Revolver Modification

[Carver Knife]

I've read and heard conflicting information on the modification of revolvers.  Specifically, installing a hammer with a lower spur.  What is the source of the "real rules" on this topic?

[Jackalope]

The current (Feb 2016) Shooter's Handbook, page 3, under SASS Firearms Covenants:

"HAMMERS

Hammers may be replaced or exchanged with hammers designed for the same frame size (e.g., small frame revolver hammers may not be installed on large frame revolvers or vice versa).

Internal parts of the hammer may be changed (e.g., to allow for a half-cock notch on a revolver).

Ruger Super Blackhawk/Montado style revolver hammers (i.e. lowered and widened hammers) are acceptable on both adjustable and fixed sight model revolvers.

Hammer stops may be added. The hammer travel distance on any revolver may be adjusted.

Rear sight notches cut into the revolver hammer may be widened.

Hammer spur grooves may be recut."

Apparently, the option of modifying hammers applies to other makes and brands as well.

[Carver Knife]

Thank you.