Un numbered Hold Open
 

Hi I am looking at a 1937 s/42 with matching numbers except the hold open. How much does that affect the price. Everything else is nice.

Any non matching part hurts value a lot - to me, certain things don't hurt as bad, firing pin, hold open, grips

But to others they would simply not want it

But, everything depends on condition and price IMO

Hard to put a number on it because of all the other variables, condition, rarity of the gun, who is looking at it, etc.
If I had to ballpark it, I'd say that a 10% discount is in order, but that could go 10% either way. On a low end gun or a shooter, it means nothing, but on a minty piece at top dollar, it's going to hurt a lot more.
Let's see what others say.
dju