I just got an AA USPc.45 SS, my 4th USP. It's practically new, showing almost no signs of ever having been fired; and the price was very good. However, I'm a strictly V1 man, and the new addition is V3 [decocker only]. What would be needed to change from V3 to V1? Is it something my all-thumbs brain could doon its own, or should my LGS do it instead? TIA.