Help identifying shaft specs?

Hi all. I originally posted this in the equipment forum but it sank without a trace, so I'm hoping for better luck here. I am currently playing a set of JL MM prototype irons and I love them. Hit them better than the hundreds of newer irons I've tried and I think it's down to the shaft weight. Now, as a WRX'er I'll probably buy another set of irons in about a week or so, so when I do I'd like to try to find something with a similar shaft. Problem is I can't find any info on these shafts. They are Rifle Precision 100 in S flex, but unlike other Rifle shafts, they don't have a number designation like 6.0 or whatever. Any one got any idea?

i dont know that model, it was off the marked before my time, but "S" flex is FCM 5.5

( 5.0 = Firm or R+ / 5.5 is S / 6.0 is S+ / 6.5 is X)

My theory is that this is a regular FCM shaft, but sold trough OEMs with classic flex labels (L.A.R.S.X system), but its confusing that the labels is BLUE, thats True Temper, i have not seen Brunswick / Royal Precision with blue labels, so i really dont know what it is, but since the text say Frequency matched and the label is "S", then its FCM 5.5 for flex.

Check total wgt difference from #3 to #9, that will tell if this is Constant wgt (they made a few models), or if its Descending (most likely). Constant wgt will be 7 grams average, from club to club, Descending closer to 6 between clubs.

Lets hope someone who worked with Rifle shafts more than 10 years back in time chimes in to tell us what this actually is.

If nobody can help out, send a mail to KBS and ask for help from Kim Braley, he was the designer of Project X shaft, and its his father who was behind the company Royal Precision, so im convinced he know what animal this is.

Try to look into Golfworks databases for shaft change, you might be lucky to find it there if it was delivered as a standard option from the club head manufacturer.

Im in Europe and we are blocked from using many US webpages, Golfworks is one of them, so i cant do it for you.

Thanks folks, your efforts are much appreciated.