Need Help Re Ashton Potter Vs. Sennett Security Products?

How do I tell the difference? I know this is a sophomoric question to the veterans on here, and I tried doing a google search before asking, but I can't find anything on the internet or on Mystic Stamp, Kenmore stamps, or Stampworld that tells me. So, I am appealing to the geniuses here.

Help?

*** Moved by Staff to a more appropriate forum. ***

There os no simple answer that covers every design that was printed by both printers.

However, for coil stamps that were issued on rolls of 100 the vertical die cut pattern is different. The very top and bottom of the pattern on Ashton Potter stamps is perfectly vertical, while Sennett ones it is sloped.

As eyeonwall has noted, you can distinguish between APU & SSP (now BCA) coils by examining the die-cuts as he indicated. You can also take a quick look at the die-cut gauge used on the coils, as it is considerably different ... usually 9.5 for APU and 11 for SSP. In other words, there are more teeth along the side of an SSP/BCA coil.
For booklets, the die-cut gauges are usually identical, making a definite id more difficult. While there is no general rule that I know of, there are always minor differences. Included among these are location of microprint, date differences, design sizes, etc. E.g., for the 2018 flags, the APU dates were darker/heavier than their BCA counterparts. For 2019 flags, it is the BCA flags that have a heavier/darker date. Since these differences are usually on both the coils & the booklets, you could always first identify the coils via the die-cuts ... and then compare design details on the coils to the booklet stamps. But be forewarned ... occasionally one of the print vendors will muddy this comparison. On the 2018 flags, APU used different locations for the microprinted USPS on their coils & booklets. But since neither location was that used by BCA, one could still use this detail as an identifying characteristic.

Thank you, eyeonwall and JLLebbert. Very helpful.

I do not recall a single issue where one could not determine SSP or AP by some characteristic that only needed at most a perf guage or a magnifier. The perfs are almost always different. Microprinting helps on some issues.

Brookman's online price file (what ends up in printed book)is very good a noting the distinguishing differences if one wanted an online method.

If you are looking at plate blocks or booklet panes, the letter which begins the plate number will identify the printer.

S - Sennett Security Products (and sometimes Banknote Corp when printing for Sennett Security Products)
B - Banknote Corp.
C - CCL
P - Ashton Potter

As others noted, the die cutting/perforations are unique to each company's printings. Scott Specialized catalog would be a major source of information on this.

Very helpful information. Thanks.