SLR15 AR15 / M16 / M4 / AR308 Armorer Course
When: August 25-26, 2026
Where: Buffalo, MN
We conducted a 2-day (16-hour) AR15 / M16 / M4 / AR308 Armorer course that was hosted by the Wright County Sheriff’s Dept. This was our 6th time teaching an Armorers week of courses here, and we look forward to future courses as well. The training room was set up to allow plenty of table space. There was a HDTV system that allowed us to project some powerpoint and weapons animations onto.
The student base was all Law Enforcement from all over Minnesota. Rifles represented in this course were SLR15, Daniel Defense, APF Armory, Colt, JP Rifles, DPMS, BCM, Sig Sauer, Springfield Saint, Geissele, American Defense Manufacturing, Anderson, RockRiver, Bushmaster, and a few custom builds.
Day-1 started the day by 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 why 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. We also showed how to clean suppressors and why.
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. Bolts were fully gone through, which included extractors, extractor springs/inserts/O-rings. The ejectors were removed, cleaned, and inspected.
We went through gas key installation, removal, and proper staking. Several people found that their gas keys needed better staking, which we save for the morning of day-2, as this allows people who commute home to check anything in their personal inventory and bring it in for inspection and repair.
Note: One of the SWAT Teams that runs our SLR15 Entry Rifles was on the outdoor ranges for training was having issues blowing primers on Hornady practice ammunition, but not on the Federal on all of their team rifles. During their range session, they had a primer go into a gas key and dead lined the rifle. They stopped into our class with it. This allowed me to do a demonstration of removing the plugged gas key, and install a new one with new screws. It was properly torqued, and staked, and now the gun is back in working condition.
From there we got into 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.
Note: One of the APF Armory rifles had a broken trigger pin. Upon inspection of this short barreled suppressed rifle, there were signs of it running too fast. The Officer stated that they have had their rifles about 10 months, and estimated it to have about 1100 rounds through it. I supplied him with a new trigger pin to replace the broken one. On day-2 we went through the timing session of the class, and I showed him where his rifle shows signs of it running too fast as it had signs of beating itself up. I recommended that he slow the timing cycle down due to the suppressor, and if the problem persists then to put it back into the manufacturers hands.
Note: One agency had JP Rifles, which had anti-walk pins installed for the adjustable trigger group. The anti-walk pins are used as there is no J-spring for the hammer pin. The rifles they brought to class had stripped screw heads on the anti-walk pins. With a little magic, I was able to get the anti-walk pins out, and have them traditional pins to use for the class. After class they are going to go get new anti-walk pins to get them into proper working order.
Day-2 started with a review of everything that was covered on day-1, with some greater details and myths covered. Several people brought in bolt carriers with light gas key staking, and we allowed them to check proper torque, and restake things so they don’t come loose.
We then went back into trigger groups in great details, covering single stage, 2-stage, good and bad triggers, differences and options in spring systems, diagnosing problems when semi-auto turns into burst, and showing the differences in quality of triggers that are on the market. Once done with semi-auto trigger systems, we went into select fire trigger groups covering full-auto and burst trigger groups, to include replacement and diagnosing and repairs when experiencing malfunctions.
After trigger systems, we went through the rest of the lower receivers. We covered the proper mounting & gauging, and proper castle nut staking on the collapsible stocks. Several people found unstaked castle nuts, so this allowed everyone to take advantage of our tools and get things done correctly.
Everyone stripped their lower receivers, which allowed a chance for further inspections, and we went through a session on troubleshooting. Once everyone was comfortable with the entire lower receiver assembly, they were put back together, inspected, and made sure everything is in proper working order.
Note: When gong through the front pivot pin assembly, we supplied people with our new SLR15 Pivot Pin Installation Tool. This made it a lot easier for people. We see some people struggle with this, which is why we can up with the tool. We will be using them in all future courses.
We then got into a session on the timing. This is where we cover proper cycling, covering what effects timing, and how & what happens when it is out or proper time, dwell time, suppressor issues, etc, and how to get things into proper timing. This also led us into piston systems. We covered how the piston system works, break down and maintenance of the system (Yes piston systems do get dirty and have to be cleaned and maintained), how to properly adjust for timing changed, and trouble shooting. We also covered dwell time, and how it pertains to cycling issues, and hopefully got the point across of why we do not recommend barrel lengths shorter that 11.5" on unsuppressed rifles.
Note: During the timing session, we showed examples of adjustable gas blocks, and we also showed the gas control system from https://www.riflespeed.com/, which we like as it is adjustable with a quick turn by hand to one of the 12 different settings, and is well built for durability.
We showed how suppressors are properly mounted and gauged. Several people took advantage of the bore gauges that we make, and checked their alignment on their rifles that had suppressors.
Note: One of the Officers brought one of our SLR15 Entry Rifles to class that is his personal issued SWAT rifle. He stated that the gun has been great, is shoots tight little groups and is very reliable. He brought it, as all of a sudden his zero was now about 16" high, still shooting excellent groups, just high and he cannot figure out why. Upon inspection, I noticed that he had added a vertical fore grip to his M-LOK handguard, and one of the screws for the M-LOK fore grip was super long, and was pushing up on the bottom of the gas block. I had him remove the vertical fore grip so the screw wasn’t toughing the gas block, and he went out to range to recheck his zero, finding that the gun was now shooting correctly and the issue had gone away. You could see a light bulb go on as he found the error of his installation of the fore grip. He reinstalled the fore grip, but moved it so the screws were not touching or interfering with anything. Learning occurred.
The last half of day-2 was spent on the upper receiver assembly. We covered barrel removal, mounting, fixturing, gauging & inspections. We show numerous ways to fixture a barrel into a vise, and our preference as to which fixtures/methods to use when and how. We showed how to mount, then properly torque and gauge the barrel system, which ensures it is in proper working order.
At the end of the day everyone put their rifles 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
Nomenclature
Identification of Group Components
Semi, Burst, and Full Auto Parts and Conversions
Complete Armoring Disassembly / Assembly
Barrel Replacement
Cleaning and Maintenance
Sight and Distance Considerations
Ballistic Issues
Barrel: Twist, Length, and Profiles
Gas Systems & Piston Systems
Parts Interchangeability, including Brands
Headspace
Firing Pin Protrusion
Trigger Systems
Chamber Inspection and Issues
Troubleshooting, diagnosis & repair
Gauging, Inspections, Stress & Interval Issues
Accessories and Customizing
Tool Options and Selection
SOP/MOD Accessories and Additions
CY6
Greg Sullivan “Sully”
WeaponsArmorer
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123