The action of Mauser Rifless has stood the test of time. It has proven
that it is one of the most Safe, reliable and accurate firearms
ever built. Although to achieve a precision rifle and to greatly
improve on the mausers accuracy the action can be trued. Which consists
of squaring the Receiver face, lapping the bolt lugs and lapping
the bolt face. The lapping can be done at home with the proper tools
and knowledge, however Squaring the Receiver face needs to be left
to a skilled gunsmith with a metal lathe.
Lug Lapping - The Mauser bolt lugs locks in the receiver when closing
. The amount of metal that makes contact between the bolt lugs and
receiver is where lug lapping comes in . Lapping the lugs provides
more metal to contact the lugs and receiver and improves the squareness
of the mating of those surfaces. It is accomplished with a lug lapping
tool which can be made or bought and it is available from Brownell's, Midway or your favorite
gunsmith supply store. It works by threading the lapping tool into
the receiver [ the barrel threads ] and applying lapping compound [ or vallve grinding compound ]
to the lugs of the bolt and rapidly opening and closing the bolt.
This increases metal to metal contact and when finished assures the lugs are both
firmly against the receiver when the bolt is closed. you will be able to tell how much contact is being made by the nice shiney spots on the lugs . I like to have around 70 to 80 percent contact area. you can over do this and possibly lap to much i wouldnt suggest going for more than 70 percent .
Bolt Face Lapping - The face of the bolt is where the head of the
cartridge makes contact with the bolt. By lapping and squaring this
surface it insures that the cartridge is in full contact and stress
free and in-line with the chamber of your barrel. This is performed
with a bolt face lapping tool also sold by Brownells or Midway [ and can be made as well ]. By inserting the
bolt face lapping tool into the threads of the receiver with the
bolt closed and applying compound to the face of the bolt, use a hand
held drill which rotates the tool and squares the face of the bolt improving
accuracy greatly. again you can over do this go slow.
Squaring the Receiver Face - The receiver face is the metal that
comes in contact with the shoulder of the barrel [ which is the
surface the barrel mates with allowing the barrel to be tightened].
Squaring this surface insures when the barrel tightens up it is
100 percent squared and inline with the receiver. This is accomplished
by putting the receiver on a mandrel and using a metal lathe, remove as little as possible of
metal to insure the face is squared. As stated above this is best
left to a competent gunsmith even if you have a lathe as the smith
will know the tolerances of the metal and not damage the heat treated
[ hardened ] surface.