This first thread, "What Parts Break in a Carbine Course?," is a long-running tacked thread in the AR Discussions forum that Pat Rogers has been doing Q&A on for almost 23 pages.  Many of you are aware of this thread, I'm sure, but some here may not be.


The second thread ("Buy once, cry once: Upper assemblies from top-tier manufacturers") is a sort of Buyer's Guide thread that I started, based on some comments/info from the "What Parts Break...." thread, to help guide people considering training toward a better purchase for that purpose.

a post-election btt, as the likelihood of people only being able to buy training and uppers becomes more and more real.....

stake the castle nut
stake the bolt key
extra bolt
extra extractor this is the most likely part to break

you should be good

I learned the hard way that the bcm gunfighter LARGE charging handle isn't practical for classes, the large latch kept getting caught on my plate carrier. It didn't break but the next class I took I used med latch without incident. I've seen a few parts come loose but not break. I've only taken 3 classes though

I see a lot of guns come through courses in the US and overseas in Arctic conditions.

At my last DM Course, here are issues that some attendees experienced:

Frog Lube gummed up in cold weather like adhesive mixed with sand.  I specifically recommend Slip2000 or some type of thick oil for the AR family, and have done so for years now.  CLP will work, but doesn't have the staying power of Slip200 EWL.  Motor oil works too, but be aware of detergent additives if that's something you're worried about.

Wolf might run for a few hundred rounds, but once a gun cools, the chamber can be caked with the laquer, and subsequent attempts to make it work will result in FTExtract malf's, even with brass case.  This shut down a Noveske AR15 right in the beginning of the Culmination Exercise on Day 2 of the course.

Aluminum gas blocks have no place on an AR15 or AR10 carbine or MLGS. I've known this since 2002 after seeing what happens when you run a DPMS Lo-Pro on high volume.  Short-stroke, gas leakage, coefficient of thermal expansion between steel and aluminum means don't do it.

If you are going to take your rifles and carbines into extreme conditions with lots of humidity and temperature shifts, I recommend Cerakote on all external surfaces where possible.  The maintenance difference is night and day.  Pay close attention to your torx and allen head fasteners, as they accumulate rust the fastest.  Then comes the lock ring and receiver end plate, along with the muzzle device.

The flash hider I got from Precision Firearms is nitrided, and is becoming my favorite of all the units I've used over the years.

Set up your sling correctly before you attend training, or get some introductory AR15 training that includes sling set-up.

I can Parrot what Pat says about Mags, Extractor, Ammunition, Lubrication, which is a basic foundation for any mag-fed repeater.

I have seen the same issue with Frog lube in a recent class.  The guy asked if anyone had some extra lube, so I whipped out my bottle of Slip2000. Just a few drops in the usual places.  But he got the same globbing issue.  We thought it was from mixing the two, but maybe it just does this on it's own.  Weather was mid 50's overnight, mid-70's during the day, but high humidity.   Speaking of oil, this is probably number one issue I've seen.  Guys come with very light lube, and have troubles once it's burns off.  

A set up I've had good success with is to KG Gunkote  the upper, including the inside surfaces, then gunkote the bolt carrier.  With a good coat of Slip2000, it really smooths things out.  Also, seems to make cleaning easier, as all the carbon seems to "float" on the oil, and can be wiped out, rather than caking on surfaces.

Check and re-check stuff like RDS mount tightness.  I had one come loose on me and couldn't figure out why my zero kept changing.  Turns out the nut on the QD lever was a little loose.

I have not had any issues with godless commie ammo.  Been shooting BCM uppers, with accurate 5.56 chambers, which I think is the key.  That and LOTS of Slip 2000.  

Seen some issues with older mags lately.  I think guys buy these used/refurb'd mags at gunshows and the feed lip geometry is off.  Recommend sticking to new mags.  

Spare firing pin retaining pin.  This is the part that gets lost when field cleaning.

Tape sling ends.  Nylon web will slip under tension.  

Bore Snakes are awesome.  Keep one in my pistol drip.  

Brake Parts Cleaner, aka "Gun Scrubber" , to quickly de-scuzz weapons in high-round count classes.  Dries things out, so make sure you re-lube completely.        

Not this crap again.

Wolf ammo derangement disorder

I have only seen trigger pins walk, and one new barrel that was bad. On a side note, I have seen at least 200k of Wolf fired over the last 8 years and never a problem.

In the courses I've been to, I've only seen one guy's carbine go down and that was an expensive gas piston gun.

My personal recommendations:

1. Do at least a basic field cleaning and re-lubrication at the end of the day. Essential? Maybe not. But maybe. And you can make it in conjunction with your daily inspection. Guys who claim to have thousands of rounds through their rifle without cleaning it, like it's some kind of badge of expertise, do not impress me.

2. Inspect. Pilot's preflight their aircraft before flight, because their life and mission depends on starting out with a known-good aircraft. You should do a detailed inspection of your firearm as well while you clean it, including the bolt components especially. Also fire control group and the security of ALL fasteners and screws like the gas block. AND the sights and RDS. Takes maybe a minute or two. This goes for pistols as well. Don't assume because the sights "look" ok, that they are secure. I've had a front sight move after a thousand rounds or so and a couple days of shooting. If you start shooting badly, CHECK the sights.

3. I'm a big fan of anti-walk pins. I have them on all my guns. I've had a pin walk and cause double fires. Never again. Cheap insurance.

4. You don't have to have an $2,500 Gucci rifle to have an accurate and reliable one. Even an inexpensive rifle is perfectly good if assembled correctly and of quality parts.

I decided to burn through a couple of mags of wolf not long ago (4140 non-chrome lined barrel).  After 60 or 90 rounds I left a round in the barrel for a few minutes while loading up other mags and letting things cool.  I had to go get a cleaning rod to beat that case out of the chamber after the rim of the case was broken off by the attempted ejection.  Obviously your experience has been different.

Buy a Torx kit, you'll instantly be the most popular dude in the Defensive Carbine 1 class.

Never fails, always a loose optic in Carbine 1.  

Instructors, you should have a torx kit, locktite too, although it's hard to keep it in your kit without that shit leaking eventually.

The last stuck case I had was a brass case after shooting brass all morning.

I broke a BCG in a DMR class. I had a backup so it wasn't a big deal.