Hi folks... Im looking for any information you guys may have on a rifle Ill be picking up on Sunday

So far from the serial TB4134 Ive found out it was produced March 1987.
It looks to have walnut stock, adjustable buttplate, and fixed scope mounts, the safety is the (anti bear trap?) pulldown model in front of the trigger which I believe makes this a sirocco classic?
Condition from pics and description is cosmetically 5/10..pitting, wear to bluing, dings and dents on stock, but Im assured it fires and is very accurate - it is a .22 - Im paying £100 for this with a gunslip and an unidentified scope... I reckon this is a pretty good price.

On another thread someone mentioned that post TB4000 models are HE Gas rams - can anyone confirm this?

At this stage I normally search for exploded diagrams, user manuals, parts lists, any kind of instructabkes, stripdown guides etc.. and stick them all in a folder - but Im turning up nowt.. Ive emailed Theoben USA in the hope they have records of some kind, but Im not holding out...

any help would be much appreciated.. thanks