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Posted: 1/7/2007 9:27:09 AM EDT
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Is this normal? Colt 16" barrel off MT6400C, marked C MP 5.56 NATO 1/7, date stamped 05/03 Kept in gunsafe when not being used, dehumidifier working. Rest of barrells not like this.  Thoughts? I was going to sell this barrel too. Danny 
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I have never had it happen but once and not that bad. I shot a bunch of the South African surplus and had a couple barrels start to rust. Caught it when it started and cleaned them good. Never had one just rust from sitting but I keep a few of the large cans of desicant in the safe. What type oil do you use? Some do not protect as well from corrosion as others. |
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The only ammo I've ever shot in this that I did not handload was some Guatemalian. The rust came out pretty easy, I can barely tell it was there. Damn shame about this cause the barrel does not have a 1000 rounds through it. Oil uesd is FP-10 but I don't oil the inside of the barrels or the chamber. Should I? 3 more Colt barrels in the safe that look like brand new? Danny
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I put a light coat of Breakfree in mine before storing it and swab all the oil out of it before going to the range. I pretty much clean it the way the manual says except for using a bore cleaner instead of CLP for cleaning the bore and chamber. www.ar15.com/content/manuals/TM9-1005-319-10.pdf For me FP10 did not work well against corrosion. I wiped a few parts down with it I had in the garage and they developed a rust film in a short period of time. |
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For short storage, CLP works fine, but if you are going to store the rifles for longer, then they should be stored in grease. As for FP-10, ditto on the findings. Not sure why (maybe the agent that is added for the aroma), but was getting spot rusting on some parts after a few months of storage. |
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I really doubt that it is rust. MT6400C barrels are fully chrome-lined. Guatemalan ammo is not corrosive. If the inside of the barrel had rusted that much, the barrel extension should have been covered in rust as well. Likely just some fouling that changed color on you. It generally should be noted that a barrel that gets a light frosting of rust will not be ruined by it, unless maybe it is being used for benchrest competitions. Accuracy will likely be fine. Worst case scenario is that a frosted barrel will foul a little more quickly. None of this applies to your barrel though since it is chrome-lined and that was not rust you cleaned out of it. |
| I have 2 of the 20" match target barrels that are not chromed. I could find nothing on Colts comercial site that list chromed lined as part of the barrel specifications. On the Defense web site I could only find it as being specified on the Military rifles. I have never found Colt to be consistant with any thing. |
When you shoot that particular ammo you had better clean the barrel a little better, Try hot water & dishwashing liquid. & yes always run a wet (I only use CLP) patch through the barrel/chamber before storage. PS: I have never seen a barrel rust like that using Non Corrosive ammo. Are you sure the Guat is non corrosive? or is it mildly corrosive like some of the old surplus stuff used to be labled? Do you live near the Ocean in a very salty enviorment or has the gun been exposed to salt water? That can do it also. |
I'll get some CLP - PDQ, I should have been using it all along...my bad.
I'm pretty sure it was surface rust. Seen plenty of rust before. That's what I thought about the barrells, maybe I got a bad one?
True.   Do you live near the Ocean in a very salty enviorment or has the gun been exposed to salt water? That can do it also. No live in the mountains of Central Virginia, barrel has never been within 100+ mile of the ocean since I've had it. I put some Kroil on a patch and cleaned the clamber and patch came out brown. Then I hit it with some oil and I can barely tell it was something there. Barrel has always shot good, had threaded and have been testing ammo with it. Wanted to sell it and get stainless barrel, paid $200 for it. be lucky to get $100 now that I know this. Thanks to everyone for your replies. Danny  |
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