UGB25 question?

Anyone know if Beretta UGB25 is adjustable for shooting lighter loads? Currently have one that handles 7/8 oz. @ 1225 fps with no problem (trap model with 30" bbl.). Another only works with max load 7/8 @ 1400 fps (sporting model with 28" bbl.). With forend removed, I noticed a substantial coil spring around what would be the magazine tube in most 'normal' semi-autos. Haven't figured out why one works with the lighter loads, while the other doesn't. It's recoil operated, so no gas ports to alter. Found an owner's manual online, unfortunately, it's in Italian! TKS, Don P.

 

Mi dispiace, ma non so leggere l'italiano. Forse qualcun altro può aiutare.

That means " I can't read Italian. ...Maybe someone else can help."

Google Translate can do the translation, but you can only do a small portion of text (1000 characters) at a time.

 

i don't believe it is adjustable, i owned 2 of them in the past and I don't remember that ever being an option but mine would cycle anything and do it fast

 

One great gun, my gun will cycle every thing.