If you mean "adjustable" by turning screws or something like that, no. But a gunsmith can work over that trigger pull the same way as any other trigger/sear/hammer combination. I would not recommend a DIY job, though.
Before you do anything, though, try pulling out the trigger group and doing a thorough cleaning job by washing it out in Kroil or (dare I say it?) gasoline, then dry and apply good gun oil to the pivot points and moly grease to the sear and hammer. You might find the result acceptable.
Also, try just working the gun a bit. If it was not used a lot, a little wearing in could also help a lot.
Jim