I carry a Sig P220 in 45acp.  Most carry a Glock in 9mm or 40S&W.  I just cant bring myself to carry a mousegun anymore and the Sig was a compromise.  I'd rather carry my M1911 but it's relegated to off duty status and not authorized for duty carry because it's a single action.  

Beretta 92 in 9mm though we are in process of switching to the Couger in .45
no back ups allowed, off duty anything you want   (mine is either my Kimber or Glock 23)
Rem 870 in the car.

What state/city are you in? I have the Cougar 8000(9mm) and I love it. wish I could carry it everyday though (I cant becuase im not LE yet!)

Glock 22 or 23 dept. issue with 180 Ranger SXT
Sig P232 to Admin. Narc. and Major Crimes.
Rem. 870 issued if wanted
SWAT has about a dozen MP5's, 2 Benelli M1 Super 90 14" entry guns, 3 M16A2's, 2 AC556, 4 tuned Rem 700's, 2 Sage guns for LL.
Personally owned AR15 or Mini 14's allowed after class and qualification. Backup's, .38 or larger up to .40. Must qualify and meet inspection standards, most use Glock 27 or S&W 642.

1)Springfield  1911A1 TRP/ 45ACP
2)Wilson Sentinel 45ACP/ Off Duty
3)Scattergun 1187 12ga/ Bushmaster Patrolman's Carbine/ Trunk Guns.

My PD issues the H&K USP .45 for general patrol with limited issue of the USP .45 Compact to Admin/CID.  No other makes/calibres are authorized.

Backup & off-duty is only restricted in that it has to be .380 or greater, within reason, and a quality brand as approved by our armorer.  I currently carry my Glock 23 off-duty.  

All cars have a Mossberg M590 18" with ghost ring sights.  Patrol officers may draw out a Ruger Mini 14[V] to carry in the trunk.

ERT dudes have Colt ARs (mostly M4 types) or H&K MP5s which they carry in their trunks.  K9 officers have 14" shotguns along with some ERT guys.

On a side note, any AK fans out there?  I work with Troy Sellers of IN RANGE.  He is a good guy and does great AK work.

Beretta 96 for duty

back-up has to be .380 or larger, DAO or DA first shot.

off duty anything you want[50]

1. primary SIG P226 .40S&W
2. REMINGTON 870
3. BERETTA 84F BACKUP ISSUED.
4. THOSE WHO PASS A 3 DAY COURSE ARE AUTHORIZED TO CARRY AR-15.  
5. ERT OFFICERS MAY USE SIDEARM OF CHOICE ON SWAT ACTIVITIES.
6. CAN CARRY BASICALLY ANY BACKUP WEAPOPN YOU QUALIFY WITH IF YOU DONT LIKE THE BERETTA

Adam556.....join L.A. Sheriff,,,you have more to choose from....lmao...

Issued for on/off duty or back up:

*Beretta 92FS 9mm

Authorized on duty alternates:

Hk USP .45 (full size or compacts)
Ruger .45 (various models)
S&W .45 (various models)
Beretta .45 "cougar"

***note, all on duty above mentioned guns are also authorized for off duty and back up.***

Offduty/backup only:

*Beretta Vertec 9mm, (soon to be on duty authorized too)

*S&W 39, 59 or 69 series or new "tactical" 9mm series

*Hk P7/M8 or M13 9mm

Any Ruger, Colt and S&W .38spl with a 4" barrel or less.

Shotguns: Ithaca Model 37's with 14, 16 or 18" barrels

Rifles: Only those qualified and its hard to get them deployed: Colt AR-15's

Swat can use anything they want:
AR-15 M2's
M4's with full auto
Hk, G3's with full auto
Mp-5's 9mm
Benelli M1 and M3 super 90's
Remington 700's in .308
1 Remington 700 in .300 win mag
suppressed .22 lr's, for street lights or sentry dogs or whatever they want etc...

and...my favorite....3 BELT FED M-60'S!!!! (surplus from gov't.)  Got them just before the famous N/Hollywood bank robbery.  Too bad they wern't used.....Maybe when Al Queda gets here some day.

Department authorized duty ammo:

*38spl  Federal 110gr +P+ sjhp (optional Gold Dot 125gr +P0
*9mm  Winchester 147gr Ranger SXT
*.45  Winchester 230gr Ranger SXT (optional standard or +P)

*12ga. Winchester/Remington/Federal 2 3/4" 12 pelleted 00 buck or optional 27 pellet #4 buck

*12ga. Win/Rem/Fed 2 3/4" 1oz rifled slugs

*.223 55gr Federal premium soft points

*.308 168gr Winchester "Match" ammo

Dunno about the 300 win mag...????

Swat also has several armored personel carriers.

I carry a Glock 31 for duty with aGlock 33 for off-duty/back-up.  I also have a personally owned AR15 and an issued MP5.

All new hires are issued a Glock 22.  Off-duty and back-ups can be purchased individually and must be  .380, .38, 9mm, .40, .357, .357sig, .44 or .45, carry at least 5 rounds in the magazine/cylinder and have a firing pin safety.

All personnel hired more than a year or 2 ago (I forget the date) can purchase their own weapons for duty and off-duty.  The duty requirements are the same as the off-duty I already mentioned with a couple modifications.  No .38 or .380 are permitted and the gun must hold 6 rounds in the magazine/cylinder.

Dept. issue Glock 21

Duty - (currently) Beretta 92D 9mm
Off Duty - glocks 17,19,26 , Sig 226,228 DAO , Kahr , anything 9mm and DAO.

Chief is looking at Glock 21 (.45) and Glock 17,19(9mm) for duty gun. .45 for those who want and can qualify with it and 9mm for everyone else.

I carry: H&K USP .45cal
In car: Remington 870(dash)and G36k(semi)in trunk
Department: What you qualify with.
Edited for something funny:
One of the SWAT guys qualified with a Desert Eagle .44mag just for fun.(He uses a 1911 on duty)

Daily Patrol:
Para-Ordnance 7.45 LDA in SS
Taurus 850 CIA titanium back-up
Remington 870 marine magnum

SIRT (tac team) weapons:
Bushmaster 11.5" SBR w/ M3 light
Glock 23C w/ M3 light


Saleen

GLOCK 21C, MODEL 30
REMINGTON 870
AR-15, MINI 14, H K IN 223 (OFFICERMUCH PURCHASE)

1. Glock 17/19/22/23/34/35 depending on how I feel.

2. Backup....Glock 26

3. Car.......Semi M4 Carbine, Remington 870


Department issue...Glock 17/19, Smith and Wesson 5906/4506/3906/3913

Glock 17
870
AR15

Glock 23 .40

1. G21 .45ACP w/LEO mags
2. Dept. recently changed from SW4506 (boat-anchor, no offense) as standard to any major manufactured double action .45ACP

Rem870 carried in overhead rack, AR's kept at PD armory to gather dust.

No back-up weapons allowed due to old-dog myth about throw downs (if you can f'n believe that shit). The department requires the carry of a pocket knife to facilitate cutting of seatbelts so I carry a Cold Steel XLg Tanto Voyager [}:D]

It's taking time but attitudes are changing.

1. Sig 229 duty weapon. Big enough and heavy enough to handle the .40 round, small enough to carry off duty.

2. Glock 27 on my ankle. Took awhile to get used to the width, but imho a backup should be the same caliber as the primary weapon.

3. Rem 870 in rack.

Glock 22 w/ streamlight

Glock 26 backup / off duty

Rem 870 in cruiser

No rifles allowed at our dept, unless you're a supervisor who can carry an AR in their vehicles.

Issued: Beretta M96 .40 cal
Shotgun: Remington 870 (must qualify/optional)
Backup: Any pistol over .380 cal that you can qualify with.  I carry a Glock 27 .40 cal.  I carry a Glock 23C off duty.  I'd rather have an issue Glock sidearm but that will have to wait for some changes.  Check out our website:
www.eastpointpolice.org

I work for the U.S. INS. [(:)]

Plain clothes folks get the H&K USP .40 Compact LEM/DAO.
Uniforms carry a Berretta 96D Brigader (also DAO .40)
Individual purchase of Sig 229 DAO .40 (but no longer authorized after this year)

Pistols are issued with night sights and 6 mags, and no modifications allowed, not even aftermarket grips!

Some can qualify to carry a 14 inch 870.  Same weapon on duty and off.  No backup weapon allowed.  Rumor has it we have M-4s and MP5s somewhere, but I have yet to see one.  Rumor has it 96Ds will be phased out for full size USP .40 DAO.  But you know how rumors are...

Duty load is a Federal or Remington 155grn JHP.  We qual 4 times a year and have practice ammo issued each quarter.  
Very generous with the ammo, but really restrictive on the weapons...