Polish and throating??!!

[Mylhouse]

OK, so I'm a dope.
I have always kept my guns stock and fortunately have never had to have any custom work/improvements made (at least to my satisfaction). I always hear about throating the barrel and polishing the feed ramp. I get the polishing the feed ramp bit, assuming that it will help with feeding and reliability. But what is the throat and what is done to improve it?
Part two: More specifically, I have a Witness 9mm that has had 2 failures in the first 750 rounds. Both times the spent case did not fully clear the ejection port, causing a jam. Is this a function of the extractor? A rough chamber? Underpowered loads (I think I was shooting reloads)?
I'm eager to read your helpful insight.

 

[4V50 Gary]

Could also be attributed to a dirty gun. How clean is the extractor claw? Is the chamber clean? It may be underpowered ammo or even attributed to the shooter. Lack of lubrication?

At two rounds out of 750, it's still a relatively new gun. I wouldn't start polishing anything just yet.

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Vigilantibus et non dormientibus jura subveniunt

 

[George Stringer]

Mylhouse, throating opens the chamber mouth to more readily accept other than FMJ bullets. Yours is ramped so this wouldn't be a concern with your pistol. As to your 2 out of 750 malfunctions, it isn't the pistol. You more than likely either limp wristed those two or the rounds were a little underpowerd. George

 

[Mylhouse]

Thanks for the input, guys. I'll go ahead and assume it was underpowered reloads. The gun was clean and properly lubed before it was shot every time. And I've never been caught limp wristing my entire life (I'm not that type of guy).