17hm2 model # question

I'm looking at gunbroker to purchase a Mark II in 17hm2. I see a model F and FV with about a 16.00 difference in price. I assume the FV has the heavy barrel but why does F show a capacity as 10 +1 where the FV is 5 (+1)?

Does the heavy barrel use a different mag? ???

They come with different sized magazines. Don't know why, just the way it is.

They use the same mag, and can be purchased separately. They have both 5 and 10 rounds magazines.

Thanks for the info. I have a 17hmr now and love it. Thought the prices for the mach2 seemed reasonable.