It all depends on what league you shoot bell target in, some such as South Wales and Newport have much tighter scoring due to the fact that most of the competitors use at the very least a FWB300 and there are many modern PCP's. In such a league you would be very hard pushed to get anywhere with a break barrel springer such as a HW30 without at least having dioptre sights.
I shot for years in Swindon league, the competition is shot on paper derived from the original Birmingham/Black Country bell target but scored differently, I used an Original Mod 75 for regular matches against the modern rifles but every year we had competitions for specific rifles such as the FWB300, Original Mod 50, BSA Airsporter/Webley Mk3, and pre WW2 BSA underlevers, all these were conducted to keep alive the "milestone" guns used in in bell target leagues countrywide.
Swindon League shoot 6 targets, scored to 10 so a perfect or "possible" score is 60 on a card which must be shot in 5 minutes, you are allowed a "sighter" shot on a non-scoring ring on the target but this is included in your 5 mins, so the pressure is on for any gun that is slow to load. As far as difficulty goes it's difficult to shoot regular 60's with even the most modern PCP's.