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  1. #1
    Senior Member Winxp_Man's Avatar
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    Hey I know you would know pretty good about the MK 248 MOD 1 round JF.

    My questions is if I have a throat length total of 3.550" am I good to go for this round ? I know they run out to 3.500".
    shoot to kill not wound !

    Reminton 700 SPS Tactical .308
    Remington 700 Sendero SF II 300 Win Mag

  2. #2
    Senior Member JFComfort's Avatar
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    You should be good. The 220 SMK is a large bullet and not super sensitive to jump. I wouldn't worry so much about the specs of the mod 1 and just work up the load for your rifle. Make the COL as long as your mag will allow to leave room in the case and help drop pressure just a hair. Using a large rifle primer instead of a magnum will help keep pressure in check too. The Mk 248 mod 0 stuff I shot up a couple years ago was loaded in Winchester brass. WCC head stamp "Western Cartridge Company". The load was hard on brass just like I'm sure the mod 1 load is.

    I'll dig around and see if I have any of that stuff left. I included a lot of it when I sold my .300 WM.

  3. #3
    Senior Member JFComfort's Avatar
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    The load I ended up loving was one I worked up with a 208 A-Max. I used Retumbo, WCC brass, FGMM 210M primer with a 3.62" COL. They were leaving my 700P .300 WM @ 3,000 fps. That load turned my rifle into a hammer, it would reach out to 1,550 yards with very little drama. I should have kept that rifle :-(

  4. #4
    Senior Member Winxp_Man's Avatar
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    Im going to get some 220 SMK's and also some H1000 aside from the Retumbo I already have. I will also get some Hornady 208 A-Max rounds online cause I cant find them locally.
    shoot to kill not wound !

    Reminton 700 SPS Tactical .308
    Remington 700 Sendero SF II 300 Win Mag

  5. #5
    Senior Member JFComfort's Avatar
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    Keep us updated on how the load development works out!

  6. #6
    Senior Member Winxp_Man's Avatar
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    I sure will. I just got me some Retumbo, H1000, 220 SMK, and a neck sizing die. I found some Winchester brass 27 shipped which is a pretty good deal.
    shoot to kill not wound !

    Reminton 700 SPS Tactical .308
    Remington 700 Sendero SF II 300 Win Mag

  7. #7
    Senior Member JFComfort's Avatar
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    Some Mk 248 mod 0 stuff. I'm trying to track down some measurements I took from the brass and loaded rounds. Its been a long time since I've shot magnum rifles and all this Mk 248 mod 1 stuff has been getting me excited. I'm considering tracking down a 700P in 7mm Rem Mag but we'll see I get easily distracted.



    Its pretty cool researching the loads the military develops. It started as a Navy project I believe and worked out handy because the Army M24's were build on long actions since the original chambering was going to be .30-06. As we all know they ended up going with .308 Win.



    I dropped the magnum rounds in favor of efficient short action rounds but sometimes I have to admit I miss it.

  8. #8
    Senior Member Winxp_Man's Avatar
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    Dont get distracted and get one :D

    I have a 7mm the 69 model and when the barrel goes out I will supe it up for long range with a trued action and a nice barrel. I was messing with the ballistic calculator and the Swampworks JLK VLD .284 180gr bullets and they are the craziest thing I have ever ran on the ballistic calculator. This dam bullet runs supersonic out to 2000 easily at 3000 FPS. I wonder how much beating that 3000 FPS will give the barrel.
    shoot to kill not wound !

    Reminton 700 SPS Tactical .308
    Remington 700 Sendero SF II 300 Win Mag

  9. #9
    Senior Member Winxp_Man's Avatar
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    Ok so I went out yesterday the 6th of May, and shot 50 various loads of 220 SMK and 208 A-Max. Here are the numbers and they kinda pissed me off.

    Alt- 151 sea level.
    Temp ranged from 79.9* to 83* when I was done shooting for the day.
    Humidity started at 31.8% and came down to 25%
    Bar Pressure started at 29.920 and ended at 29.870

    220 SMK
    76.0 H1000
    Winchester Brass @ 2.610 (New case capacity was 89.48)
    CCI 250 Mag Primer
    COAL from Ogive 2.880 (Which should = 3.450 COAL for the 220 SMK that is)

    2729
    2748
    2769
    2766
    2759

    76.5 H1000

    2802
    2729
    2724
    2826
    2826

    77.0 H1000

    2789
    2770
    2773
    2785
    2794

    This is the same setup with Retumbo powder.

    78.0 Retumbo

    2836
    2823
    2807
    2845
    2800

    78.5 Retumbo

    2800
    2807
    2806
    2822
    2830

    I dont get the variation in the numbers ? I wonder if the primer had something to do with it. I just got some Federal 215M maybe this will give me better consistent numbers.

    Here I changed the bullet to the Hornady 208 A-Max COAL from the ogive was 2.880 but from the tip it was about 3.650

    76.5 H1000

    2842
    2803
    2845
    2835
    2838

    77.0 H1000

    2825
    2846
    2818
    2845
    2833

    These loads are with Retumbo but same 208 A-Max

    79.00 Retumbo

    2958
    2838
    2968
    2884
    2990

    79.5 Retumbo (These loads all had a pretty bad sticky bolt)

    2950
    2869
    2909
    2913

    Again not very consistent with FPS at all. I will try all these loads again with Federal 215M primers and see what happens.

    Joe maybe you can look up some of your old info and give me some input :)
    shoot to kill not wound !

    Reminton 700 SPS Tactical .308
    Remington 700 Sendero SF II 300 Win Mag

  10. #10
    Senior Member JFComfort's Avatar
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    I used a 210M primer instead of the 215M to help drop pressure just a hair. My COL was 3.62" putting the 208 A-Max just off the lans. My brass OAL was 2.62". What scale are you using? How did the neck tension feel when you were seating the bullets?


 
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