They started with 101,as has been stated earlier..
Now the very early pups had no R prefix on the serial #,also early ones stated Rohrbaugh R 9 s
On the right side..
These were Farmingdale marked,with blue CF grips..
I was told by Karl Rohrbaugh that 300 of the blue sets were made..
There were 46-47 of the "early grey anodized" models made-these would not have an R prefix..
When exactly they started the R prefix,I do not know exactly-but it had something to do with the dropping of the s on the side, I believe that the BATFE had a ruling on..
To be able to say at such and such a date,this is when this happened,per serial #-won't work..
RiffRaff had it right about not being sequential..
Consider Farmingdale manufacture "early" and Deer Park "newer" I guess..
I sure do like the old CF blue grips!!
3 different "flavor" frames also...