I’ve owned three center firing pistols and one center firing carbine over the last year or so.  One thing I’ve noticed with the three pistols I’ve owned was that the impact point on the cartridge is slightly off center on two of the pistols and center on one of them.  All three pistols were from the same manufacture, CZ.  

The carbine is an AR15 clone that I am in the process of building.  Even though I have not fired the rifle yet I did buy a snap cap and tested functionality with it.  When I was testing it’s functionality I noticed that the impact point on the snap cap to be perfect, even better than my best CZ.  

So why is that?  Is it easier to machine a firing pin hole into a bolt than into a slide?  
- Sulaco

So no ones had the same experience with there firearms?  I would assume bolts can be machined to finer tolerances because it is easier to scrap a bolt that didn’t have the firing pin hole perfect than a complete slide that had the firing pine hole just a little off.  
- Sulaco

I would guess that you are right.  I don't know the specifics of the CZ, but on say - a Glock, the cartridge is pushed up into a groove on the slide.  I would expect it to be centered left to right, but might have some leeway up and down.  Without the barrel in place the cartridge can move out the top of the slide so up/down position is determined by the chamber.  On an AR15, the cartridge is held in place from all sides so it is easy to center a firing pin hole.  As long as it is the same every time I wouldn't worry.

Sorry about my lack of proper terms.  I am very mechanically inclined but forget vocabulary easily...

Where the firing pin hits the primer on a pistol doesn't mean the firing pin hole is off center. But it could be. What it usually means is how the barrel is locking up.

Quoted: Where the firing pin hits the primer on a pistol doesn't mean the firing pin hole is off center. But it could be. What it usually means is how the barrel is locking up.

And there you have it.  A much easier way to say what I was trying to