Bob Dunlap is a renowned expert on most of todays and yesterdays important AND obscure firearms. He has been a warranty station for most manufacturers, both large and small. He understanding of the design, function, and repair of firearms in general is unsurpassed, and certainly includes the gun that has become the most popular repeating shotgun in America, among not only sportsmen, but also the military and law enforcement as well. In typical AGI fashion, a cut away gun is used so that you can actually see how the various parts function, move, and interact.

If you want the quick course on how to get this super popular pump shotgun apart, back together, and operating as intended, then this course is for you (if you want the long course look into our basic 108 hour Professional Gunsmith Course.)

Among the items covered are:


  • First produced in 1949, one of the best and most reliable pump guns made
  • Copies made in China and India, the Chinese version (Norinco) is still imported
  • Gun comes in many grades and finishes, with a myriad of barrel styles and lengths, Rifle sights, beads, ribs, plain. Stocks come in walnut, birch, and plastic
  • The dual action bar was a great step forward and was patented by Remington. It stopped the very common problem of action bar breakage

Design & Function

  • Family overview, the gun was a follow on of the 11-48and shares a design commonality with the 740/760 series of rifles and the 1100, and 11-87 shotguns. The trigger plate/fire control parts of all of these guns are, for all practical purposes, identical
  • Cartridge stop operation, how the primary and secondary function. Their operation is shown and explained
  • The operation of the action bar lock demonstrated and explained
  • Cartridge feeding and bolt lock-up (locking block) are covered in detail as you watch them occur
  • Action bar operation
  • Fire control system, who does what to who, and how
  • Safeties; two are automatic, and one is manual. How they work, and why. Out of battery safety features
  • Bolt and firing pin operation
  • More on cartridge feeding, action bars, cartridge stops in all of their glory with the gun disassembled


  • Extensive disassembly, and instructions on how to take apart those parts/assemblies not disassembled, such as the forend from the action bars, and explanation of why some assemblies are NOT to be disassembled
  • Barrel and buttstock removed, and explained
  • Action bar and bolt removed
  • The bolt disassembly is shown and the reason given for the later addition of the pin that keeps the locking block from coming out of the bolt when it is removed from gun
  • Trigger plate and magazine spring removal, do not forget to depress the carrier
  • Cartridge stop removal demonstrated
  • Trigger plate and carrier disassembly shown, and the hammer assembly is not removed. The reason is given
  • Safety removal shown
  • You get a good look at how the various parts fit together and interact (particularly the springs) after they are removed from the gun and Bob explains things

Cleaning & Lubrication

  • AGI cleaning & lubrication methods shown, along with the reasons for their use
  • After cleaning, dry with air gun, or in the oven on Warm ~185-200 degrees (metal parts ONLY)
  • Lubing the Bob way, and what kind he likes


  • Pins, slave and tapered, hook, punches, etc. Helpful tools to help you get this gun back together easier
  • Bolt reassembly, locking block, firing pin & spring, and extractor
  • Troubleshooting tips; extractor (rules), headspace (how to know if its excessive and how to correct it), firing pin (shapes over the years and why they changed)
  • Trigger plate reassembly demonstrated
  • Safety reinstallation demonstrated
  • Troubleshooting the flex tab system shown, reason for being given, and operation demonstrated
  • Carrier reassembly shown
  • Troubleshooting; sear/hammer/disconnector leg
  • Troubleshooting; cartridge stop reassembly and re-staking shown
  • Magazine tube reassembly demonstrated
  • Bolt and action bar reassembly
  • Trigger plate re-insertion
  • Buttstock and barrel reattachment, do not forget the bolt needs to be half open
  • Troubleshooting; flex tab demonstrated in reassembled gun


  • Safeties, Big Heads and otherwise
  • Stocks; folders, shoulders, plastic, and otherwise
  • Shell holders
  • Colored magazine followers
  • Sights and barrels
  • Stock and forearm materials
  • Chokes and barrel shortening
  • Magazine extensions
  • Mounting a scope
  • Spare parts

If you noticed how often the terms explanation and demonstration are used, you may be getting some idea of why this course is necessary for any Remington 870 owner, or someone who intends to be.

Weight0.25 lbs
Dimensions7.56 × 5.44 × 0.63 in


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