Here's the actual differences between the Wingmaster, the Police, and the Express guns:
The Express is Remington's "budget" gun, made to compete with the cheaper to make Winchester and Mossberg guns.
The Wingmaster is Remington "Cadillac" top-of-the-line sporting gun.
The Police is a Wingmaster with a dull finish and is a much more carefully inspected and built gun.
How Remington lowered the Express price was to reduce hand labor to a bare minimum, and to eliminate much of the polishing and de-burring the better quality Wingmaster and Police guns get.
The Express is basically the same forged and milled steel receiver and heavy-duty internals gun the better 870's are, just in a rougher, less well finished form with plastic and MIM parts.
The Express Model has:
A plastic trigger group.
The dimples in the mag tube and the new style plastic magazine retention system, EXCEPT on the extended magazine version, which does NOT have the dimples.
A rougher finish inside and outside, with machine marks and some burrs left.
A rougher, bead blasted blue job.
A less polished bore.
A two piece barrel. (not 100% sure about this)
Hardwood or synthetic stock, with a sporting-length fore end and pressed-in checkering.
The Defense version has 18", Cylinder bore barrel, with a bead sight.
Some Metal Injection Molded (MIM) parts, like the extractor.
Has the locking safety button.
The Wingmaster has:
An aluminum trigger group.
The old style magazine retention system.
A much smoother finish inside and out, no machine marks or burrs.
The Wingmaster gun receives a higher level of inspection and finishing.
A fine, commercial polished blue finish.
A polished bore.
A one piece barrel.
A chrome plated bolt.
Walnut stocks with the famous "Bowling Pin" finish in gloss or satin and better checkering.
Wide choices in barrel lengths and choke options.
No use of MIM parts, the extractor is milled.
The Wingmaster is the full top-of-the-line commercial Remington pump gun, and is priced accordingly.
The 870 Police has:
An aluminum trigger group.
The old style magazine retention system.
A much smoother finish inside and out, no machine marks or burrs.
The Police gun receives a higher level of inspection and finishing.
A military-grade parkerized finish.
A polished bore.
A one piece barrel.
Walnut or synthetic stock, with a short police-length fore end.
The Remington “R3” super recoil pad that reduced felt recoil by 30%.
Choices in different stocks, including Speedfeed, and others.
18" to 20" improved cylinder barrel, with a wide choice in sights, including rifle, ghost ring, and luminous.
Police options like magazine extenders, forearms with built-in lights, and sling swivels.
Heavy-duty magazine spring.
Heavy-duty trigger-sear spring.
Sling swivel mounts.
No use of MIM parts, the extractor is milled.
The Express is a "bottom of the line" budget gun, the Wingmaster is a "top of the line" sporting gun, the Police is the top-of-the-line in defense guns.
The 870's are generally considered to be the finest quality pump gun made.
Here's what Remington says about their Police guns:
REMINGTON ARMS COMPANY, LE DIVISION
Important differences between Remington 870 Police and 870 Express shotguns
The 870 Express has been an important part of Remington’s offering to the sporting market.
It was designed to meet a price point in the commercial market while still providing classic 870 functionality.
All of Remington’s 870’s have interchangeable parts, even if they have cosmetic differences.
It is also important to note that many manufacturers use the 870 Express platform for their Police / Combat models.
Without exception, every manufacturer who utilizes our 870 platform serves to upgrade their system to a more efficient, street worthy platform.
While the 870 Express is still an 870, the best pump shotgun on the market, there are some very important cosmetic and functional differences between it and the 870 Police.
To our customers in Law Enforcement, Military, Corrections, and Security, whose lives depend upon the unfailing performance of Remington shotguns, the Police modifications are of paramount importance. Synopses of the variances are provided below.
• 870 Police shotguns go thru a special 23 station check list – ranging from visual inspection, functional testing, test firing, and final inspection.
• All Police shotguns are assembled in a “special build area” at the plant in Ilion, NY. This section is secured and serves only to build LE and Military shotguns, with the same factory personnel working at that assignment each shift.
• All parts that enter the “special build area” are visually inspected by hand to ensure top quality and functionality.
• Due to heavy recoil in buck and slug loads, all 870 Police guns have a longer magazine spring which ensures positive feed and function.
• A heavier sear spring is used to generate a reliable, positive trigger pull between 5 and 8 lbs.
• A heavier carrier dog spring is used to ensure when the carrier elevates the shell, it will be held there until the bolt can push it into the chamber. This ensures positive feeding when using heavier payload rounds.
• Police shotguns do not have an ISS (Integrated Safety System) which is a locking mechanism on the safety of commercial shotguns. This type of locking mechanism can cause delay to an officer who needs the weapon but does not have the appropriate key. LE shotguns have the standard, proven, cross bolt safety.
• The fore-end on the Express model is longer and not compatible with many police shotgun vehicle racks.
• The Police shotguns utilize the heavy duty SPEEDFEED Stocks and Fore-ends.
• The Express model will not allow for the addition of an extension tube without physical modification to the tube and barrel, which can nullify the warranty.
• The Express model has a BEAD BLAST BLUE finish while the Police models utilize either High Luster bluing or Parkerization.
• The Express model utilizes a synthetic trigger housing while the Police models use a compressed metal housing.
• The Police shotgun barrel is locked down with a “ball detent” system in conjunction with the magazine cap vs. a lesser grade “synthetic magazine spring retainer” lock down as used on the Express system.
• The receivers used in Police guns are “vibra honed” to smooth out rough finishes and remove burrs before parkerization or bluing.
• Police shotguns use machined ejectors and extractors, as opposed to powdered metal cast which are utilized on the Express models.