Rather than punching more adjustment holes, I took a more laborious route and physically
shortened the strap on my Filson bag. It turned out really well...
It is quite simple if you have the tools and a brass "Chicago screw," which essentially is a rivot that is held with a screw rather than permanently pressed in with a tool. You can get them on eBay.
1) Cut the strap piece shown in the pic to the estimated length desired. I cut off around 5 inches from the end that attaches to the bag (again see pic). I used a razor blade to make a clean cut and a black Sharpie to recolor the cut end.
2) Drill two holes using a conventional drill and bit. I used a drill bit which was slightly smaller in diameter than the Chicago screw. I then used a Dremel tool to enlarge the holes until the screw just fits through.
3) Fold the strap end over and secured it with a Chicago screw. I used epoxy inside the screw to make sure it never comes unscrewed.
The result is a shorter strap that doesn't have a foot of "excess" strap flapping around as you would have if you just poked more adjustment holes. Just looks cleaner and looks almost completely stock, IMO. I was even anal enough to repeat the process on the other end just for visual symmetry.
I guess I could have punched more adjustment holes and simply just cut off the excess strap. However, I think it will be hard to replicate the original rounded end.
Anyways, just an alternative way to shorten the strap for those brave enough to try, have the necessary tools, and don't ever plan on reselling their bag.
I just love my 232 medium field bag. It is the perfect bag for me. Here is a pic (before the strap shortening, showing all the excess strap)...