The only real argument the seller would have for increasing the price is that this gun has all matching parts. You state that all the parts are matching...except the magazine. OK There is only one magazine? Would be nice if there were two. (another point you could mention- especially if you want to shoot it)
Even if all parts ARE matching, refinishing and pitting would still be a strong argument for you to keep the price down. Serious collectors are very fussy when it comes to the condition and appearance of the gun. Even a little rust or pitting turns many collectors away. Also, while rust can be removed, removal of pitting is far more difficult. Even one mismatched part will cut the gun's value by 30 - 50%
Hope this helps
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