The older single six's are sweet guns but hardly rare. Especially in 80% condition, w cracked grips, and missing the second cylinder. Based on my experience in owning a good 1/2 dozen of these over the years, I'd say $300 would be a fair price. Certainly no more than $350. Now if the gun were clean and complete, it would go north of $450-$500 with ease.

That said, if you're buying to help out the family and/or to have a keep sake, then you need to figure whats right for you.

p.s. It's always a god idea to look at the big gun auction sites closed auctions to check the value for yourself.

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Dave