Sig Cross .308 Barrel corrosion?

[JacketDeep]

Hello Everyone!
Been dropping in and out of the Hide for years, finally decided to join up so I could ask some experts about an issue that’s just bugging me.
Sorry for the chapter, wanted to include the details…
I purchased an Sig Cross in .308 at a lgs for a decent price about a month ago. Love the whole gun, for what it is. Shot it 3-4 days after I got it home.
I shot 3 rounds of Hornady Match 168 factory ammo on it, just to get the scope close, then screwed on my CGS Hyperion and fired 7 more for a total of 10 rounds. It was getting dark so I called it quits. I unscrewed the can, pulled a clean bore snake through it 5 times and pushed an oil patch through. Now here is the rub/goof. I put the Supressor back on and stood it up in the safe, stock down. I had plans on taking out the next weekend. When I pulled the rifle out at the range the next weekend, I unscrewed the suppressor as I was trying a different round (Baffle strike test). I was horrified to see fuzzy rust all inside the muzzle end of this supposedly stainless barrel? I couldn’t believe it. I cleaned the barrel slick and it looks baaaad. I’ve seen since that it’s a bad idea to store a can on a rifle as it can condense and cause this possibly? It was an oiled bore and a stainless barrel though; is this possibly a barrel issue? Is this something I should ask Sig about or is this just my own stupid tax? I store 5 other rifles on and off this way before I got the Cross, and the Cross is the only stainless barrel rifle of the bunch. Willing to hear it’s my fault, but it seems crappy that this $1500 rifle has a “stainless” barrel that did this in one week, while every other rifle treated the same, in the same safe, has been and is fine. I shot it looking like this and it still groups 3/4” at 100 yards with 175 FGMM, so I guess it’s fine for its purpose, I just hate it’s like this. Only barrels I can find to replace are $7-800 and that’s a hard pass; if anyone is upgrading to a carbon barrel and has a factory barrel hit me up. Pictures attached. Beat me up about it, I can take it.

 

[KnowNothing256]

I made a similar mistake with a different bolt gun once, put it up in a case a couple hours into a cooling evening, so a lot of condensation got boxed up in there with it and pitted the bore. Made me sick.

I don't think you need to go so far as a rebarrel if it's just at the muzzle; you can just chop the barrel back past the pitting and have it recrowned and threaded. As for the cause on a stainless barrel, I could speculate but that's all it'd be. Sorry bud.

 

[JacketDeep]

I made a similar mistake with a different bolt gun once, put it up in a case a couple hours into a cooling evening, so a lot of condensation got boxed up in there with it and pitted the bore. Made me sick.

I don't think you need to go so far as a rebarrel if it's just at the muzzle; you can just chop the barrel back past the pitting and have it recrowned and threaded. As for the cause on a stainless barrel, I could speculate but that's all it'd be. Sorry bud.

This is the first time -I- have goofed a bore, (if my actions caused it) and man sick is the right word. I just want to know if it’s possibly a metallurgy issue. Sure don’t act like stainless, it pitted like red iron.

It’s a .308 Cross, so the barrel is already short at 16”. If it was an inch longer I would have already done exactly that; the Sig taper can’t be too hard to replicate at the shoulder. But not sure it’s worth a tax stamp to cut it….might be the first 14.5” SBR version to exist though. Hmm…

 

[jbell]

Stainless can rust / corrode, that said there are different stainless out there. Check it with a magnet, I have had a few “stainless” barrels that were noticeably ferrous. Not that this helps your current situation. As stated possibly cut it back and drive on if it was a shooter before. If not do a cost evaluation of a new barrel vs the machine work to cut that one back.

 

[hlee]

Stainless does not mean rust proof.

Every year, someone buys a stainless muzzle loader with the expectation that they won’t need to be as diligent about cleaning as with a carbon barrel. They usually end up with a tomato stake.

I have stainless kitchen knives with rust on them from sitting in a dish washer after the clean cycle.

I’ve never seen a suppressor cause condensation (in hot humid Houston) but I have read that it can happen. I have a couple of rifles stored with suppressors attached- they are kept muzzle down.

 

[cas6969]

You can have a muzzle/crown counter bored, but I don't know that I've ever seen it on a precision rifle, if it would effect how it shot I don't know, usually it's for battle rifles to fix cleaning rod wear and crown damage. That may go a little farther down than normal too.

Couldn't hurt to contact SIG and ask them if and how much for a new barrel.

 

[redneckbmxer24]

Some of that looks like pitting. I guess it’s more Sig “quality”.

Best thing you can do to a cross is to sell it and buy a fix.

 

[whatsupdoc]

Leave it ALONE it will 99% shoot just fine.

If the bore is damp or wet and you put oil in it the oil only traps the moisture.
The oil does not displace the moisture.

 

[JacketDeep]

You can have a muzzle/crown counter bored, but I don't know that I've ever seen it on a precision rifle, if it would effect how it shot I don't know, usually it's for battle rifles to fix cleaning rod wear and crown damage. That may go a little farther down than normal too.

Couldn't hurt to contact SIG and ask them if and how much for a new barrel.

That’s not off the table; I’m unsure of muzzle integrity with a suppressor attached, I don’t know what the structural limit would be before that effectively thinned material under the threads would become a break point.

Some of that looks like pitting. I guess it’s more Sig “quality”.

Best thing you can do to a cross is to sell it and buy a fix.

Yeah, I’ve seen a few of these “Sig Quality” post, so that’s possible I got one of the Friday guns. I’ll give em a chance to reply about it I guess.
I would like a Fix, but it’s twice the cost, and I jumped on the Sig to see if this type of rifle was in my roadhouse. Beside this one issue, it has been indeed. Plus the Fix should use AICS mags at the price point, IMHO.

Leave it ALONE it will 99% shoot just fine.

Yes, that may be the end result. 3/4 MOA off a bipod with factory ammo is great, and that’s what it shot with a 5 round group of 175 FGMM.
It’s just knowing it’s there, and hopefully it doesn’t keyhole a bullet into my supressor one day. Probably invalid concern on that front.
I’ve sent an inquiry to Sig and will follow up here with what they say. The LGS I purchased it from was also very interested in what Sig would say about this, as they haven’t seen anything like this, and they all have multiple suppressed rifles in store and use. Thanks all for the constructive contribution! Will follow up if I hear anything.

 

[CNJarvis]

My money is on a defect in the barrel steel. That putting looks awfully deep and awfully localized. Too much so IMO to have been caused by rust, particularly since it’s a stainless barrel. The last photo is particularly suspicious. Look at the corner where the land meets the groove and you’ll see a somewhat triangular “pit” right at the end of the bore. It really looks to me like that pit was there when the crown was cut.

 

[Greg M]

@JacketDeep After reading this thread and looking at your pictures, it is possible that the SIG machinist removed metal from your barrel a little too fast and (as a result) changed the crystalline structure of the metal at the end of the barrel. My master's research was sponsored in part by Ford and was focused on the manufacturing of camshafts, so I have some familiarity with these types of manufacturing / QC problems. If this is the case, you might be able to argue for a refund with SIG.

 

[JacketDeep]

Thanks for the info; Sig requested pictures after I contacted them; after I sent the pictures they ghosted me. I’m going to try again to contact them, 1 month after is long enough to at least say “not our problem”, or preferably “let’s see what we can do”.

 

[pineoak]

Sorry if this sounds stupid, but would it make a difference if we ran a barrel cooling fan through it for a few minutes before packing it up?

If the temp of the barrel is lower?

Or would we just be blowing the same amount of ambient moisture through the barrel?

 

[Greg M]

It is not a dumb question, though the practicality is probably low. Moving air with a fan through the barrel would both cool it faster and cause any condensation to evaporate more quickly. The hard part would be channeling the air so that it flows through the barrel.

 

[pineoak]

I was thinking of this:

Riflekühl Barrel Cooler by MagnetoSpeed

Tired of waiting and waiting for your rifle to cool down? MagnetoSpeed’s new barrel cooler, Riflekühl, is designed to get barrel temperatures down to intended operating levels quickly. The turbocharger-inspired impeller is engineered to produc

magnetospeed.com

 

[Greg M]

I was thinking of this:

Riflekühl Barrel Cooler by MagnetoSpeed

Tired of waiting and waiting for your rifle to cool down? MagnetoSpeed’s new barrel cooler, Riflekühl, is designed to get barrel temperatures down to intended operating levels quickly. The turbocharger-inspired impeller is engineered to produc

magnetospeed.com

That solves the issue with focusing the airflow. It is an interesting gadget though I would have a lot of questions before thinking it might have an effect on condensation. It is advertised as a cooling mechanism. On some level, it would likely reduce the moisture build up in the barrel.

My belief when posting to this thread is that the pitting in the picture was a result of the machining process (specifically the heat it causes) changing structure of the stainless steel.

If I am right, the effect of that gadget would not solve the problem.