Discrepancy with old Mizuno irons (MS-3)

[RoyJeeBiv]

Hello all,

I received some hand-me-down clubs from my dad, some older Mizuno MS-3 irons.  I'm anxious to try them out, though I noticed a discrepancy when looking online for some info on these clubs.

Here is a picture of the irons I have -- note the curve along the backside:

But of the few other places online that had photos of these irons (save for one), the clubs are straight along the back with no curve (this particular source has the 'authorized by' stamp on it, but others don't):

Does anyone have any insight for this; perhaps just different years of manufacture...??  I find it interesting that the same model number would have such a big difference (I guess more MB vs blade-look...??).  Thanks in advance.

rjb

[GaijinGolfer]

I believe the bottom one is the, "reverse muscle" that they made a year or 2 into the MS-3's run.

[RoyJeeBiv]

Excellent, good to know -- thank you!!