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Oil/carbon on outside of AR 556 MPR barrel

2K views 16 replies 8 participants last post by  Redhawk100 
#1 ·
I bought my MPR (model 8514) new OOTB in mid Sept and have only put 180 rds of IMI 55gr 556 FMJ through it at an indoor range without incident.

After shooting only 10 rds of PMC Bronze 55gr 223 FMJ this past Sunday at the same indoor range, I noticed that the barrel underneath the full length of the guard was really smoking and appeared to be somewhat wet and shiny. I waited about 10-15 seconds and the smoke dissipated but not before wiping the outside of the barrel at different points underneath the guard w a Qtip (see pic) that I had in my range bag.

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I continued to shoot the remaining 10 PMC rounds from that box before running another 90 rds of the IMI 55gr 556 without further incident.

All of this to say, why would the outside of the barrel underneath the guard be so fouled after only 190 rds of quality ammo?

Stated somewhat differently, I haven’t see a field strip/cleaning video where the guard was routinely taken off as a part of non-dusty, rainy, muddy outdoor shooting conditions, or have I been watching the wrong videos?
 
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#2 ·
No, taking the handguard off is not necessary for regular cleaning. Oil that is left on the outside of the barrel will burn off ( with resulting smoke) as soon as the gun gets hot. Did you use a spray lube? Are you leaving the action so wet that lube can run out during storage or transport? If there is carbon under the handguards check the pins securing the gas tube to the gas block.
 
#3 ·
Did you use a spray lube?

Are you leaving the action so wet that lube can run out during storage or transport?

If there is carbon under the handguards check the pins securing the gas tube to the gas block.
ty for the quick reply…

- no, I did not use spray or any other kind of lube on the outside of the barrel

- no, the action has a very light coat of oil on the outer edges of the BCG

- I might be mistaken when I said “carbon” under the hand guard in as much as it’s oily and somehow picked up some kind of black film that turned the Qtip so dirty.

Do manufacturers oil the outside of barrels, and if so, then could it be that I haven’t run enough rounds thru it to burn it all off?

Lastly, should I remove the guard and remove this residue?
 
#6 ·
I'd go with preservative coating. But the only rifle I ever had close to that problem was a Yugo SKS that was slathered in preservative. It took a few rounds on hot days to cook out most of it.

Not sure how easy the barrel is to get at. But I have a suggestion. I really like Hornady One Shot Gun Cleaner (NOT THE case lube). It cleans and leaves a dry film lube coating. You might try putting on the thin spray tube and spraying cleaner on the barrel through any handguard holes. Not sure how much of the sitting wet stuff that's currently on the barrel it would take off, though. The Cleaner works best if wiped off, but won't hurt not wiping it.

If it bothers you enough and taking off the handguard is easy for you, do that. Clean the barrel and then shoot to see where stuff accumulates.

I'm wondering if sprinkling/wiping some of that chalk line marking powder on the barrel might show where the leak is happening.
 
#8 · (Edited)
Not sure how easy the barrel is to get at. But I have a suggestion. I really like Hornady One Shot Gun Cleaner (NOT THE case lube). It cleans and leaves a dry film lube coating. You might try putting on the thin spray tube and spraying cleaner on the barrel through any handguard holes. Not sure how much of the sitting wet stuff that's currently on the barrel it would take off, though. The Cleaner works best if wiped off, but won't hurt not wiping it.

If it bothers you enough and taking off the handguard is easy for you, do that. Clean the barrel and then shoot to see where stuff accumulates.

I'm wondering if sprinkling/wiping some of that chalk line marking powder on the barrel might show where the leak is happening.
ty for the perspective, and here's pic using natural light that shows just how shiny and wet the barrel is... as you can see, it's become a dust/environmental dust magnet that runs the entire length of the barrel under the hand guard.

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I've never hand built an AR, but I'm sure there's a video explaining how to properly remove/replace the hand guard as it appears that there's only two hex heads aft, and I'm thinking there has to be something else forward that's not clearly apparent. So yeah, it bothers me because it's something that I've not encountered before and neither have my local shooting friends, but more importantly, is it a symptom of another problem as you and others who have weighed in have suggested?
 
#11 ·
OP, here are factors to consider:

Oil doesn't go down the bore unless it is poured into it, so it can't make its way into the gas tube from the front and leak down onto the barrel without it being poured into the bore.

Oil won't go into the gas tube from the rear unless it's poured in there, and if some did get in there, it would be blown back into the receiver.

There is space around the gas tube where it passes through the upper receiver. If a bolt-carrier group were very heavily oiled, some could make its way through that space.

The seal between the barrel and upper receiver is pretty solid, so no oil should make it through there, either.

In light of the foregoing factors, I would concur with other posters who've opined that you are seeing preexisting oil burning off. That oil or other preservative is not uncommon from the factory. It is thick, and when heated, could migrate farther down the barrel.
 
#12 · (Edited)
I bought my MPR (model 8514) new OOTB in mid Sept and have only put 180 rds of IMI 55gr 556 FMJ through it at an indoor range without incident.

...

Stated somewhat differently, I haven’t see a field strip/cleaning video where the guard was routinely taken off as a part of non-dusty, rainy, muddy outdoor shooting conditions, or have I been watching the wrong videos?
Did you break down the rifle and thoroughly clean it prior to shooting the first time? Agree with previous posters - the description provided fits what happens when preservative is not cleaned off first to a "t". Routine cleaning wouldn't typically require removing the handguard, but I absolutely would for the first cleaning out of box and any subsequent more periodic "deep" cleaning sessions.

Ruger can occasionally go overboard with how much preservative is applied before a gun leaves the factory. My Mini-14 was the thickest with preservative that I've seen on a NIB gun. It required a full breakdown and thorough cleaning before first use or even going in the safe. A quick clean would not have sufficed. It was so thick with it that I had to set it on an old towel after removing it from the box to prevent it getting on everything it touched. My AR-566 was much lighter, but still had a fair amount present in spots.
 
#13 ·
Did you break down the rifle and thoroughly clean it prior to shooting the first time? Agree with previous posters - the description provided fits what happens when preservative is not cleaned off first to a "t". Routine cleaning wouldn't typically require removing the handguard, but I absolutely would for the first cleaning out of box and any subsequent more periodic "deep" cleaning sessions.
Ty for the perspective as I did not do (but in retrospect should’ve) the thorough cleaning that you accurately described.

For those viewing this thread, I did contact Ruger CS in Mayodan, NC a couple of hours ago about this situation, and was very impressed w the expertise of the rep who previously worked for 5 years in their manufacturing facility.

Net net… everyone who weighed in on this thread was spot on regarding all of the potential causes, and I will share Ruger’s recommendations once manufacturing reviews my case and gets back to the CS rep who assisted me.

Thanks again to everyone who shared their expertise!
 
#14 ·
As promised, here's the response from Ruger engineering that confirms everyone's first thoughts...

"I would say that you are correct, it’s probably just extra oil being burned off of the barrel from heating up after shooting. I would think that If he was losing enough gas from the gas block that he could see it coming out, then he would be having cycling issues as well. I also read on the forum where he was asking about taking the hand guard off to clean the barrel. He can easily do this by loosening the two 5/32 allen head screws and the hand guard will slide off the barrel nut allowing access to clean the barrel easily. Hope this helps."

NOTE: For those who pay attention to such details, those two Allen screws should be torqued to 50 in lbs of pressure.

Again, thanks to everyone who shared their expertise!

(as you can see, the barrel was covered in oil under the length of the guard)
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#16 ·
Guns get hot they will get any hidden oil hot and it smokes. A little oil thins out when hot and it spreads further. No matter how clean you get a gun you can always find something not clean. Every Ruger I've bought the latest two decades had an abundance of light oil all over em. Including my MPR.
 
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#17 ·
My P365 and the extra magazines I bought for it all had a thin layer of something similar to cosmoline all over them. The best way to get rid of the factory coatings is to first take as much of it off as you can with dry paper towels, and then follow that up with small pieces of paper towel with a small bit of Frog Lube dabbed onto them, with the lube being dispersed throughout the paper by folding it over the lube and squeezing and rubbing it around between the folded area. Doing this makes better use of the lube and keeps the applied substance from building up too thickly on the parts.

From there, I systematically scrub the parts until the pieces of paper towel stop coming away brown. Use small pieces so you can switch to fresh ones frequently.

By the time they pieces come away without discoloration, you've worked the good lube into the pores of the metal, too, and then you can wipe away any excess with dry pieces of paper towel.
 
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