SLR15 RIFLES ADVANCED AR-15 / M-16 / M-4 ARMORING COURSE
When: April 9-10, 2014
Where: Lakewood, Ohio
Rifles represented in this course were Colt, Bushmaster, BCM, DPMS, Smith & Wesson, Rock River, Daniel Defense, and a couple of custom builds.
We conducted a 2-day (16-hour) ADVANCED AR-15 / M-16 / M-4 Armorer Course at the Lakewood Police Department. This course starts from where our standard course leaves off. Everyone was given our advanced course manual that goes with the standard course manual. Everyone was supplied with their own set of basic tools, Slip2000 "EWL" Extreme Weapons Lubricant and #725 Cleaner Degreaser, etc. Also supplied were bench vises, receiver fixtures, barrel fixtures, soft jaws, etc. We started with a review of our standard course by having everyone completely disassemble and reassemble a rifle, this included removal and disassembly of the barrel. Once the rifles were rebuilt, everyone gauged headspace, firing pin protrusion, and did chamber inspections, and functioned checked the rifle to make sure it was in proper working order.
Bolt carriers were completely disassembled. We inspected everything for erosion and corrosion. Examples of different types of forged, cast, and MIM extractors were shown. We showed several examples of MIM extractors, where they failed, and how (MIM extractors with steel cased ammunition can be a bad combination). We showed different types of finishes on extractors, and showed how these perform. We reviewed from the standard course the different extractor springs, generations of inserts, and differences in springs and treatments, O-rings and D-rings. Ejectors were inspected along with their springs. Several examples of different ejector springs were shown, and how spring treatments and materials perform. Tuning ejection was also covered. This course had 3 Colt 6920’s with broken ejector springs, these were replaced, these guns also showed signs of stress from them cycling too fast.
Firing pins were inspected for length, damage, wear, corrosion and erosion. In this class there were two different types of firing pins, and we showed a third. Everyone got to go hands on with several makes of firing pins, and see the differences first hand. We showed why it is best to stay with stock firing pins in battle rifles and not competition firing pins. Bolt and cams were inspected up close. We showed where to inspect for stress. Bolt and cams were then inspected closer for stress cracks and wear. Several examples of broken and stressed bolts were shown, to include breakage and wear and common areas and not so common areas. Machining was inspected close up, and why and how it effects performance of a gun that is not running correctly. Bolt carriers were inspected closely, with attention to the machining and finishing. We showed a couple of examples of badly machined and finished carriers, which resulted in failures and premature wear on parts. Everyone removed gas keys, and installed new ones, to include the use of the MOACKS tools (several types were supplied), and counter-staking. Discussion and examples of over-torquing were shown, and how this effected rifle performance. Examples of damaged, eroded, and plugged gas keys were also shown. We showed several different carrier key screws that are available, and showed which ones are better.
Students removed the barrels again, and swabbed their barrels to make sure they were totally free of any solvents, lube and debris. Students were then introduced to a borescope, how to use it, and what it is for. Barrels were then scoped for a close up view of what was going on inside the barrel. The areas that were observed close up were the chamber, throat and lead area, rifling, gas ports, muzzle erosion. We supplied a couple of new barrels, which allowed everyone to get an up close look at machining, chrome vs non-chrome lining, parkerizing, and Melonite QPQ. Students then inspected the barrels they brought, which allowed everyone to see wear, fouling, erosion, and damage. Most barrels present had mild fouling and erosion. There was one Colt M4 barrels that was heavily fouled, which allowed everyone to see the layers of copper mixed with lead and burnt powder. Everyone was allowed to clean their barrels with a number of different methods and solvents that we supplied like Butch's Boreshine, JB Bore Compound, Barrett Heavy Bore Cleaner, Breakfree CLP, Sweet's 7.62, Slip2000 #725 Cleaner Degreaser & Carbon Killer/Cutter, and Kroil. We showed different methods for using these cleaners, and everyone cleaned. During cleaning, people were encouraged to occasionally take an up close look with the borescope, as this allowed them to see what the different solvents and methods were actually doing. With the barrels clean, we inspected the barrels for straightness. One student thought his barrel was possibly warped, but after a more thorough cleaning it checked fine. We discussed and showed how barrels get warped and bent.
Gas ports were inspected up close internally with the use of the borescope, then gauged, and comparisons of gas port sizes between makers noted, along with a reference to common gas port sizes from various makers that are listed in the course material. We covered gas port erosion and its effects on the performance of the rifle, making note the differences we see in erosion and barrel finishes. We showed examples of gas ports that were drilled before and after barrel finishing, and people could see the difference in performance. Most barrels had mild gas port erosion, and all were within spec.
Muzzles were inspected up close, looking for erosion. All were gauged and scoped, and we showed how erosion can effect performance. Crowns were inspected, looking at machining, and for damage. There was one rifle that had a damaged crown, it was a barrel that had no muzzle device attached. Most barrels are protected by having some type of muzzle device attached like a flash hider, brake or comp. Crown repair was shown and everyone was allowed to perform repair, the one barrel with the damaged crown was repaired. A couple of the barrels had heavy fouling on the crown, which will effect accuracy, these were cleaned off. Fouling build up inside of the flash hider, brake or comp, was shown, and examples of its effects. We had one flash hider that had a huge amount of fouling build up inside the baffle, this rifle was heavily used and abused with little attention to cleaning, the fouling was removed with some effort. All muzzle devices were put back on the barrels. We showed the difference in the split washer, crush washer, peel washer, and shims, and when & how to use them. Everyone was also shown the proper way to install and remove suppressor mounts, and when thread locking agents should be used.
Chambers were borescoped with attention to the machining of the finishing, shoulder, throat & lead areas. We showed how chambers are cut, reamed, and finished. This lead us into headspace and gauges, with examples of different gauges and chambers were shown. We provide several types of chamber reamers, and showed where and how these are used. A few people took advantage and cleaned up their chambers. We moved into chamber casting, and discussed when and why this is done. We had a few people cast their chamber, and we walked this through this. This led us to show a few out of spec chambers and how these performed. We showed a chamber cast from a short barreled rifle from an agency that had the rifle blow up. This barrel had been blowing primers on Federal XM193, so the agency tried another ammo which blew up the rifle. When checked by the ammo makers, the chamber gauged at 5.56 NATO. When we cast the chamber, it was discovered that the chamber was off set to the bore, which is why it was over pressuring and eventually blew up, showing it was the machining that was at fault and not the ammo makers. Next we moved into chamber polishing, how and why. We started with everyone viewing their chambers up close, then allowed them to polish them. After polishing, everyone noticed that their chambers now had a mirror shine and were very slippery.
We had everyone disassemble their upper receivers, then inspect them for machining, stress, corrosion and erosion, and all parts were gauged to make sure things were in spec. When looking at machining on uppers, we see tolerances all over the place and usually finding more tolerance issues when compared to lowers. We showed several examples of good machining and bad machining on uppers, and how this effects the rifle running correctly and stress on parts. We had two uppers in class that had machining where the bolt carriers were running diagonal to the bore, which was causing a lot of stress and one rifle kept breaking bolts. There was another rifle that when zeroed, the rear sight was maxed out to one side for windage. Looking at this upper, the front of the receiver was machined off center, and needed to be remachined flush so the barrel was not being canted, this type of work needs to be done by a machinist. Charging handles were inspected for stress and wear, and when we see damaged here it usually due to bad machining on the upper receiver. We showed several examples of badly machined uppers in the charging handle area, which one students upper had bad machining here, so we showed how to make a slight tweak so the tolerances weren’t being stressed. Barrel types, extensions, configurations, types of finishes, receiver types, front sight bases & gas blocks, and finishes were covered in the context of how they integrate. We showed why people need to use quality and the correct fixture when working with particular barrels and uppers during installation and other barrel work. Everyone remounted their barrels and gauged them for proper indexing. Barrel extensions and upper receivers were inspected and we showed how these must integrate correctly together. We showed traditional standard feed ramps, along with what people call the M4 feed ramps, and we also showed several different makers versions of M4 feed ramps, noting that there are differences between makers. We showed a collection of bad feed ramp machining, which caused feeding issues. Everyone checked how their feed ramps integrated, and we came across a few that needed cleaning up. Everyone was shown how to clean and polish feed ramps, and then we allowed them to do it.
Lower receivers were disassembled, and we started looking at the machining. We found a few receivers that were machined so the trigger group was off center, or the upper receiver was off center on how things integrate. We showed several examples of the different ways that receivers are machined, and how the lower fit works in conjunction with upper receiver fit. We showed examples of receivers that used different sized hammer and trigger pins and why. This size difference also must correlate with the lower receiver machining and finishing. We showed why some students receivers were tougher to get pins in/out and why. All receiver holes were gauged, and we showed examples of what is the min/max specs for these and why. We showed several examples of receivers with oval shaped pin holes, why this happened, and why this is bad.
Trigger groups were gone through in great detail. During our standard armorer course, we go into detail on good & bad triggers, machining and materials used, and their effects. We reviewed and added on, going back through single stage and 2-stage triggers, trigger jobs, and the differences in quality of materials used and machining. We provided a bunch of different trigger groups for everyone to go through. A sampling trigger groups from Colt, DPMS, Geisselle, LMT, Rock River, JP Enterprises, Jewel, JARD, McCormick, Timney, Jewel, Bushmaster, etc. We also provided several trigger groups that didn’t work. Everyone was tasked with installing all of these different trigger groups to see their personalities and differences. When a trigger group didn’t work, we went through them together to show why and where the problem is. Everyone was also provided with full auto, burst, and a couple of different 4 position trigger groups. Once installed, everyone go to see what worked and how. When something didn’t work, we showed them why.
The last part of day-2 was spent on barrels and free float tubes. We showed the different ways that front sight bases are mounted, and the 3 types of pin that are most often used. We showed how front sight bases are indexed and mounted, and generally why front sight bases cannot be interchanged. We showed how we fixture a barrel and front sight base for mounting, drilling, and reaming. We allowed people to help ream and mount a few barrels. We showed how to repair pin holes, and repaired a few barrels that had damaged pin holes. We then moved into gas blocks, and showed several different styles of how these are mounted. We showed how to properly index these, countersink mounting screws, and lastly how the drill and pin them. We had students pin a few gas blocks.
We moved into free float tubes, showing several different types and makers. Everyone was given the opportunity to go hands on with a sampling of free float tubes, learning how the different concepts of how these are properly mounted & indexed, then locked down. We showed some of the fixtures and indexing tools available, which ones work and which ones don’t, and how we prefer to gauge and eyeball these for best alignment. People got to go hands on with some of the different ways that free float tubes lock in, as a good lock in is necessary when rotational stress from vertical grips, bipods, etc, will cause it to shift or come loose. We also showed how to modify some makers systems to lock them down better.
Here is a brief overview of what was covered in this course:
Cycles of Function & Diagnosis of Issues
Complete Disassembly / Assembly
Identification of Common & Uncommon Problems and Parts
Identification of Group Components & Rare Parts/Configurations
Chamber Reaming & Polishing
Accessories & Upgrades
Barrel Replacement & Modifications
Internal Barrel & Chamber Inspections
Chamber Casting
Feed Ramps
Crown Repair
Detailed Maintenance
Sight and Distance Considerations
Ballistic Issues
Headspacing & Inspections
Trigger Jobs
Detailed Trouble Shooting & Repair
M16 & Burst Conversions & Problems Association
Free Float Barrels / Foreends and Modifications
Gas Blocks & Front Sight Base (Pinning)
Flash Suppressors/Muzzle Brakes/Comps/Mounts
Tuning, Harmonics & Customizing
Custom Tools & Fixtures
CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123