My Latest Project

We at the 25th SOG are starting to get some weapons made,
  The first one that I am working on is the M3 Grease gun.

First things first, the parts that you need are, 1) 14 inches of 11/4" pvc pipe (that you can find at hardware stores, plumbing, or electrical supply houses). a 11/4" to 1" reducer, (get the one that is designed for plumbing, it looks Much better! A 1" to 1/2" reducer (again get the one designed for plumbing). A 11/4" end cap (you would  find that in the plumbing section to). the top photo on the right is of the center housing of the Grease gun (which is made by cutting the correct shape on the band saw) you would use a 2"x4" or a larger piece of wood.
The next photo down on the list to the right is of the fittings
that were described earlier in this post.
the lowest photo on the right is of the barrel assembly, it incorporates the fittings, and includes the barrel (a 1/2" piece of pvc pipe 8 inches long). (the barrel is not cut in the photo).
 If you want to make one I would deffinatly suggest that you go to Wikipedia and look at the article on the M3 Grease gun
Its the best way to get a knowledge of the gun.
and you could do a Google search on the M3 grease gun,
In images, there are a lot of good pictures of that gun.