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Is it safe to replace just the bolt assembly of a bcg or better to replace entire bcg? Never had done something like this so figured I would ask. The one that came with an AR I got is rusting already with less than 200 shots. I went cheap on a upper so yeah I know, get what you pay for. Just didn’t want to spend allot going into something I may dump. Going to keep it so need to upgrade a few things. It’s a Sota Arms 300 BO.

I picked up a Nickel Boron BCG that was $109 - on sale from Monmouth.

No problem swapping them.

Bearcatrp wrote: The one that came with an AR I got is rusting already with less than 200 shots.

Use Birchwood Casey's "Barricade" oil with #0000 steel wool on RUSTED spots = rust removed without affecting bluing.

Bluing is gone. Never had this happen on my 308 ARs. May change out entire bcg when my suppressor comes in. Will try your suggestion though for now.

Bearcatrp wrote:Bluing is gone. Never had this happen on my 308 ARs. May change out entire bcg when my suppressor comes in. Will try your suggestion though for now.

Excuse me, are you saying your bolt carrier is rusting? How old is the upper? How about the bolt? Chamber? Rifling? 200 rounds could be 2 weeks or 20 years old. And yes, the components are modular. As stated above, I agree about nickel boron. I swear by that coating. Thinking about coating my wife in the stuff.

Randygmn wrote:

Bearcatrp wrote:Bluing is gone. Never had this happen on my 308 ARs. May change out entire bcg when my suppressor comes in. Will try your suggestion though for now.

Excuse me, are you saying your bolt carrier is rusting? How old is the upper? How about the bolt? Chamber? Rifling? 200 rounds could be 2 weeks or 20 years old. And yes, the components are modular. As stated above, I agree about nickel boron. I swear by that coating. Thinking about coating my wife in the stuff.

Nickel boron would be good when you run suppressed.

Bearcatrp wrote:Bluing is gone. Never had this happen on my 308 ARs. May change out entire bcg when my suppressor comes in. Will try your suggestion though for now.

It's most likely mag phosphate and not bluing. Is it worn off the bolt entirely? It there rust throughout the bolt?

I would snap some pictures and contact Sota. They will likely replace it.

How the heck did you manage to do that?

How was it stored?

Had it been lubed?

Did you clean it?

I lube the **** out of all my rifles when I brake them in. Here is a photo...

Unless I am missing something, that appears to be carbon. Soak it in some carb cleaner or use an ultra sonic cleaner.

Then run it wet all the time.

striped1 wrote:Unless I am missing something, that appears to be carbon. Soak it in some carb cleaner or use an ultra sonic cleaner.

Then run it wet all the time.

That is what it looks like to me. Just needs cleaned.

Carbon, with a touch more than normal copper.

The latter part is pretty common in new AR's (especially of the gas port is on a land) until the sharp edge of the gas port gets suitably burnished.

Soak it hard in solvent, and use a carbon removal tool if you feel the need, but it's not really an issue.

I have a ultra sonic cleaner that’s collecting dust. Do I use the same cleaner that is used for cleaning brass? Phosphate coating seems to be a PITA for cleaning. My 308 bcg doesn’t have this issue. Reason why I asked about changing it out to a better one. If this is expected to build up every time, would rather change it out. Thanks guys.

Go buy this https://www.fleetfarm.com/detail/slip-2000-carbon-killer-16-oz-/0000000088462

Throw the bolt in for a while. Fish it out. Wipe it off. Lube it up. Re-install. Go shooting.