This is a book of ways in which a great gunsmith could modify the guns that they create and use. Useful information, no doubt.
Tinkering Pattern: Sawn Barrel
This pattern shows the techniques involved in sawing off the barrel of a shotgun - in the process, you lose accuracy but gain in damage. Not having a barrel also makes it weigh a fair bit less.
It looks like the basic application of this would be of quite low quality.
You would need to tinker with an object to apply this pattern.
This pattern requires the following non-consumeables:
saw: At least quite bad quality
Dunglen University Library