Can't the airsoft function be retained if the barrel is corrected to scale length? I thought this had been done before by using a pipe cutter to only cut through the plastic, adding a section of plastic tubing for the barrel sleeve and gluing the piece in (with sanding and putty to blend the seams in). The newly extended barrel would have a short section near the muzzle where the BB is not supported by the actual barrel.

I figured this would not hamper the shooting and the BB should make it out of the barrel just fine.... (?)

Are there other considerations that might inhibit the airsoft gun?