I removed my new shield from the box disassembled it and started cleaning it and oiling I looked down the barrel and noticed heavy copper fouling in the barrel, must be from test firing at the factory.
I cleaned the barrel and the Copper was not coming out, I had to use J-B bore cleaning compound, then I could see the chatter marks and a couple of the rifling valleys were bad with gouging. Where is the quality control? this Barrel is no good it will always foul up fast because it isn't smooth. Out of all of my handguns the one with the worst chattering and rifling is my Jennings J 22 and it looks much better than this M&P Shield.

Good photography.

I bet S&W will replace it at your request.

Call them, they'll send you a shipping label. Take to Fed Ex and forget about for a couple of weeks. It will come back fixed.

If for some reason you DON'T want to do that, I think the fix for this is fire lapping.

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"He was kinda funny lookin'"

How well does the gun shoot?

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Centennial Every Day

I don't really notice any copper fouling in the barrel. I seriously doubt that S&W shoots enough rounds through the gun to result in a buildup of "heavy copper fouling".

I would try to shoot the pistol before sending it back based on what the rifling looks like. I am not sure if S&W would replace based on just a visual appearance. But, you are welcome to try.

(I don't really notice any copper fouling in the barrel. I seriously doubt that S&W shoots enough rounds through the gun to result in a buildup of "heavy copper fouling".)
The pix are after the copper was cleaned out, the copper fouling was so bad that hoppe's #9 and a bronze brush would not remove the fouling I then used Sweet's 7.62 copper Cleaning Solvent, still would not remove the copper, I had to use J-B Compound then the copper came out.
This is the point I am trying to make the test firing was at most 3 or 5 rounds even if it had been 20 the fouling would not be that bad, the fouling was bad because the barrel is like sandpaper ripping the copper off the bullet.
the barrel might function like this butt there will be higher pressure and the barrel will be a pain in the *** to clean.
I am 54 years old I have been shooting guns and cleaning them for quite some time now. I am not a noob, copper that can't be removed causes a chemical reaction between the copper and the steel of the barrel and eats away the steel this is called pitting.
A barrel like this 20, 30 years ago was unacceptable why is it acceptable today??

Oooh, that sounds fun! What's fire lapping? Soak a mop in flitz and kerosene and then light on fire and scrub your bore?

No, seriously though what's fire lapping? I haven't heard of that...

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Equal opportunity shooter

I'm starting to see a trend here lately.. Starting to read lots of posts with bad barrels, ill fitting grips, poorly timed cylinders etc. etc.. I'm beginning to think S&W has started outsourcing to China or something... I also am reading lots of advice to just see how a gun shoots, regardless of the fact that it never should have made it through a QC inspection.. In my opinion and obviously this is only my opinion, new S&W guns are nothing of what they once were. I love the hell out of my no dash 586, but it will be a very cold day in hell before I throw down any money for a new one.. As for the Shield, it's a budget gun at best. Guns are like anything else. You pretty much get what you pay for.

You light a pile of powder and lick it up....fire lapping..

No, SERIOUSLY. Put fine lapping (grinding/polishing) compound (make a paste) in your barrel with a small brush or on your bullets and fire jacketed rounds through it. Like any other polish job you can start with a grade that does some action and finish off with a finer grade to get polished. Don't over do it.

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"He was kinda funny lookin'"

Fire lapping by firing FMJ bullets through a barrel with decreasingly abrasive compounds is not my preferred method for polishing a barrel.

The goal is to smooth microscopically rough surfaces that inevitably occur in the manufacturing process. The same result occurs after firing many hundreds of rounds of jacketed ammo with a fair amount of (sometimes difficult) cleaning.

A smooth, polished bore fouls less, is easier to clean less frequently, and usually produces a slight increase in velocity and more consistent velocities. Polishing typically has no effect on accuracy.

However, some barrels are very poorly machined. The tool that is drawn or pushed through the barrel blank to cut the grooves, leaving the rifling ridges, gets worn. It will "chatter", cut unevenly and leave the barrel unusually rough, like what the OP showed in his photos. QC inspection is supposed to catch when the tool is so worn that it produces such a barrel. Cull the barrel; replace the tool. If a customer gets such a low end barrel, it is easy and relatively cheap just to replace it under warranty.

The barrel may have acceptable accuracy for a defensive pistol, but that accuracy will likely degrade as fouling builds. Pressure can build. Cleaning is very difficult and needs to be done more frequently.

Fire lapping such a barrel is like trying to make a purse out of a sow's ear. The OP said he already used JB Bore Paste, a mildly abrasive cleaner which not only removes heavy fouling but will also polish a clean barrel in a faster, easier, cheaper and more controlled manner than fire lapping, and without firing any ammo.

The amount of "polishing" needed for the OP's barrel to reduce those marks is not worth the time or effort--or the probable result of actually wearing the barrel out. Some serious metal needs to be removed from that bore to get it smoothed and polished. Hence the advice to see if S&W will replace it under warranty.

There are numerous methods available to produce a good bore. Some are cheaper and faster than others, usually reflected in the price of the gun. I suspect these short pistol barrels are usually "button" rifled. Good for price, adequate results when both the tool and the barrels are inspected frequently to ensure the tool made it through the bore properly, or has not become too worn. Every imperfection in the tool is transferred to the barrel.

The roughness shown inside of the OP's barrel would not be acceptable to me. Having used a magnifying bore scope inside many barrels to see the condition of the metal, I can tell from these photos with no magnification that this is an unacceptably rough barrel, whether it is accurate or not. Accuracy is not the only desirable characteristic of a barrel.

I think what we are seeing are a lot of complaints about cosmetic issues that have no bearing on the performance of the handgun.

Go shoot the gun and report back. And remember, it's a $300 gun, not a $3000 Wilson 1911.

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Centennial Every Day