My impression is that as simple as Scott Gas Check Pat 617 is, it is one of the most effective. One would assume it was used pretty universally after it came out. But, I can't find a single extant Reilly in my database with the patent listed on the gun. That doesn't mean it isn't there....just that it was not listed.
I do have 3 guns with Scott Patent 761 of 1878 with patent use numbers on them which I'll make a graph of...and 5 guns with crystal indicators (but without use numbers or patent stamp that I can see - perhaps this is stamped on the plates?). Anyway, use numbers are one of those little important bits of data that gun sellers mostly omit.
I'll check my own 16 ga (1886) to see about Pat. 617. My 12 bore is 1898 and the patent would have expired.
