Never heard of any Diana in .25. (or .20 for that matter). Dont know whether its original. But a dealer must be able to check that for you.
Ive had several 54s. Mine had T05s. Dont like the T01 triggers at all.
Im not really into sidecocking either. The sidelever makes it a tad off-balance too.
Yes shooting is....weird. Really recoilless. Bút because of that, boring as well
Theyre easy to shoot. But kill as many scopes as any other magnum.
Last one I had was a laminate. Quite rare. But it had cocking problems from new and I lost my temper with it and sold it.
The TX SR is very nice too, but I/we, can say everything (negative) about the 54, its the ONLY one of those 2 still in production.
If I had to choose, Id choose the 54. With the T06 it has a better trigger. And of course it would be new.
Id try in .25 especially JSB. As second Baracuda match. Third FTT.
I only have 1 airgun preferring baracuda (a patriot), no airgun that prefers FTT and a lót that prefer JSB