Fed Chamption .40 FMJ FN: Not for use with ported barrels?

[doofus47]

So I picked up some .40 on the way home yesterday and I was giddy that there was some on the shelf at Wallyworld. So I picked up random 3 boxes, including for the first time Federal Champion FMJ FN (I assume that means full metal jacket flat nose, which is what the bullets have).
Anyhow, I get home and I see a warning on the Fed box that it shouldn't be used with ported barrels or barrels that had ported muzzle breaks.

What is that about?

 

[Nanuk]

They are loaded so hot they may melt the barrel?

 

[Wreck-n-Crew]

Sounds to me like this is plated ammunition.

Plated ammunition has the possblity of peeling on the ports. If it were to may be that they are afraid a fragment may come through the port back at you causing injury.

A peeled bullet will tumble and go astray as well.

I did not know they sold plated bullets though.

 

[Wreck-n-Crew]

Actually I said plated, but possibly a thinner jacket as well.

Plated bullets use a soft lead core that the plating binds to. Jackets are typically thicker and harder than plated. Also plated are more limited in speed and pressure than Jackets.

Either way the jacket has to be thinner whether it is plated or jacketed for the warning IMHO.