If you had that gun or pair of guns 10k would be a steal. But to fit them to another, a third and fourth gun is a stretch. If you could track down the gun they were fit to I can see this as a great buy. Just for the rest of the guns that they might fit it is a gamble, 10k with no returns. I've tried this before, not for this much money, and ended up either giving up or getting into a money pit.
If returnable and I had a pair they might fit, I'd roll the dice but with no chance to return them I would not be inclined to take that gamble. It is all risk/reward and while the reward is high the risk and marginal chance for a fit without any chance to just return them and get my money back makes me want to pass. I'd rather drop ten grand on something else and I am not a big fan of 27", 26" or 25" barrels anyways. If they were 30 or better yet 32" barrels my whole attitude would be different.
