AGI - Products Remington 870 Shotguns

Home »AGI - Products Remington 870 Shotguns

Remington 870 Shotguns


Remington 870 Shotgun

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.

How much does your Professional Course cost? The answer can be found in our intro pack. We recommend to anyone considering our Professional Course that they get the Introduction to Gunsmithing Packet as this packet includes a video with a sample gunsmithing lesson. It also includes an Enrollment Form that lists the costs of each Course level available as well as the material covered in each level.

Do I have to pay $7 s/h on each retail video? No, we discount shipping on multiple video orders. The new website calculates shipping based on weight and destination. In most cases, the actual shipping is less than listed in the catalog.

Is there a time limit to complete your course? No, our course is self-paced. As you complete sections of the course and submit your tests, we provide certification of completion for that portion of the course.

Can I become certified by taking your retail courses? Answers vary. If you are intending to purchase all the videos in our Law Enforcement Armorer's Course, for example, as long as you buy the test separately you can obtain a Certification as a Law Enforcement Armorer once you complete the testing successfully. Otherwise you would need to purchase one of our certified professional courses in order to obtain a profession Gunsmithing certificate.

What does your Professional Gunsmithing Course Introductory Lesson cover?The Introductory Lesson is one hour and includes complete information on how to get started Gunsmithing. You will also learn how to insure reliable auto-pistol feeding and how to prevent jams, checking and adjusting "range" on Smith and Wesson revolvers, how a gas system works on a Colt AR-15, AR-7 trigger repairs, timing and understanding cartridge stops of a Remington 870 and much more! 

Are your Courses guaranteed? Yes! The American Gunsmithing Institute is proud to offer a 100%, "Bulletproof Guarantee." We are so sure of the quality of our Courses and products that you may return any item purchased directly from AGI for a full refund (less shipping) for up to 90 days after purchase date. Defective DVDs and videos will be replaced for up to 1 year. The only question we will ask is: "How did we fail you?"

Does AGI offer other Certified Courses aside from the Professional Gunsmithing Course? Yes. We also offer a Certified Machine Shop Course, complete with Lathe, Mill and general Machine Shop instruction. Additionally AGI offers a Certified Welding Course and a Certified Locksmithing Course.

What do the Disassembly/Reassembly Courses cover? AGI offers D/R Courses that clearly demonstrate the complete process of disassembly and reassembly step-by-step. The Courses use close-up views to provide comprehensive instruction. Each DVD Video Manual covers one specific model or family of firearms and is indexed to help the user quickly find the information that they are looking for. At the price of only $19.97 each (plus s/h), these video manuals are must have support information for anyone who owns one of these firearms.  

What do the Armorer's Courses cover?AGI's Armorer's Courses teach you how to disassemble, maintain, repair and reassemble your choice of the 51 guns featured. These videos are packed with exclusive information and are equal to a complete Factory Armorer's Course! While our Disassembly/Reassembly Courses contain invaluable information, our Armorer's Courses contain so much more. Master Gunsmith and AGI Instructor Robert "Bob" Dunlap explains design and function using exclusive factory cutaway firearm models, giving you close-up details of the internal functions you would not otherwise be able to see. All AGI Armorer's Course DVDs include a FREE printable schematic!    

Are your Instructors experienced in their fields? Absolutely. Master Gunsmith and AGI Senior Instructor Robert "Bob" Dunlap is a widely respected authority in the firearm industry and spent over 35 years as the senior instructor at Lassen College's internationally known Gunsmithing School. Master Gunsmith Gene Shuey is a world class custom gun builder, former world class competitive shooter and current trainer specializing in 1911 and Glock pistols, IPSC limited and open class guns, and high-end custom rifles. Darrell Holland is a well known custom rifle builder, writer and lecturer who is always inventing new performance shooting products. Ken Brooks is a graduate of the renowned Gunsmithing program at Lassen College and continues his journey by working full time for Bob Dunlap. Gene Kelly is the President of AGI and the Gun Club of America. He graduated from Lassen College's Gunsmithing program and worked as a Professional Gunsmith prior to founding AGI. T.R. Graham is a NRA Certified Pistol Instructor and is a known authority, author and Gunsmith specializing in Glocks and other handguns. Master Armorer John Bush is an AGI Instructor and a consultant to manufacturers and importers of military firearms, and is certified as an Expert Witness in firearm cases.

Suggested products: