Is this rust and do I have a PROBLEM

[csun_00]

I was shooting my mid length sabre today and I notice some discoloration between the front sight base and the hand guard cap. I am worried that it might be rust because it is rust colored but there is also some white. It think it might be gases from the gas tube but I am not sure. The front sight base shows no sign of rust but I do not have the tools to disassemble it. Honestly there is no rust on the cap either it is merely in the gap between the two pieces. I also think I saw some rust on the flash hinder. While I am not worried about the hinder so much.

The barrel is a sabre vanadium barrel and it has no signs of rust. Also the free float MI #18 hand guards do not show anything looking like rust. So my question is, is it rust or is it something else and should I be worried?

[Col_Crocs]

If it showed up while shooting, you may have a leak.
Tried a quick search, didnt find much in previous posts. Check the area where the leak is and maybe swap you old tube out for a new one.

[csun_00]

Here are some photos to help

[MisterWilson]

Technically rust. (on the cap)

Realistically nothing to worry about.

Non-issue, move on.

[ALCOAR]

I think its more a leak issue, because if u notice not so much the area u describe but rather on your second pic, the area around where the pin goes through FSP and gas tube seems to have some corrosion looking build up around it. It might just be me, and if the weapon isn't having any FTF's and is cycling clean..I think some spring cleaning will take all your worries away.

[Heavy Metal]

When you oil the outside of your rifle, put oil on the joints. These are the areas that tend to hold moisture from rain and allow rust to start. The gastube/handguard cap/FSB juncture is a classic spot for this. I put a drop or two at this juncture just above the gas tube from time to time to prevent this.

Looks like some rust on the FSB near the roll pin hole too.

Looks kind of dry. Park needs oil too.

[Littlelebowski]

Yes, and no.

[Col_Crocs]

On second thought, judging from the photos, looks like rust... Ya, put a couple of drops on these areas.
I normally use whatever lube I use on my rifle for these parts but has anyone ever tried penetrating oil? ve been thinking about trying it lately. Just seems like it would "penetrate" down to the under areas better. What do you guys think?

[Col_Crocs]

off topic, what rail is that?

[Heavy Metal]

Penetrating oil is not necessary.

I use CLP or Ballistol for an exterior rub-down and Weapons Shield for my internal lube.

Any one of those three would be fine.

[MisterWilson]

off topic, what rail is that?

Looks like a Midwest Industries.

[Deadcenter45]

I hit mine with Breakfree CLP then wipe off excess -perks the park right up. :)

[csun_00]

off topic, what rail is that?


Thanks for all the advice guys, I figured it was not that big of a deal. It never occurred to me to oil the FSB so I will now. So the vitals for the patient are:

Sabre 16"midlength
-Chrome lined 1X7
-As you can see F marked FSB

A Midwest industries #18 free float tube
Bravo BCG
and the ever illusive Magpul UBR
Magpul MIAD

So as you can see given the quality, I was a little concerned about the fact that it might be rusting after only about 1500 rounds.

[STJ]

To me its looks more like heat scorching than rust on the FSB...You do alot of mag dumps?

[JimmyB62]

From a similar thread. There are some second hand comments about Sabre too......



https://www.m4carbine.net/showthread.php?t=14037&highlight=leak+rust

[Jerm]

My LMT had the same thing.

LMT simply said "nothing to worry about".

Others have said that its some type of "blasting media" left over from the manufacturing process.

The consensus seems to be that its normal and nothing to be concerned with.

[miko]

i had rust in same area. So I popped out the FSB pins & slid fsb forward. I cleaned & parked the area & repinned the FSB.
Its been perfect since.

[5pins]

This is what my new LMT upper looked like this past Friday after about 200 rounds. To clean it I just used some solvent and a nylon brush. I then applied a light coat of oil and it looks like new.

http://generalcartridge.net/images/PICT2916.JPG
http://generalcartridge.net/images/PICT2922.JPG

[Jerm]

Im not convinced its rust.

If so the rust on my LMT(looks just like OP pics) go's up in little poof of smoke almost instantly when held under an open flame(bic).It leaves behind a tiny bit of residue similar to that of burnt plastic/rubber.

It showed up when the rifle was almost new.Within the first thousand~ rounds is when i noticed it.

It seems to have cleared up for the most part...Despite not really having cleaned/lubed the area in almost a year of use(1500~ rnds).

Im going to clean/lube it again today and see if its not gone for good.

[SwatDawg15]

I just cleaned a 6920 that had some suface rust as well. However it should have. The Deputy was running a warrant a week ago, and somehow fell in the yard in a mud hole or something. (I was not there) They got threw with that and he put it back in his case in the trunk. That night had a night club shooting where eight people got blasted, and he responded, ect Anyway, he forgot about te 6920 for almost a week. When he remembered it he took it out the case and seen the surface rust on and around the FSB, and the FH. He brought it stright to me.

I wish I would have taken pictures, but it looked like the LMT above. I completely striped it and cleaned her up. Looked like a brand new weapon. I checked with him yesterday, and looked at the weapon. Still looked great, so maybe its gone.

Oh, and yea he was very sick to his stomach when he discovered it with the surface rust :D