Model 70 Magnum to standard bolt face

Discussion in 'Gunsmithing' started by buckbrush, Dec 23, 2009.

  1. buckbrush

    buckbrush Well-Known Member

    Messages:
    282
    Joined:
    Nov 26, 2008
    Have a model 70 that was originally a 7 mag. It's a post-64 push feed. I really want to try a 260 Ackley but I don't know where to find a new bolt.

    Is there a way to modify the current bolt?

    Anywhere to find a new/used bolt?

    I noticed another guy found one in short order in the general forum. I've looked all over and can't find anything.

    Thanks.
     
  2. GNERGY

    GNERGY Guest


  3. NesikaChad

    NesikaChad Well-Known Member

    Messages:
    753
    Joined:
    Jan 28, 2007
    T slot extractors are the bugger in this deal. A guy will have to fill the hole and relocate it for the detent or a new extractor will have to be made with the right offset to reacquire the case rim.

    All of which is certainly possible, but it does drive up the cost.

    Personally, I'd go this route as it retains the original appearance of the rifle.


    My thoughts on alternatives:


    For a long time the Sako extractor upgrade was the only game in town for this type of stuff. There's been a trend lately that is slowly starting to move away from this. The reason being is the potential liability of this particular extractor design when installed in a Remington or Winchester push feed action

    The Sako extractor is not physically retained in the bolt by anything other than spring tension and clever mechanical interaction. There's no cross pin or slot to keep it in place. The risk in this is that (say for instance) a left handed shooter is using a right bolt/right port gun and experiences a case that "sneezes.' (ruptures) It is very, very realistic to expect that extractor to come buzzing out of the breech area and then decelerate into your face. An eye socket could be potentially fatal.

    If you look, the extractor is positioned roughly at about 1 o clock when the bolt is out of battery and running in the race ways. Rotate into battery and now it has a direct path out of the breech (3 o clock for a R/H action) because it's rotated to the raceway position. There's nothing supporting the outside of it to prevent it from coming out. Anyone who's experienced a violent case rupture will tell you that stuff goes flying everywhere when physics takes over and all that pressure goes with the path of least resistance.

    I've installed many, many of these and I've never personally experienced this, but I do hear stories from time to time that suggest that it does happen.

    I personally really like the miniature M-16 extractors because it has positive mechanical retention in the form of a cross pin. A bolt equipped with this and thoughtfully drilled gas checks reduce the potential risk.

    Just something to think about.


    Merry Christmas all.

    Chad