308 Loads Advice

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  • grahamsy2k

    Sharpshooter
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    6   0   0
    Jul 24, 2012
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    Terre Haute
    I've searched the interwebz for awhile looking for what others are loading for their 20in barrel bolt gun. Since I haven't found much I thought I could help someone else by sharing mine.

    Remington 700 w/ 20in barrel 1-10 twist
    168 sierra MK
    42.0gr of IMR 4064
    COL 2.800
    Win Primers
    Velocity averages 2500 10 feet from muzzle

    I can get extremely good groups out of this. My problem is the velocity. Applied Ballistics says it goes subsonic a little after 800yds.

    My other problem is that loads of 43.0gr of 4064 runs awful through my gun.

    Should I start from 42.0 and work my way up and stop when my groups start to open up and hope my velocity increases enough?
    Or should I go down on bullet weight?
    Or not worry about it?

    If you have a 20in barrel please share what you loading.
     

    avboiler11

    Master
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    13   0   0
    Jun 12, 2011
    2,950
    119
    New Albany
    https://rifleshooter.com/2016/12/30...ra-168-gr-matchking-with-imr-4064-and-varget/

    Hodgdon book max for 4064 and a 168gr SMK is 45.9gr; you've got plenty of room to step on your load. If 42.0gr shoots well for you, OCW says you should hit the next highest node around 43.3gr and another around 44.5. Definitely run an OCW and see what your rifle likes.

    Since you've already got 4064, I would recommend getting a box of 175gr SMKs and duplicate M118LR/Mk316 with 41.7gr. The 175 likely won't give up too much velocity to the 168, but it will work better at longer ranges than the venerable 168 (and when it goes transonic, it will transition predictably).

    In the AAC-SD I used to own, I used a 168gr ELD-M over 45.7gr Varget in Winchester brass, lit by a WLR or CCI-200. This load gave me 2646fps across the Magnetospeed, is under Hodgdon book max for a 168 with Varget, and showed no pressure signs.

    44.4gr Varget under a 168 Amax/ELD duplicates the Hornady 168gr TAP red box load, and gave me 2550fps from the same AAC-SD.
     

    teddy12b

    Grandmaster
    Trainer Supporter
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    40   0   0
    Nov 25, 2008
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    The 168gr matchkings have been the gold standard of precision shooting out of a 308 for decades. Lately the 175gr matchking has gained a lot of traction. Lots of guys get great results using varget for their powder. If I get serious with long range shooting with a particular caliber I buy nothing but Lapua brass. There's other good stuff out there, but buy the best once and cry once. Make sure you're using Federal Match primers. I've seen guys cut a group in half at 500 yards by switching the primers only. Sounds a little crazy that a primer would have that much effect, but the farther out you shoot the more those things come into play.

    Personally, I shoot the heaviest bullet I can get in that caliber. If you want a good example, run some software numbers on a 168gr matchking at 2,600FPS and a 200gr matchking at 2,600FPS. That Little bit of extra weight has enough momentum to carry the bullet down range. The elevation adjustment cuts 5' - 6' off at 1,000 yards, the wind deflection is nearly cut in half, and the energy on target just about doubles. All from just using a heavier bullet. I did this exact thing in a 30-06 and loved the results. Long story short, heavier bullets translate into less needed adjustments and less adjustments means less room for error.

    A good thing to do before buying a bunch of bullets to reload that may completely suck in your rifle is to buy that bullet in factory loaded ammo. If it groups horribly with a factory load, it's probably going to group horribly in your reloads unless you get really lucky somehow.

    With your concerns about the bullet going subsonic, that doesn't mean the bullet stops. All that means is that you have to learn a little more and shoot a little better farther out. It drives me nutts that guys think a bullet stops once it goes transonic. Not trying to brag, but I've hit steel with 18" heavy barreled 308 gas guns that according to the internet shouldn't be allowed to happen, and I really don't believe I'm that great of a shot. For a really good lesson on this, buy the magpul precision rifle DVD and watch those guys beat up steel targets at 1 MILE with a 16" gas gun. Don't sell your rifle or the 308 short.
     

    grahamsy2k

    Sharpshooter
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    6   0   0
    Jul 24, 2012
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    Terre Haute
    I've been referencing an old PDF of sierra's that says 43.3 is the max load for 168smk. How much more room do I have after that?

    43.0 gr of 4064 puts me around 2560, but shoots horribly. Would 43.3 be much different?
     

    teddy12b

    Grandmaster
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    Nov 25, 2008
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    According to the Sierra Bullet Infinity software the max safe load is 43.4gr of IMR 4064 in a 308 with a 168gr matchking.

    There's a lot of different sources for reloading data online, and from different manufacturers. Personally, I don't really care to play the game of wondering how fast I can get a bullet going without my rifle turning into a giant hand grenade in my arms right in front of my face. To each their own though. Having said that, I will also mention that I really doubt any manufacturer is going to put out unsafe data and if anything they'll be a little conservative with what they put out just to cover their own rear end.

    Pressure signs are a pierced primer, it'll look like a little black dot or spot in the primer. Extremely flattened primers, cracks in the brass, excessive burn looking marks on the brass. Lots of good youtube videos on that just to give you a better visual.
     

    sloughfoot

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    26   0   0
    Apr 17, 2008
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    Huntertown, IN
    Kevin Thomas of Sierra introduced the 175 HPBT Sierra over 20 years ago, amongst a lot of fanfare, so that the .308 chambered M1A was viable beyond 800 yards. The m1A has a 22 inch barrel and prior to that we were using the 168 out to 600 yards and the 180 beyond that.

    The 168 simply is not viable beyond 800 yards. The 155 Palma is and also the 175. The 168 was designed for use in 300 meter International matches. It excells in that use.

    The load for the 175 was settled at 41.5 grains of IMR4064 with OAL length of 2.80 in once fired LC brass. No pressure worries no matter how hot it is outside. And was used by hundreds if not thousands of 1000 yard competitors.

    There was a multi page article about it in Precision shooter in the 90's.

    Please just select the appropriate bullet instead of considering going into dangerous pressure territory.
     
    Last edited:

    Broom_jm

    Master
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    Dec 10, 2009
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    A lot of reloaders will cross-reference data from both the bullet and powder manufacturer. If Sierra says 43.3 is max, but other sources say 45 is max, you can be reasonably certain that 44 grains is safe, but it really just depends on your rifle and the feedback it's giving you.

    OCW is a better way of determining a quality load recipe than a ladder test. You use less components in the process and don't run the risk of a "touchy" load.

    Are you shooting a lot past 800 yards? If 1,000 is your goal, it's well-established that the 168gr SMK isn't the right bullet, from a 308 Win.
     

    Notalentbum

    Expert
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    4   0   0
    Jun 12, 2013
    1,330
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    Indy westside
    I went through this last summer. I'm shooting both 168g SMKs and 168g Hornadys out of my Savage 11VT. 40.0g of 4064 was my rifle's sweet spot. I went from 39.0 to 43.0 where I started seeing pressure signs. I had very good groups at 41.8g also. I did not see any other promising loads in the range. I don't have a chronograph so I never looked at velocity. If I was wanting max velocity, I'd experiment more with the 41.8 load but the 40.0 was plenty close for me.
    In fact, I need to load up a box for the shoot at Sgreens place next month.

    Matt
     
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