rust inside M4 barel ?

Hi all,

I think I haven't put enough oil inside my M4's barel (long time ago).
Now it looks like there is some rust inside.
Do you have any idea how I can remove it ?
I tried the coca-cola tips but I do no know if it worked...

I tend to use WD40 for any rust problems always works for me

It's a tricky one as the cap gas can corrode most things. The best thing is to flush it with soapy water then rinse with plenty of clean water, this should get rid of the phosphoric acid residue, dry fully and apply an oil or WD40.

Hopefully this should stop the corrosion.

8ace

I can also recommend WD 40. Soak it and let it do it's work.
If the det pin is corroded I think you may need to use a wire brush or sandpaper. This will ruin the chrome lining, but I did not yet find another way to get it clean enough again.

Water flushing and very mild (paper, cotton tip, soft brush) scrubbing to remove remains of corrosive byproducts.
Phosphoric acid (Coca-Cola) sometimes for soaking (at least a few hours, until rust gets dark) rusted removeable parts such as detonator pin.
WD40 (careful, it can damage plastic) or silicone oil (safe to both plastic and metals) to cover and protect.

Red stuff inside the barrel is not always rust, sometimes it's leftover oxidized byproducts of cap explosion that can be removed easier than rust.

Rusted parts I found on my models so far are old Marushin cartridges (they use steel pins and bottoms), detonator pins, blocking bar inside the barrel of plastic models, top of the magazine (lips, follower, upper area. Other metal parts (non-steel) typically just get the reddish accumulation but not typical rust.

Thanks for the tips guys !