One Stop Oak Framing Shop in Wiltshire
The M79 Sledge Head is equivalent to a 2 lb sledge hammer and is another interchangeable head that fits both the M1 and M4 handles.
Spanner to change head is available here
Atlas 46 AIMS™ Hammer Hold
Dead on Tools 22oz. Milled Face Steel Hammer
Dead on Tools 22oz. Smooth Face Steel Hammer
Estwing Ultra Framing Hammer Leather Milled 540g (19oz)