SLR15 Rifles AR-15 / M-16 / M-4 Armorer Course
When: September 20-21, 2018
Where: Blaine, Minnesota
We conducted a 2-day (16-hour) AR-15 / M-16 / M-4 Armorer Course that was hosted by the Blaine Police Dept. This was our 6th time doing a course at this location, and we look forward to future ones. The training room offered plenty of table space, decent lighting so people could see small parts, and a large screen and projection system that allowed us to show animated graphics of the weapons system, powerpoint detailed pics of gun parts, and especially when looking at finer detail things like machining, stress cracks & wear.
The student base was a mix of Law Enforcement and Nuclear Security Officers from various agencies around Minnesota.
Rifles represented in this course were SLR15, Colt, DRMO M16A1's, Bushmaster, Smith and Wesson, Bravo Company, Daniel Defense, DPMS, Rockriver, Sig Sauer, and APF Armory.
Day-1 started with going through the course manual that all students are given. Students were supplied with their own set of basic tools that are necessary to do 95% of the work on their rifles (short of restocking and rebarreling, of which wrenches and sometimes fixtures are necessary), Slip2000 "EWL" Extreme Weapons Lubricant and #725 Cleaner Degreaser, etc. A short session of nomenclature was covered, at which time covered every feature and exterior piece of the rifle to include all the hidden design features that most people are not aware of, and everyone prepped the rifles for disassembly work. Everyone was taught the procedure series of checks that we recommend.
Everyone was taught our recommended way to field strip a rifle, and whey we do it this way so as not to cause damage, premature wear or stress on anything. We covered maintenance of where and what to clean, and what needs lubrication to keep it running. We showed why not to use the firing pins as tools. We showed everyone our recommendation of how to remove fouling and why, and everyone got to use our methods.
The entire bolt carrier assembly was covered, to include inspections, maintenance, upgrades, 3 types of gas rings, and differences in finishing and machining. carrier key (gas key) installation and staking, ejector systems, etc. Everyone was introduced to the different types of gas rings. We went through what each types does, and their proper installation order.
Note: When Officers checked their carrier key staking (gas key), they found light staking that wasn't touching the screws on rifles from APF Armory, DPMS, Bushmaster and Rockriver. These Officers used the MOACKS and Sully Gas Key Stakers that we had with us, and made the corrections.
Note: One of the DRMO rifles (Armalite/Colt AR15 marked) was brought to class as it wouldn't fully lock into battery so it could be fired. The bolt carrier was parkerized, no forward assist serrations, with a chromed bolt carrier key (gas key) that was single staked with a center punch, and the early large head firing pin. Upon inspection, I found that the interior of the gas key wasn't machined deep enough, as it's depth measured at .8445, and the other keys we had averaged at .9220. I offered to provide them a new gas key, but the agency who it belongs to had already obtained another bolt carrier that was being used in the rifle, and didn't want to repair or replace the carrier key on the one that was causing the problems.
We got into the lower receiver assemblies, starting with the fire control group (trigger group). We teach this in a building block format, starting with baby steps of getting things out and in, then build into how things work. Everyone learned how to install and remove things so you don't cause damage. We went through detailed inspections of all the sear engagement surfaces, spring types, single stage, and two stage trigger systems. The last part of the day we spent on an introduction to timing, which we like to do so that it grows in peoples brains over night, in preparation of getting into great details of timing for day-2. Everyone put their rifles back together, making sure that everything worked properly before we ended the day.
Day-2 started with a review of everything that was covered on day-1, with some greater details and myths covered. We then got into a session on the timing as it pertains to proper cycling, and showed what effects timing, and how & what happens when it is out or proper time, dwell time, suppressor issues, etc.
There were no piston rifles in this class. We showed several examples of piston systems, and their personality traits. We showed how these work, adjustments of when/when not to adjust, and covered what the pros/cons are.
Everyone in this class had collapsible stocks, and we showed the proper mounting & gauging, and made sure everything was properly staked. Everyone stripped their lower receivers, which allowed a chance for further inspections, and we went through a session on troubleshooting. We showed examples of good & bad machining on parts, and how this effects the entire rifle. Lastly we went through full-auto and burst systems, showing how these work, and trouble shooting related to such. Once everyone was comfortable with the entire lower receiver assembly, the were put back together, inspected, and made sure everything is in proper working order.
The last half of day-2 was spent on the upper receiver assembly. We covered barrel removal, mounting, gauging & inspections. Everyone was allowed to rebarrel their rifles or make adjustments. We showed why people should be picky on how barrel nuts are indexed, and why there is a torque spec. If barrel nuts are not indexed properly, it could cause stress and premature wear during cycling and excessive wear on the gas or piston system. If barrel nuts are not torqued to their minimum recommended specs, things can come loose, and if it's loosed you can lose accuracy, being loose can also be a safety issue.
Several Officers took advantage of the time & tools, removing their barrels. Upon inspection of the barrels that were removed, none had moly paste, and several of the barrel nuts were not properly aligned, and one was loose as if it was never torqued to proper spec. All barrels that were pulled, were remounted, torqued and properly indexed.
Once all the rifles were put back together, everything was inspected and gauged to make sure it was in proper working order. Everyone did chamber inspections, checked & gauged the four gas seals, firing pin protrusion, trigger press, and headspace.
Here is a brief overview of a few things that were covered:
History of the Weapon
Cycles of Function
General Disassembly & Assembly
Identification of Common Problems and Parts
Identification of Group Components
Semi, Burst, and Full Auto Parts and Conversions
Complete Armoring Disassembly / Assembly
Cleaning and Maintenance
Sight and Distance Considerations
Barrel: Twist, Length, and Profiles
Parts Interchangeability, including Brands
Firing Pin Protrusion
Chamber Inspection and Issues
Troubleshooting, diagnosis & repair
Gauging, Inspections, Stress & Interval Issues
Accessories and Customizing
Tool Options and Selection
SOP/MOD Accessories and Additions