I think they are very similar in size the Walther LG 55 and I think the both take the same spring. If so the experience I have had with my two LG 55 is they are lovely to shoot at 6ft fb and below, but are horrible when you try to increase power. One of the most comfortable and pleasant spring rifles to shoot, having a short compression chamber so the weight and balance is so comfortable at the shoulder, easy and smooth to cock. Normally rifle barrels are bent upwards from accidental firing when barrel is released when not in battery, (the LG55 has a safety mechanism to stop this) so yours must have a huge spring in to bend it down when cocking !
Baz