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 semi-auto 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 semi-auto 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:


  • Introduced in 1963, one of the best and most reliable semi-auto guns made
  • First successful gas operated shotgun. Designed by Wayne Leeks
  • The 1100 was the first shotgun actually designed with the aid of a computer
  • The 1100 would fire all types of two loads without adjustments. The 11-87 is a refinement that allows the use of 3 loads as well
  • The guns are very strong and will take overloads and plugged barrels that would cause other guns to blow up

Design & Function

  • Family overview, the gun was a follow on of the 870 and shares a design commonality with the 740/760 series of rifles and the 11-87 shotguns. The trigger plate/fire control parts of all of these guns are very similar
  • Cartridge feeding and bolt lock-up (locking block) are covered in detail as you watch them occur
  • Cartridge stop operation, how the primary and secondary function. Their operation is shown and explained. The left side cartridge stop is the secondary stop and is called the interceptor latch
  • Gas system operation shown, demonstrated, and explained
  • How the cutaway in the barrel ring acts as a gas release, and how the separate impacts of action bar, bolt, and inertia sleeve against the receiver minimizes felt recoil
  • Bolt and firing pin operation shown, and the out of battery safety feature
  • Operation of the carrier, fire control system, and disconnect cycle demonstrated and explained. Who does what to who, and how
  • Troubleshooting tip; Interceptor latch operation. Why the latch was modified to have a deeper face in front of the pivot
  • Firing cycle


  • Extensive disassembly, and instructions on how to take apart those parts/assemblies not disassembled, such as the inertia sleeve from the action bars, and explanation of why some assemblies are NOT to be disassembled
  • Barrel removed and explained
  • Magazine spring retainer, spring and follower removed
  • Operating handle removed
  • Action bar/carrier and bolt removed
  • Forearm support shown and discussed
  • The bolt disassembly is shown, including the firing pin and return spring, locking block, ejector and its plunger and spring
  • Trigger plate removal shown
  • Complete trigger plate disassembly shown, including hammer and disconnector, and safety
  • Link and cartridge stop removal demonstrated
  • Action spring and buttstock 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
  • It is probably best not to use the Simple Green on the O ring as it will accelerate its deterioration by removing its molybdenum disulfide coating
  • 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
  • What old style parts should be replaced


  • Missing parts that need to be added
  • Bolt reassembly including locking block, firing pin & spring, and extractor 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 reassembly, beginning with the safety, demonstrated in detail
  • Troubleshooting tips and repair; trigger plate assembly
  • Troubleshooting tips; extractor (rules), oversize firing pin hole, headspace (how to know if its excessive and how to correct it, the CR block)
  • Magazine tube and spring reassembly
  • Action spring reassembly, how to make sure its straight, and what to do if it is not
  • Cartridge stop (feed latch) reassembly and re-staking
  • Buttstock reassembly
  • Troubleshooting tips; short cycling causes and cures
  • Piston and seal reassembly
  • Link reassembly and troubleshooting
  • Bolt and action bar reassembly
  • Bolt and trigger plate reinsertion
  • Piston assembly and barrel reassembly
  • Forend reattachment


  • Scattergun Technologies products
  • Stocks; folders, shoulders, and forearms, plastic, and otherwise
  • Magazine extensions
  • Chokes and barrels
  • Colored and extended magazine followers
  • Home defense considerations
  • Sights
  • Spare parts

Final thoughts

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 1100/11-87 owner, or someone who intends to be.

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


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