I have a Martin Marietta upper that is having a FTE problem.

If I  load a round, fire it, and continue shooting, I have NO problems.  Everything works as intended.

However, if I leave a round in the chamber for hours (ie. when hunting) the chambered round will only partially extract when fired.  1/4" of the round will begin to leave the chamber, then the extractor rips off the edge of the case.

When extracted, there is a dirty green/pale blue corrosion on the brass case.

Why?

I know the chamber needs to be cleaned.  I want to know what is causing the case to corrode, in a matter of hours, so that it will not extract once fired.

TRG

Do you have ammonia residue in the chamber?

If left in contact with ammonia, brass and copper will turn pale green.  This might explain the FTE.  It might need a good cleaning.

[img]http://photos.ar15.com/WS_Content/ImageGallery/IG_LoadImage.asp?iImageUnq=3890[/img]

I bet you have a lot of questions.
But you were the type of kid that had to try
things first.

Well...

The upper is a recent acquisition.  I am not sure what was used in its past to clean the bore/chamber.  I used a gunpowder solvent today, a copper brush, and some Gunscrubber to clean the chamber and bore.

After thoroughly cleaning the chamber, I chambered a brass SA suprlus round.  There was no brass corrosion after almost 8 hours in the chamber...

Maybe there was some copper solvent left in the chamber from its previous life?

Not sure.

Thanks guys.


TRG


ps.  ilikelegs, [img]www.tvcc.edu/faculty/ballen/images/photos/playmate2.jpg[/img]

I'm glad things are back to "normal".

LMFAO

MM419

Yes, leaving an ammonia-based bore cleaner around that area COULD oxidize the brass to the point that it becomes sticky. It would not take that long.

Well, let's hope this cures the problem.  

Check your IM devilsadvocate