View Full Version : Corrosion on my bolt tail and bolt carrier?

05-01-2011, 9:36 PM
I was doing a thorough cleaning of my DDM4 today and I noticed some bumps around the slope of the tail of the bolt. I thought it was carbon build up so I sprayed it down with action cleaner and then scrubbed it with a toothbrush. It did not come off. I tried taking a picture but you cannot see it, so I have no way of showing everyone. I also noticed a kind of lump around the inner ring that the bolt tail is inserted into.

I only shoot Federal XM193 ammo, but did shoot 100 rounds or so of Wolf Classic when I first got the rifle. I did thorough cleaning after shooting the Wolf ammo, but did not know to use Windex, since it was listed as non-corrosive.

Am I screwed and will I have to buy a whole new BCG? Could it possibly be a warranty issue? Is it bad to shoot it like this? I have had the rifle for 5 months and have around 1500 rounds through it. I normally clean it after every use, but have not cleaned it in about 5 trips to the range. It does not seem to affect the performance of the rifle. As far as accuracy goes, I shot 150 rounds yesterday at the range and it was really windy. So I do not know if accuracy is being affected. I was able to hit the skeet and bowling pins at 50 yards with no issues (between gusts).

Thanks in advance!!!

05-01-2011, 9:55 PM
Picture would really help... but if it's not noticeable on the pic you took, I would say don't worry about it. DD makes solid stuff, most new AR shooters baby their rifles too much... go shoot it and have fun. Unless there's cracks or something more noticeable, shoot and be happy :)

Read this: http://www.bravocompanymfg.com/v/vspfiles/assets/images/filthy14_oct10.pdf (Filthy14)

As for the Windex... it's only for corrosive stuff, none of which you are using. If you have corrosion from ammo, you'll seeing pitting near the gas ports (FSB) area and some of your trigger parts. I think you're fine.


05-01-2011, 10:30 PM
ummm, unless you have corrosion on your boltface, I wouldn't worry about it.
The tail of the bolt is not an area that really effects the function of the gun.

05-01-2011, 10:44 PM
It's fine. Not a thing to worry about.

05-01-2011, 11:00 PM
Bumps? It's probably carbon. Go get a knife and scrape it off. Put away the brush and cleaner, and just scrape it off. If it were corrosion, it wouldn't be black and you've described exactly what carbon buildup looks like, and a toothbrush will not take it off.

05-01-2011, 11:17 PM
I have that same thing on my BCM bolt. It's not a problem.

05-02-2011, 6:33 AM
Use a small knife to scrape it off.
This is normal carbon build up for a DI AR15 type rifle.
It's not a bug. It's a feature. Some day it may turn into a diamond. :D

05-02-2011, 8:48 AM
Nothing to worry about.

05-05-2011, 1:30 PM
You all were right, it was carbon build-up. I scraped at it with my fingernails and it didn't come off and it looked like corrosion. When I used my carbon scrapper and it all came right off.

Thanks again!!!