You can remove the ong barrel from the Gamo P-25 Tactical although that will not make the barrel shorter.
As long as the pellet is .177 Cal then any .177 caliber pellet will work in your .177 Gamo.
some have larger blade screws( 6 inches long) inside the buttstock, remove the butt plate and it will be recessed inside, you need a long, large screwdriver.
the barrel is the long part that the bulliet comes out
the longer the barrel the further it shoots and is more accrurate
A 22 with a long barrel would probably be better because it should go straighter.
It might fit, but why would you want to do that. It has no gun powder and won't fire.
The Thompson Center hawken that I have,has a barrel that is 28 inches long.
It depends on the barrel.
Pull the bolt handle straight out. Remove the two screws holding the receiver cover and lift cover off. Mind the ejector which is loose stamped steel, held in by the cover. Remove screw holding the barrel to the stock and remove the barrel. Remove bolt to the front and clean. Reassemble in reverse order. Take care to replace the ejector.
580mm, or 22.83 inches. Rather long barrel for a .22 rifle.
A rifle
is that 1948 or 1848 ..............??? if 1848, barrel is about 8"