GP 100/ GP161 What is the difference ?

Scratching my head.

The GP-100 is the revolver model in all of it's variations. The GP-161 is a specific variation of the GP-100 revolver having a 6" barrel and in blue steel. The 4" blued versions, 4": and 6 inch stainless steel versions, etc. have specific model numbers but are all are GP-100's.

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