which is good. Would have preferred the Magpuls, but none were available when I was looking.

    As for OAL, it's almost always the longest OAL that will fit in the mag, load smoothly, and not hit the rifling.
     

    Donald1818

    Active Member
    Aug 22, 2013
    351
    Baltimore
    As for OAL, it's almost always the longest OAL that will fit in the mag, load smoothly, and not hit the rifling.

    that's what i was having trouble with, on some of the sites they were using heavier grain projectiles but were using a small COL. that's where i was getting confused.

    I remeasured some old loads tonight and they are mostly all at the maximum length provided there was enough seating.

    I just couldn't remember the basic rules for the COL. i guess im getting old or something.

    Thanks
     

    Donald1818

    Active Member
    Aug 22, 2013
    351
    Baltimore
    You should invest in the Hornady OAL tool, or a like one, to determine the greatest OAL for your own firearm.

    Hey,
    thanks for that recommendation.
    that is a new tool that i have not seen before.

    I will have tot think about it.

    Thanks
     

    RetiredArmyGuy

    Active Member
    Jan 16, 2018
    171
    Pasadena, MD
    There is a mod for Magpul where you can sand down the forward guide but, now that they sell 300 BO mags, it isn't worth the trouble. I modified four mags before they started making them and it was hard on the hands. :sad20:

    I was aware of the MOD but didn’t know they started making dedicated mags. I decided a long time ago to make it work without mods so I didn’t have to worry about it. Everything I load for 300BO works perfectly fine in the standard AR mags. Thanks for the information on the dedicated Magpul mags!
     

    Donald1818

    Active Member
    Aug 22, 2013
    351
    Baltimore
    You should invest in the Hornady OAL tool, or a like one, to determine the greatest OAL for your own firearm.

    Yeah,
    you know, I don't remember seeing this tool just a few years ago when i was reloading before.

    I watched a few you-tube videos and decided to purchase a set.

    Thanks for this help.!!!

    D
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    The Hornady tool is great, but realize that it's not going to tell you what feeds reliably out of your magazine, which is a substantial issue with those big blunt 300AAC subs.
     

    Donald1818

    Active Member
    Aug 22, 2013
    351
    Baltimore
    The Hornady tool is great, but realize that it's not going to tell you what feeds reliably out of your magazine, which is a substantial issue with those big blunt 300AAC subs.

    I feel as if I'm learning all this stuff all over again.

    I don't shoot sub sonic, i don't have a suppressor.
    I think that this will get me closer to where i want to be than where i was before.

    like I said b4. i have been out of the hobby for several years, so there is much to catch up on.

    I love the detail that this hobby offers, I just want to have a good shoot, and/or, hunt.

    years ago- no one talked about measuring this way, it was always COL.

    Thanks for the help.

    D
     

    K31

    "Part of that Ultra MAGA Crowd"
    MDS Supporter
    Jan 15, 2006
    35,632
    AA county
    Yeah,
    you know, I don't remember seeing this tool just a few years ago when i was reloading before.

    I watched a few you-tube videos and decided to purchase a set.

    Thanks for this help.!!!

    D

    I consider it something that should be a basic part of every reloaders gear.
     

    Pinecone

    Ultimate Member
    MDS Supporter
    Feb 4, 2013
    28,175
    I managed to get ONE Magpul .300 BO mag. I would like more, but guess that one 30 round mag of suppressed subsonic is good for HD. :)

    Are the regular Lancers good for .300? I picked up a few at Green Top.
     

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