MK 248 MOD 1 .300 Winchester Magnum Round

Discussion in 'Reloading' started by magnum, Oct 12, 2011.

  1. magnum

    magnum Well-Known Member

    Messages:
    48
    Joined:
    Apr 24, 2004
    Anyone know the components of this load?

    All I can find out from the web is, Sierra 220gr GMK at 2,850 fps (out of the XM2010's 24" barrel)
     
  2. backwoods83

    backwoods83 Well-Known Member

    Messages:
    2,206
    Joined:
    Jan 8, 2011
    The only further info I have is what I've read and it stated LC, Fed, or WCC cases H1000 and Fed215Ms, no statement of powder charge weight but probably 75-77grns.
     

  3. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    FC military Brass (FC 12)
    FC 215 Match Primer (crimped)
    H1000 at 77.7
    220 MK bullet

    3.500 COAL

    Warning!

    To try to dupicate this load you might run into blown primers because they crimp the primers in.
    Very hot load.......suggest reduce load to 76.5 to 77.0
     
  4. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    Correction FC does not crimp the primers in the MK 248 Mod 1 ammo, but they have halted all production due to excessive pressure, same problem they had with M118LR.
    I guess they will reduce the load
     
  5. Lefty7mmstw

    Lefty7mmstw Well-Known Member

    Messages:
    4,280
    Joined:
    May 13, 2012
    You'll probably get better speed with rl25 or retumbo than h1000, but both will be compressed charges. Factory load duplication attempts are always a bit off to me. You are running custom tailored ammo for your rifle (by handloading for it), why whitewash it with a reconstituted factory load??
     
  6. Nomosendero

    Nomosendero Well-Known Member

    Messages:
    1,079
    Joined:
    Jan 17, 2005
    I hear that RL33 is a dense powder, which could be good for a case like the 300WM, where it would normally be a bit slow, but if you can get more in than say retumbo, it could be interesting, havn't tried yet.
     
  7. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    Reloader 33 in 300 WM to take advantage of it you will need a longer barrel than 26"
     
  8. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    Correction to above load FC uses Fed 210M primer (not crimped)
     
  9. MagnumManiac

    MagnumManiac Well-Known Member

    Messages:
    1,002
    Joined:
    Feb 25, 2008
    If you want an accurate load, try 79gr of RE25 with a 200gr Accubond.
    This load gave me better accuracy than any other, even better than H1000 would give me with lower velocity.
    Cheers.
    gun)
     
  10. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    Double based powders are very hard on throat area



    Military used the RL 22 with the MK 248 Mod 0 load prior to the Mod 1 with H1000.
     
    Last edited: Dec 5, 2013
  11. Nomosendero

    Nomosendero Well-Known Member

    Messages:
    1,079
    Joined:
    Jan 17, 2005
    Likely you are right, I recently bought some, won't hurt to try a few rounds in my Sendero to see
     
  12. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    fed 210 Match primers used in MK 248 Mod 1 loads not FC 215m (no crimp)
     
  13. diriel

    diriel Well-Known Member

    Messages:
    409
    Joined:
    Sep 22, 2010
    If you look around you should be able to get the actual PDF that tells literally everything there is to know about this round. The max working pressure allowed under variance of pressure is somewhere around 78kpsi ...77 or 78...pretty insane.
     
  14. alaska

    alaska Well-Known Member

    Messages:
    619
    Joined:
    Feb 1, 2010
    Really is too hot of a round 77.8 is the load
    I read somewhere production was halted on this round