Here goes,
Handguns:
S&W top break in .38S&W, nickle plated, first issued handgun.
Colt PP .38 Colt.
Colt Bankers Spl (RB/SB) .38 Colt.
Colt PP .22 Target, per R.L. Wilson's Colt book
Colt PP .38 Spl.
Colt Officers Model Target .22LR-Shooting Team weapon
Colt Officers Model Target .38 Spl-Shooting Team weapon
Colt Detective Spl .38 Spl.
Colt Cobra .38 Spl.
Colt OP .38 Spl (4 inch/2 inch and possibly some .22 LR trainers).
Colt Commando .38 Spl.
Colt New Service .38 Spl., per RL. Wilson
Colt .25 (unk if 1908 or Junior).
Colt Woodsman .22, 6 guns made for BPD in 1938, serial MT3339 to MT3344. per Colt Historian
S&W M&P Model of 1905 4th Change S&W Special.
S&W Victory Model 4 inch .38 Spl.
S&W M&P pre-Model 10 2 inch .38 Spl
S&W Model 10 2 inch, SB, .38 Spl
S&W Model 10 4 inch pencil barrel, SB, .38 Spl
S&W Model 10 4 inch HB, SB, .38 Spl
S&W Model 64 4 inch, SB/3 inch, RB, .38 Spl
S&W Model 45 .22Lr.
S&W Model 36 RB/SB 2 inch .38 Spl.
S&W Model 37 RB/SB 2 inch .38 Spl.
S&W Model 60 RB, 2 inch .38 Spl.
S&W Model 38 RB .38 Spl (Just saw a pic of a late 60s, early 70s Policewoman with one).
S&W Model 649 .38 Spl.
S&W Model 659 9MM (12 for our entry team in the late 80s).
S&W Bodyguard .380 (for UC, 2014-2019)
Walther PPK blued and SS .380 (UC guns).
Beretta .380 (UC guns and unk model).
Ruger Speed Six SS 4 inch and 2 3/4 and a small number of 2 3/4 DAO in .38 Spl.
Glock 19 9MM. Half marked "BOSTON PD" on the slide, the other half unmarked.
Glock 22/23/27 .40 S&W. These are current issue, the transition to G22 gen4s and eventually G27 gen4s (detectives) has begun. The G23s and G27s are marked with B.P.D. on the slide. The 3rd gen guns will be destroyed, per City of Boston policy.
Glock 22 gen4, .40 S&W. Current issue.
Glock 23, Gen4, 40 S&W, for plainclothes. Current issue.
Glock 43 (UC gun, 2019-present)
Sig 1911s for SWAT issue, replaced as needed with S&W 1911s.
Glock 27 gen4 (shipped to Dept, never issued, sent back)
Sig 320 9mm (unk model) for SWAT. Current issue.
Also, Colt New Services in .38 Spl were reported as BPD issue in "The Book of Colt Firearms Third Edition" by R.L. Wilson. Nickle finish seems to have be used in early Colts as well as the top-break S&Ws. All revolvers seemed to be BPD marked, with the exception of some of the Model 649s and maybe the Model 60s. Other handguns may have been issued that I've never seen or heard of, Undercover guns, etc.
Long guns,
Bolt Action (Krags, 1917s or Springfield 03s) from the WW1 and post-WW1 period, Red Scare, etc., WW2 Civil Defense.
Maxim machine gun (or a Colt-it's seen in older photos from the Police Strike).
Thompson Submachineguns, legend in the dept, it's believed 6 were in stock.
M-1 carbines (back in the 60s during the riots, unk if issued or taken from Gov't stocks).
Winchester Model 12
Remington 870s, full and folding metal stocks.
Smith and Wesson 3000 riot gun
Ruger Mini-14s (select auto AC556s).
Colt M16A1
Colt M4s, 2 per district and carried in gun cars, small number of Bushmaster M4gerys and S&W M&P15s for SWAT Team and Range staff.
Benelli semi-auto shotguns in 12 gauge for SWAT.
Unk bolt action rifle in .308 for SWAT.
200 surplus USAF M16s (converted to semi-auto only) in locked metal containers somewhere.