When assembling an AR BCG, do you lube the gas rings/BC bore?

[BurnOut]

So I was just watching a Youtube vid where a guy was going over the various parts of the BCG and explaining the functions of the various bits, and one thing he mentioned is that you're not supposed to have any lube on the gas rings.

This was a WTF moment for me, because I have always paid particular attention to the gas rings, ensuring that there is a good coat of oil not just on the rings but also in the bore of the bolt carrier where the rings cycle. I admit that no one has ever told me that I need to apply oil to those locations, but coming from an automotive background, one of the big no-nos on a fresh engine is to have no lube/metal-to-metal contact between the piston rings and the cylinder bore; the last thing you want to do is gouge/scratch the bore.

Obviously, there is a difference in function between the rings of an engine and the rings in an AR (in an engine, oil is splashing around, and frequently coats a lot of the bore... and needs to be scraped as clean as possible to minimize oil consumption/burning), but applying oil to the rings/BC bore would seem to be a good practice to minimize wear to the rings or the carrier its self.

What do you guys do?

 

[mercracing]

I usually put a light coat of motor oil on the rings and make sure they are evenly spaced apart.

 

[Mormegil87]

I spray CLP on the carrier and run a little extra into the lube ports on the ejection side. Can't recall ever having a non-mag related malfunction.


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[black5.3]

Yeah i always lube it but i dont go crazy on the oil. It ends up blowing most of it out of the ejection port and ends up on my sunglasses lol.... i definitely oil that area though.

 

[Black max]

Yes oil them, and stop watching arfcom slap dicks you tube channels.

 

[BurnOut]

Yes oil them, and stop watching arfcom slap dicks you tube channels.

Eh, the vid I watched was: https://www.youtube.com/watch?v=5YlkY2KZHxM&index=71&list=PLFENSfZVVLqRpote2GFiwK5W2EBgU24XP

In any event, I figure that I can always learn something new... for instance, in the above vid, I learned about checking extractor cam-out (though I have to admit that I don't understand how allowing additional inward travel of the extractor would increase extractor tension on the rim of the case... unless the extractor is resting on the limiting surface with a case locked into the bolt)...

 

[Black max]

Like I said, slap dick. It's a bolt not a bolt face or bolt head...

 

[z28kid]

I always have lubed it as well.

 

[sandwarrior]

They are supposed to be lubed. With the rifle fully assembled, note where the two "lube holes" on the bolt carrier sit when the action is closed and ready to fire. Those two holes sit right over the bolt rings. The lubrication helps them slide without friction in high stress firing and sustained firing inside the carrier.
Lube them but don't go overboard.

 

[Yondering]

They are supposed to be lubed. With the rifle fully assembled, note where the two "lube holes" on the bolt carrier sit when the action is closed and ready to fire. Those two holes sit right over the bolt rings. The lubrication helps them slide without friction in high stress firing and sustained firing inside the carrier.
Lube them but don't go overboard.

Well to be fair those are really exhaust ports to dump pressure once the bolt reaches full travel, but we do put oil in them so they are often referred to as lube holes. The real purpose of them is not lube though, it's pressure relief, which is what dictates their location.

I always put a couple drops of oil on the rings and on the bolt tail when re-assembling a BCG. For regular mantenance, I put oil in the exhaust ports for the rings and the lube port for the bolt tail.

 

[Bigjake83]

Black Max is 100% Correct, Run that Bitch Wet!!...

Slip2000 or M-PRO7 is my Go To Lube.

 

[sandwarrior]

Well to be fair those are really exhaust ports to dump pressure once the bolt reaches full travel, but we do put oil in them so they are often referred to as lube holes. The real purpose of them is not lube though, it's pressure relief, which is what dictates their location.

I always put a couple drops of oil on the rings and on the bolt tail when re-assembling a BCG. For regular mantenance, I put oil in the exhaust ports for the rings and the lube port for the bolt tail.

I can tell you they never called them exhaust ports when I was running an M16A1 back in the early eighties. If gas wasn't being relieved from the separation of the gas tube and gas key, you had bigger problems.
Next, don't fuck with the gas rings! Make sure the gaps are offset and that's it. Taking them on and off all the time will weaken and break them. And, while I know he was doing a shop teardown, don't go taking out the ejector pin. The extractor needs only to grab a case solidly and yank it out. If it doesn't measure out (.015" ER the video) replace it. If you want a failure, leave file marks on a high stress/high motion part.. How did he measure across the lugs and come up with .082"? Maybe I can't see what he did 'cause I'm on my phone though.

Added: I would not use a case as a guide to see whether or not you need to make changes to your extractor. I would try to find the correct guage.

 

[NukeMMC]

Yep, a drop or 2 on the rings and a q-tip inside & out on the bolt for a light film.

Back in the early-to-mid 90s, the kind folks up at Crane advised a bunch of us poor, unsupported Navy competition shooters of a concoction they developed to help cure their troubles getting the then-SR25 sniper rifles (pre-MK11) to function reliably. They found it also helped the M16 rifles we were just starting to use as competition rifles.

1 part LSA 1 lubricant - general lubrication properties & corrosion protection
1 part Aviation Hydraulic fluid (the red stuff - Aeroshell 4 is what I use) - penetrating, corrosion protection and lubrication under pressure
2 parts Synthetic 2-stroke motor oil - I use Bel Ray MC-1 - lubrication and interaction with carbon

This mixture has worked very well for me. Tail of the bolt wipes clean, no scotch-brite or wire brush. Rifles I use it on run without issue.

I have tried FrogLube, CLP, M-Pro, Seal 1. I keep going back to my Crane concoction. Use it on any of my semi-auto pistols and both big & small ARs.

 

[BurnOut]

Thanks, all... when assembling my BCG, it's not exactly dripping with oil, but it is pretty thoroughly coated. I run some stuff called Machine Gunner's Lube with which I've had good luck over the years.

I also use the lube/vent holes in the carrier to put a couple of final drops of oil on the gas rings when finishing up my reassembly.

 

[Greg Langelius *]

I'm probably going to embarrass myself, but I leave my gas system dry.

Anything I put in there is going to get blown out whatever exit the gas vents through after driving the BCG rearward. I don't want to be dealing with oil mist or whatever smoke it generates once it gets heated past its evaporation temp.

Eventually, it becomes an addition to the carbon we are supposed to be removing when we clean the Bolt tail/BCG bits. Honest, folks, that passage the rings operate inside of is a gas piston/gas cylinder combination.

I was always taught that they run best when they start dry and stay dry. Those of us who went through Boot being trained on M-1's and M-14's were educated to keep the gas paths clean and dry. It was one of our DI's "Never, never, never, ever, ever, ever..." moments. The gas expansion area inside the BCG does the same thing, and I think it requires the same treatment. Whatever lube we put in there is going to be reduced to carbon, and become a contribution to the carbon,accumulation.

My $.02

Greg

Apparently, I am not alone in my viewpoint.

Since writing this post, I've researched "M-16 gas system maintenance". At no point did I see any official documents or studies recommending adding any lubricant to the gas rings. My own personal conclusion is that oiling the gas rings reduces reliability and accelerates the need to clean the BCG interior. The point of failure appears to be accumulating carbon increasing the force necessary to compress the bolt back into the BCG, causing the bolt to eventually fail to go completely into battery. This is a personal conclusion, If it's wrong, it's because I'm wrong.

 

[sandwarrior]

Greg,.

Something to mull on. In the "keep it dry" camp, I wonder if there is any impetus to chrome or melanite the section in the bolt carrier where the bolt tail rides?

Legit question, not being sarcastic. I also wonder if the nickle-boron coated bolt does the same thing? It might provide a smoother ride?

 

[redneckbmxer24]

Your first mistake was going to YouTube for gun advice lol.

They should be lubricated. I typically do a few drops of EWL before reinstalling in the carrier and once the carrier is all back together I put a few more drops down the cam pin hole and work it back and worth a bit to distribute it.

If if its a friction point, it should be lubed.