Hi Dee,
Firstly, i'm afraid you can't really show them loading the gun in that position as it would never have happened, therefore i'd suggest showing them preparing to load once the shot has finished firing. Alternatively you could remove the barrel and attach it in the normal position.
When building my Pak 40 I did loads of searching on the internet and found no pics of a gun actually in recoil. However, there is a video (
here ) on you tube which includes some renactors firing a Pak 40 that should give you some idea of how the crew behaved during firing.
Please note though that these are renactors and they aren't firing real shells and are not being shot at and so it is'nt 100% accurate but probably as good as we can get these days!
Hope this helps,
James