Originally Posted by kcwheel

Here are some dimensions taken from Triple Lock SN 09. It is a pre-production item made for the army trials. It has a 6 1/2 inch barrel with no caliber markings. This gun was part of my brother's collection.

Headspace in gun: .055 (cylinder pressed forward)
Cylinder OD: 1.694
Cylinder length: 1.580 (1917 cylinder is 1.535
chamber depth: .895
Chamber dia: .477
Throat dia of cyl: .454
The front of the chamber is tapered like any other rimmed cartridge chamber.

I will try to attach some pictures. The third round has no headstamp, all others have the FA 4 06.

Ken