610 Or 613 How To Know The Differences

Hello all, the perforation is 11 but how to know if it rotary or flat? TIA

what I've learned
Check the back for offset
Look around the outer frame of the image for discolouration (the rolls where cleaned as best as could but transfer happened)
If you haven't ruled it out yet
measure the image frame line to frame line
Rotary pressed stamps stretched during printing
So the flat plate is smaller 21mm I think don't quote me vs rotary 22.5mm I believe
There was a great post on here about this
Hope this helps
Here is the thread-
https://www.stampcommunity.org/topi...PIC_ID=51695

Building on just_fella's post, both of your stamps show minor black set-off on the back side from the stacking of the sheets from the flat plate printing process. Also the right stamp has a natural straight edge and guide line at the right side, which can come only from the flat plate stamps.

The top straight edge on the left stamp could be natural or from trimming. The set-off proves it is flat plate, and the right stamp can be used to compare the height/width against this left stamp. It is better to use stamps of known flat or rotary production methods than to use a ruler, which often gives very poor resolution.

As an aside, the right stamp has a partial territorial parcel post box cancel from Arroyo, Porto Rico.

More information is here, note this section "Do I have a Rotary Sheet Rarity?"
https://stampsmarter.org/1847usa/ByYear/1923.html
Don

Thank you all very much

For anyone hunting for a 613 stamp, get a copy of a 612 stamp and a copy of a 610 stamp for reference comparisons. The 613 stamp has the frame dimensions of a 612 stamp and the perforation gauge of a 610 stamp. Here is an interesting reference: https://goscf.com/t/69255