Midway and Brownell's sell a barrel that will convert a 10/22 magnum to 17 HMR..... I'm unsure whether it just is a simple barrel swap or if more parts are needed like converting a 10/22 to .17 MachII. I don't know how accurate they are tho.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).