Gas Ring Melted

[MVP1973]

I have a M&P15 ORC. Have put probably less than 1400 rounds through it. I was at the range this last weekend and shot about:

40 Rounds of PMC Bronze .223
I've shot lot of these before; never had an issue.

Than I shot about 60 Rounds of Wolf HP (First time shooting steel). Notice a bit of smoke....didn't think much of it.

Than shot 50 Rounds of reloads brass. Have shot brass reloads before - no issues previous times

Next day as I was cleaning it, I noticed that 1 of the gas rings had one side of the tip/end was melted or just gone.

Any insight would be appreaciated. Thank you.

 

[storeyteller]

Have heard of this happening but never heard a good explanation. File it under 'stuff happens', get some spares and replace as needed.

 

[Foxtrot]

Get a three ring set and replace all three, don't replace just the melted one, you can find them all over the net, a few bucks for a set.

or...

get the > AR-15 MCFARLAND ONE PIECE BOLT GAS RING < about a dollar more than a three ring set.

Something to keep on hand.

Easy to replace:

1. Take out the bolt carrier group (BCG). Remove the firing pin retaining pin (that cotter pin), turn the BCG bolt end up and let the firing pin come out or pull it out with your fingers, remove the cam, pull the bolt out. Get rid of any lubricant, this will help you control the rings a little better instead of them slipping around.

2. Hold one side of the rings with your finger, with a small bladed screw driver or something like that (jewlers, etc...) in the gap in the top ring lift it up and over the shoulder on the small end of the bolt then just work it around with your fingers until it comes off. Repeat for the other two.

3. Put the new rings on one at a time. Put a ring on over the small end of the bolt to the groove then push one end of the ring into the grove and work it around the bolt until its fully in place. Repeat for the other two. One goes on top of the other.

4. Make sure the gaps in the rings are not lined up, stagger them about 1/3 of a turn apart. Put the bolt back in the BCG and put it all back together.

5. Pull the bolt towards the rear of the BCG, set the assembly on a table on the bolt end and let it stand up by its self, it should not collapse back down and should support the weight of the BCG.

6. Re-lube the bolt and BCG. Put the weapon back together. Done.

At most maybe a 15 minute job.

Before you put the bolt back in, clean everything up while you have it out and inspect the bolt. Look for any cracks or abnormal signs like scarring or pitting. Check the extractor too and make sure its working ok. Inspect the bolt carrier key on the BCG also. Work the bolt back and forth in the BCG and make sure it moves un-hindered, with the new gas rings it might take a little pressure to make it move but you should not need to force it. If you go with the McFarland one piece gas ring, it goes on the same way basically as the seperate rings but follow the instructions that come with it. Look for abnormal wear also and any signs of stray metal on the inside of the BCG where the bolt and gas rings sit and travel (that melted metal went somewhere). Make sure there is no abnormal amount of carbon build up inside the BCG where the bolt goes up towards the firing pin end.

There can be a lot of reasons this happens, but most times its lubrication related. Its more likely to happen with steel cased ammo.

 

[BillyJack2012]

If I had to guess, I would think that the steel case ammo was part of the problem. No personal experience here, just a bit of armchair expertise as I only shoot brass.

Since the steel case doesn't expand, you can get grit and crud up in your barrel and extension. You should always clean the barrel when going from steel to brass.

So a question for those that know...

If you don't clean after steel case, could there have been a small gap created between the brass and crud allowing just enough gas to blow back and melt a ring? Or could it just be a side effect of non-expanding steel casing?

 

[MichiganScott]

Since the steel case doesn't expand, you can get grit and crud up in your barrel and extension.

Hate to disagree, but if the metal does not expand to obturate the chamber, it can not be used for case material. As soon as the bullet entered the barrel, the high pressure gas would take the course of least resistance and flow around the case. The shooter would get a face full of gas and the gun would go "kaboom".

 

[MVP1973]

Thanks for info. Appreaciate it. Picked up a McFarland 1 piece gas ring. Will give it a go.