B. M. Chamberlain spoons

[AllSeasons]

OK, I couldn't help myself and bought more coin silver. These spoons are marked "B. M. Chamberlain" and "Salem". I believe they are attributed to Benjamin Mooers Chamberlain, who's registered as a jeweler in Salem, MA. I believe some of his brochures at the time also refer to silverware and silversmith. However, since he was in a partnership with John Ford Smith, his most common mark seems to be "Smith & Chamberlain". Perhaps these were retailed before 1840 (age 22) or after 1870 (age 52)?

A few questions I was hoping to get some insight on:

• The customary question of is it indeed coin silver?
• Is it attributable to Benjamin Mooers Chamberlain? If so, what would be the approximate time period?
• I assume Chamberlain was the retailer. Any idea who the silversmith may have been?

The images are below. Thank you in advance, as always.

[wev]

1. More likely than not.
2. Yes. With Benjamin Hazen Chamberlain as B. M. Chamberlain & Son, jewelers at 209 Essex Street, 1870-1880. His other two sons were also jewelers.
3. Impossible to know

[AllSeasons]

Thank you! Based on this, should I be concerned that these may not be coin silver? These are big at 9.25 inches long and 70 grams each.