Diana Model-10 - First Pattern.
This precision recoilless break barrel pistol was made from 1975 to about 1990. (Source: John Griffiths, Encyclopedia of Spring Pistols 2008)
This example comes in its original case, which is lined with very 1970s-style orange foam rubber and covered with brown vinyl.
It is a first pattern mod 10 and the serial number shows it to be one of the earliest of these pistols ever made. The model 10 has a plastic barrel shroud/cocking aid which rotates 180 degrees to protect your palm from the front sight digging into it when cocking.
This example has a fixed rear sight and an eccentric sleeve adjustable to bear down on the web of the hand for extra stability. The second pattern mod 10 lacked this sleeve, had a rear sight that could be fixed in three positions and a lead weight fixed beneath the barrel shroud.
The barrel weight fixing bolts were drilled through the plastic shroud and created a weakness, so the second model is sometimes encountered with cracks in the shroud at this point.
Note the matt black phosphate finish.
Note the various ways in which the walnut anatomical match grips are adjustable.
Note also the front sight, which has a rotating element which alters the visible width of the post. Quite a few of these pistols turn up with this rotating element missing, but the fixed metal post behind it works perfectly well on its own.
Diana's opposing piston recoil cancellation system ensures that the pistol feels dead to shoot. Its long, low sight base make it feel very pointable, like an extension of your hand. It's quite stiff to cock. The trigger is magnificent.
Diana Model-10 - Second Pattern.
This version of the mod 10, introduced in January 1977, had a detachable lead weight under the barrel shroud/cocking aid. The rear sight could be moved along the cylinder and lock in three positions. The sight locking bolts screwed into lugs brazed onto the top of the cylinder.
Diana mod 10 cutaway
See also this Crosman Medalist 1322/1377 cutaway
See also this Webey Senior cutaway.
See also this cutaway Diana LP6.
See also this cutaway Diana 75.
See also this article on a cutaway Original model 27.
See also this post of three cutaway models