Recently Discovered US Scott 517c

Just received a cert for a stamp I submitted to the Philatelic Foundation late last year. Found this stamp among a collection I purchased more than five years ago and had only recently gotten around to working on it. If I'm not mistaken it is only the fourth 517c to receive a cert and only the second 517c with transitional perfs. Can hardly believe I found this needle in a haystack. Hope you all can understand my excitement.

Wow! Just wow! Congratulations on your discovery.

I guess you did not mind the certificate fees.

Great find! One's willingness to check for the unusual can and at times does pay off. Great eye.

that's a pretty exciting find. very nice.

Wow, what a find! Congratulations. The odds of finding this are truly amazing and at least another one is being preserved. It should go into the Siegel census.

Excellent!

Well done and thank you for sharing.

Absolutely!
How does one tell that the Pmk is a "registry"?
What are "transitional perfs"?
Congratulations.

Super find with double oval registry cancel and perfs on top starting off 10 perf transitioning to 11 perf. Amazing! You rock!

Very impressive that you found a stamp that could be so easily overlooked.

Wow - what a great find.
So how many of us are now checking/rechecking inventory and albums?

rod222, the letters inside the inner oval are REG.

After checking a 1,000 stamps it doesn't seem worthwhile to check a 1001. Many collectors have handled this prize, without realizing what it was. I bought kiloware years ago and assumed that there was nothing of real value in there. Probably, likely correct.
Having said that, Mr. Gettinold is a real COLLECTOR to "discover" a prize that has been waiting to be discovered for a 104 years. I salute you!

Thank you all for your comments. In answer to your question Rod this explanation was found on an auction website:

At a certain point during production one of the perforating wheels became defective. In the course of repairs part of one perforation wheel was inadvertently changed from Perf 11 to Perf 10. Based on the physical evidence of surviving copies, this was the nineteenth row of pins on the wheel.

I had to celebrate last night. Today my liver hurts.

After checking 1000 stamps the odds improve when checking number 1001, the next stamp. Your lowest odds of finding the needle in the haystack, well, rarity in the kiloware, is the first stamp you check. If you were willing to check the first stamp, checking 1001 should be a no-brainer.

GMC89 - you just never know. Last year I bought a lot from a seasoned collector that had hundreds of duplicate Canadian stamps. I sat there and looked at a whole pile of 10c 1935 Mountie stamps with a magnifying glass. They are Scotts 223 and there are a few varieties to look for. Before I went cross-eyed I did spot one very nice 223iv, which has a little loop on the horse's back. The cat value is $375 CDN which isn't life changing, but I set out to find something and there it was. I sent him a picture right away and he was a good sport. This could have also gone undetected for 90 years. He was glad I found it and I'm glad it was practically free.