I am putting together an AR-15 and an LR-260 simultaneously. I accidentally bought carbine buffers and buffer springs for both. My DPMS 260 has a rifle-length buffer tube and a PRS stock. I believe that I now need a full-length buffer; is this correct? Anybody have suggestions for a 24" target rifle being done on the cheap? Also, anybody want to trade for a carbine set-up? Or, know anyone that does?