Another AR problem

[arjohnson]

The barrel extension gets moved in or out. Typically not a issue with an ar-15, as everything is Mil-spec

However with .308 ARs, pretty much everything has to be checked or adjusted

The rifle was originally lubed with grease... Started having problems, so I hit it with old fashioned CALL, to rule out that problem.

I will try cleaning it, but if the problem is occuring after the carbon build up after 100 rounds, the damn thing is getting sold. That's almost laughable that one can't run more than 5 magazines before it's so dirty it's malfunctioning.

I will try cleaning it anyways and shoot a few rounds this weekend and post pictures of the brass

Contact barrel manufacturer, I'm sure they will fix or replace if it's a chamber issue.

[chp1911]

I don't believe anything is left behind. I though Nitriding is a chemical treatment of the metal and it doesn't change the dimensions at all.

This was my understanding as well.

[ViperHummel]

I've used three Mega .308 barrels and all three needed to have their chambers cleaned up. They all suffered from stuck cases with brass cased. It was incosnsitent in the first 50 rounds, so I figured a cleaning was needed. I used a Flex-Hone brush and oil to clean them up nicely. No issues at all after. The salt-bath may not change dimensions, but it can leave crud behind.

[bogey1]

The barrel extension gets moved in or out. Typically not a issue with an ar-15, as everything is Mil-spec

However with .308 ARs, pretty much everything has to be checked or adjusted

The rifle was originally lubed with grease... Started having problems, so I hit it with old fashioned CALL, to rule out that problem.

I will try cleaning it, but if the problem is occuring after the carbon build up after 100 rounds, the damn thing is getting sold. That's almost laughable that one can't run more than 5 magazines before it's so dirty it's malfunctioning.

I will try cleaning it anyways and shoot a few rounds this weekend and post pictures of the brass

I never knew the barrel had an extension, I thought it was one solid piece. Learn something everyday.

[dkf]

What exactly gets left behind?

Salts, chemical film, dirt, etc. Whenever I parts back from any heat treatment of surface treatment I make sure to clean out all holes and crevises. Threaded holes are some of the worse. Believe it or not I have seen dimension changes on parts already I have gotten back from heat treatment. Usually only tenths of thousandth but it can make a difference.

I never knew the barrel had an extension, I thought it was one solid piece. Learn something everyday.

Yep. The chamber end of the barrel threaded on the OD. The barrel extension is screwed on, torqued and pinned.

[danhr]

I've used three Mega .308 barrels and all three needed to have their chambers cleaned up. They all suffered from stuck cases with brass cased. It was incosnsitent in the first 50 rounds, so I figured a cleaning was needed. I used a Flex-Hone brush and oil to clean them up nicely. No issues at all after. The salt-bath may not change dimensions, but it can leave crud behind.

Just 800 grit or 400 to 800 grit?

[chp1911]

Salts, chemical film, dirt, etc. Whenever I parts back from any heat treatment of surface treatment I make sure to clean out all holes and crevises. Threaded holes are some of the worse. Believe it or not I have seen dimension changes on parts already I have gotten back from heat treatment. Usually only tenths of thousandth but it can make a difference.



Yep. The chamber end of the barrel threaded on the OD. The barrel extension is screwed on, torqued and pinned.

OK, The way that I understand it gas Nitriding does not change any dimensions as there is not any thing deposited or adhered to the surface. Most Nitriding is a thermochemical process that uses heat and gas to cause the base metal to become harder. Salt bath nitriding also known as Tennifer could possibly leave residue behind but I was not aware of anyone using that process on barrels other than Glock as It is very expensive to dispose of the waste left over from the salt bath process. Am I mistaken?

[ViperHummel]

Just 800 grit or 400 to 800 grit?

You should only need 800, but I picked up both in various calibers.

[dkf]

OK, The way that I understand it gas Nitriding does not change any dimensions as there is not any thing deposited or adhered to the surface. Most Nitriding is a thermochemical process that uses heat and gas to cause the base metal to become harder. Salt bath nitriding also known as Tennifer could possibly leave residue behind but I was not aware of anyone using that process on barrels other than Glock as It is very expensive to dispose of the waste left over from the salt bath process. Am I mistaken?

They don't specify what type of nitriding process they use but maybe gas nitriding. In heat treating you don't notice dimensional changes from anything that is added to the part you notice it because of the heat. When the part is heated to high temperatures it expands and thus when it does cool dimensions may have changed slightly.(especially with the changes in grain structure) Now since gas nitriding doesn't see very high temps (950-1000 deg F) and they don't have a quench in the traditional sense you have less chance of dimension changes and distortions. But you still changing the "case" around the part (typically approx .040") which can still leave scale, residue and other gunk on the surface. Having to polish a chamber on a nitrided barrel is not uncommon. Some companies it is pretty much a given if you want it to work right.(like the radical firearms .458socom barrels)

[chp1911]

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