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Help me estimate the ballistics of the following...

Discussion in 'Rifle Country' started by ny32182, Aug 7, 2008.

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  1. ny32182

    ny32182 Member

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    I am planning to shoot in a 3 gun match that might require a 300 yard shot on an 8" plate. Unfortunately I have nowhere to practice past 100 yards. I will be shooting a 10.5" Mk18 clone with a 2moa Aimpoint.

    I have been working some loads that I hope will give me the best chance of making the hit. Two weeks ago I was shooting 77gr SMK's at 100 yards. My best load was with 24.3gr Varget. The group was 21 rounds. Deducting one bad flier, the maximum spread of the remaining 20rd was 2.347". I think this is "accurate enough", if I'm not mistaken. I am planning to shoot a bigger batch and zero for this load on Saturday.

    I do not have a chrono, unfortunately. My question is, can anyone take a rough guess at what sort of muzzle velocity I might be getting, and what my holdover might be at 300 yards with a 100 yard zero? Thanks for any input...
     
  2. Art Eatman

    Art Eatman Moderator Emeritus

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    Odds are that zeroing 2" high at 100 yards will put you nearly dead center at 200 and about 6" low at 300.

    (Which holds true for about 90% of all deer cartridges, from around .257 Roberts through .30-'06. :D I just hadda toss that in.)
     
  3. ny32182

    ny32182 Member

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    Thanks... is that true even with the short barrel? I am seating to absolute max length for the magazine, if that helps... 2.26-2.264" seems to be the norm. So far they have all fit in the mag, but just barely.
     
  4. taliv

    taliv Moderator Staff Member

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    it's plenty accurate.

    no experience with 77g smk out of a 10.5" barrel, but it's probably around 2400 fps or so? that'd be my guess.

    in any event, i'd do a 50 yrd zero and then hold about 1/2 to 1 target-width high
     
  5. FreeinAZ

    FreeinAZ Member

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    Buddy with a 10.5 with 55gr ammo is , like Art said above, about 6" low at 300 yards. He has spent a lot of time experimenting with the red dot, and different placement of the dot as a way to holdover. IIRC, you can place the bottom of the dot on the center at 300 yards and be pretty close. I will talk to him today, but I am pretty sure he uses the top of the dot out to 100, then the bottom at 300 in matches.
     
  6. Swampy

    Swampy Member

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    ny,

    With a solid 100 yard zero you will need to come up approx. 3 MOA to hit center at 300 yards.

    Standard Highpower come-ups.....

    Best regards,
    Swampy

    Garands forever
     
  7. ny32182

    ny32182 Member

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    Thanks everyone, I guess we'll see how it goes.
     
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