I would think the majority of Baker 12ga would be either 2 5/8" or 2 3/4". Other lengths could likely have been had on order as for most American makes of guns, but these were the "Standards".
I cannot recall having ever seen an American made 12 gauge with 2˝" chambers. According to Greener even British so called 2˝" guns had chambers which actually measured from 2 9/16" to 2 5/8". My Birmingham proofed J P Clabrough measures 2 5/8".
Most early American doubles in 16 gauge had 2 9/16" chambers with 20's having 2˝" but for 12's it was generally 2 5/8" with several makers going to 2 3/4" early on.
