Curl:
I doubt that rifle will give you any headache at all!
What a fine example! Full accessories numbered to the gun, wow!

Did it come with any info from the maker's register? Loading it should be a snap.

AKMike: safeties in that position are not uncommon on best-grade hammer-guns of the period, particularly those by AH. The 20/.577 I shoot occasionally has identical locks in every respect.

One wonders why Alex Henry fitted safety-bolts to rebounding locks in the first place.

...because he can!