Strange spots in receiver

[JayC]

The other day I stripped the 500, and cleaned it for something to do. :mrgreen: It didn't really need cleaning since I don't shoot it very often. Anywho, as I had it apart I noticed on the inside of the receiver where the barrel slides in are these spots. It doesn't look like rust. I'm puzzled. There's no spots on any of the barrels. I took a picture, though, it's probably not the best since that's a hard spot to get a picture of. Does anyone else's 500 have something similar? Is it something to worry about? I have had the gun for a bit over a year (all told I have less than 100 rounds through it, probably closer to about 50). This is the third time I stripped it to clean it. I didn't notice those spots anytime previous.

 

[GunnyGene]

Since the receiver is aluminum and was apparently anodized, I'm guessing there may have been some contaminant (oil or such) on the bare metal that prevented good passivation. I don't think it's anything to worry about, other than cosmetic.

 

[aksavanaman]

Almost looks like you had sand stuck between the barrel and receiver, although with that kind of tolerances, you would've felt it as you slipped the barrel back in (and out for that matter). I think Gunny on the righ path there with the anodizing... are there divots in the receiver?

If it's just the anodizing you might be able to touch it up with an anodizing pen?

 

[GunnyGene]

I did a little research on this, and I'm pretty sure that's what it is. See this:

In particular:

Desmutting: Rinsing in an acidic solution removes unwanted surface alloy constituent particles not removed by the etching process.

Which, if not removed, would probably leave the kind of spotting shown in the pic.

http://www.aacoa.com/anodizing/process.htm

 

[JayC]

Thanks guys! I was a little surprised to see it. It still feels pretty smooth. There's just the slightest hint of a "texture" to be felt. I guess there's not much that can be done? I was reading about the pen, and I found it's called an alodine pen. They aren't cheap, either.

 

[aksavanaman]

They aren't cheap, either.

Holly Cow! I've never looked up (really should do that before I give advice huh? )

I think you'll get a lifetime of use out of your 500, imperfections or not... and certainly not worth 1/3 of the cost of your gun to buy an anodizing pen! Just keep an eye on it periodically to see if it gets any worse.

 

[GunnyGene]

Thanks guys! I was a little surprised to see it. It still feels pretty smooth. There's just the slightest hint of a "texture" to be felt. I guess there's not much that can be done? I was reading about the pen, and I found it's called an alodine pen. They aren't cheap, either.

I could be wrong, but I don't think you can get those pens in different color dyes either, so you'd still have visible spots.

 

[Tanker]

Isn't it on the inside? Since it is, and no apparent structual issues, why worry about it? After about 2 or 3 times removing the barrel, it will wear away whatever you use to cover it up. Once the barrel is attached, you will never see it! I think it may be a case of worrying too much about a minor thing. It is sort of like me wwhen I was worrying about one are of my stock turned out darker than the rest. After awhile, I figured it can't be changed and moved on. Ron

 

[JayC]

They aren't cheap, either.

Holly Cow! I've never looked up (really should do that before I give advice huh? )

I think you'll get a lifetime of use out of your 500, imperfections or not... and certainly not worth 1/3 of the cost of your gun to buy an anodizing pen! Just keep an eye on it periodically to see if it gets any worse.

When I read they were expensive I was thinking something like $20. I'll keep an eye on it, but I'm not too worried about it since it's behind the barrel.

Isn't it on the inside? Since it is, and no apparent structual issues, why worry about it? After about 2 or 3 times removing the barrel, it will wear away whatever you use to cover it up. Once the barrel is attached, you will never see it! I think it may be a case of worrying too much about a minor thing. It is sort of like me wwhen I was worrying about one are of my stock turned out darker than the rest. After awhile, I figured it can't be changed and moved on. Ron

I'm not going to worry about it. Since it isn't rust it doesn't bother me too much. I realize that as the gun gets used nicks and scrapes appear in the receiver. It's all a part of its charm I guess. :mrgreen: