50-100 USD
27p
The value of a J Manton and Co double barrel 12 gauge shotgun depends on a couple things. Some of which, would be the age and condition of the shotgun.
Hammerless
If you're lucky about £400.00
about $3500
Try gun shows, want ads, gun shops, google.
The Model 1878 was offered in 10 and 12 gauge from 1878 through 1889.
I Just picked one up, I can't wait to find out were they were made? It's vicer nicely made gun, Good mechanics, as they say
What is the value of a Beebe arms double barrel shotgun?
when did the make the smithsonian double barrel shotgun
Wesson Fire Arms did. Values can range from 500-10000 USD dependig on EXACTLY what you have and how it is marked along with condition.
No reference lists J Manton.