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Thread: M&P 15 Sport II; Initial shoot with 68, 69gr bullets

  1. #1
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    M&P 15 Sport II; Initial shoot with 68, 69gr bullets

    Hello
    Today was chores day but managed to get enough time to shoot a couple of groups.
    While I was in town I picked up a box of Federal 223 Rem 69gr Gold Medal Match ammo, figuring if anything loaded with the Sierra 69gr bullet is going to shoot, this stuff should.
    The ammo contains 24.5grs of a ball powder and advertises a velocity of 2950fps.
    https://postimg.cc/gallery/vhy10aqi/

    I was mostly looking for some Sierra 69gr bullets but no one had any. All I could find was some Hornady 68gr HPBTs. What the heck, I’ll try ‘em. Well taking a look at them at the shop, they measured around .983”… That’s long.. The Sierra sample from the G.M. ammo was .898”. A little skeptical now whether the Hornady’s are going to shoot…
    I loaded up five rounds with the Hornady;
    LC brass CCI450 and 26.5grs BL-C(2), seated to 2.242”. I figure if any handload would shoot, this one would. Here is how this went;
    Velocity data taken with an Oehler 33. Screens centered 15' from muzzle
    Target circles are 4".




    Well the G.M. Match ammo shot fairly well considering.. I was expecting them to be a bit faster..
    I’m confident I’ll be able to find a good handload with the Sierra bullet.
    Not so much with the Hornady handload.. I’ll shoot a few more just to see, but I think they are too long for a 1-9 twist. Although the box says they are for 1-9 barrels..

    I ordered some 69gr Sierra’s, they should be here in a week.
    WHY DO THEY CALL IT COMMON SENSE WHEN IT IS SO UNCOMMON?

  2. #2
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    I don't mean to pee on your parade, but those are pretty mediocre groups at 50yds... FGMM is shooting 3moa? I would expect cheap ball ammo to shoot that well.

    If you're looking for accuracy, then why don't you use a magnified optic and some targets smaller than a 4" dot?

    Is your barrel free-floated?

    And pleeeease don't take this the wrong way, but can you shoot accurately?

  3. #3
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    Can I shoot accurately?
    Given an entry level rifle and a 2 MOA RDS and some loads the rifle likes...

    Here is some 62gr loads the rifle seems to like;

    25.5grs W846


    24.5grs AA2230


    25.5grs TAC


    26.0grs AA2460


    The rifle didn't much care for the 62gr factory loads but it really liked the 55gr factory loads;



    That Frontier load put four rounds pretty much in one hole and one flyer..
    The IMI load pretty good.



    American Eagle didn't do too bad either..

    Here are some hand loads;


    24.0grs AR COMP


    25.0grs AA2015


    25.5grs AA2230


    27.5grs CFE223 was ok..


    Can I shoot accurately given the above.. Ok I guess.

    Can this rifle shoot 69gr Sierra's? Don't know yet..
    WHY DO THEY CALL IT COMMON SENSE WHEN IT IS SO UNCOMMON?

  4. #4
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    Quote Originally Posted by RDub View Post
    Can I shoot accurately?
    Really, I meant no offense, but when I see FGMM shooting 3moa, then I assume there's something wrong with the conditions, the rifle, or the shooter...

    And I'm no expert, but if you're trying to load for accuracy, then using a USGI-style M4gery and an unmagnified red dot is like inspecting a car's paint job in a dimly-lit garage...

  5. #5
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    Hello, none taken. I didn't make my intention very clear. I am not 'shooting for accuracy'by definition. I know what this entails and you are correct about attempting to do so with this setup. I am merely exploring what one can expect from a setup like this one with varying bullet weights. It's a no-brainer the 55 - 62 grain bullets would shoot the best in a 1-9" twist barrel. It's the longer ones I am more curious about. How far can one really go and still shoot decent groups. Now that I'm thinking about it, those 69 grain bullets probably are not even stabilizing at 50 yards .. now we are back to the idea that these longer bullets need to be shot at 100-300 yards with some good glass... So there we are.

  6. #6
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    Quote Originally Posted by RDub View Post
    Now that I'm thinking about it, those 69 grain bullets probably are not even stabilizing at 50 yards .. now we are back to the idea that these longer bullets need to be shot at 100-300 yards with some good glass... So there we are.
    Uhhh... I'm no expert, but AFAIK that's not how stabilization works.

    If they're not stable at 50yds, they're definitely not going to be stable as they slow down at 100 to 300yds...


    On the other hand, those 69s are making nice round holes: No keyholing. I don't think instability is your problem.


    I base this on playing with this:

    https://bergerbullets.com/twist-rate-calculator/

  7. #7
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    Well I entered the appropriate data for the Sierra 69 grain bullet, and it said quote; your bullet is flying with full stability you can expect good groups and your BC is optimized unquote.SG=1.70 ..
    Sierra says the BC on that bullet is . 301. Maybe I should shoot those one more time, this time not having worked all day beforehand.

  8. #8
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    Last I remember the 68gr and 75gr Hornady BTHP were the exact same length.

    Unless they changed it in the last few years, you're right in thinking they might be too long.

  9. #9
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    Quote Originally Posted by Bimmer View Post
    On the other hand, those 69s are making nice round holes: No keyholing. I don't think instability is your problem.
    Yep. 1/9 is plenty of spin for 69 gr smk. We shoot 80 gr smks out of a 1/9. 69gr SMKs are not the kind of bullet that needs to "go to sleep". That appies to secant ogive bullets, and even then... that theory has it detractors.
    "You people have too much time on your hands." - scottryan

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