Originally Posted by Chukarman
Dickson made a few 'side opening' O/U guns. I believe that D Mackey Brown's O/U is an easy opener (assisted opening) gun. A true Self Opener springs open whether the locks are cocked or not. Purdey and Henry Atkin come to mind.

Also, Lancaster offered a Spring Open boxlock not patterned on the ANSON & DEELY action. Pretty cool, but I have never seen a 'best' version of the gun... always 'colonial' models.

The Beesley designed self opener action used by Lancaster is a true self opener and the action could be had in both sidelock and body action models. I own 2. Both top quality, the sidelock being “Best grade”. Lancaster called this the Model A.
The body action gun I own is not colonial grade, it’s the nicest grade that Lancaster made in that action. It only cost a few pounds less than the sidelock model in 1896.

Body action circa 1896
[Linked Image from i.ibb.co]

Sidelock circa 1894
[Linked Image from i.ibb.co]