Switching Calibers on Impact/Crown

I'm looking to buy one of these two rifles, and want to buy extra barrel kits, but I don't know which caliber to buy so that it will have the right amount of adjustment to get the power out of the other calibers. I would think that going from larger caliber to a smaller caliber will work just fine, but not sure if there is enough adjustment to go from a smaller caliber to the larger caliber. I was kinda thinking that I would get the .25 since that will be the go to caliber most of the time, but want to have enough to swap to the .30 cal, and of course it shouldn't have an issue swapping down to the .22 (.177 is not part of the plan), or should I start with the .30 so I can always tune down instead of not having enough adjustment to tune up.
OR, are all the rifles build with the same internals, and only factory settings separate what caliber the rifle shoots...from the factory?

I'm sure this as been asked, but I am unable to find the answer I'm looking for.

Thanks for the help!
 
Yes they are all the same. It doesn’t matter what caliber you start with you can adjust the power settings to shoot any caliber you buy in the future. 
A chronograph is almost essential if you really want to get the best from each caliber. The recommend settings will get you close but a bit of fine tuning over a chronograph will help get the best speed for whatever pellet you chose to shoot. 
The new smooth x barrels are amazing. You won’t be disappointed with either gun. 
Michael
 
I have both the Crown and Impact. It really doesn’t matter which order you buy the barrel in . With the Impact right now they are coming out with the X model which is exactly the same as the old one but with the new Xbarrel Utah Air Guns whom I purchased from will be giving an replacement Xbarrel assembly when available so I will wind up having the Impact with both the ST and STX barrel. In the future when I decide to add other calibers it will cost me around $400 per caliber. If I just want a new barrel sleeve in an existing caliber that designed to work with different ammo it’s abour $110 each. When changing calibers you will also need a new magazine around $79. The crown has the same flexibility and about the same cost but tit is already an STX Barrel and sleeve . If you want to use the 700 mm barrel vs the 600mm the Impact is easier to handle. 
To switch calibers on either gun is a simple 2 minute procedure. You must familiarize yourself with the ins and out of each gun both for safety and in order to keep it working correctly. as with any rifle if you do some adjustments incorrectly you can damage it. Watch some of the YouTube videos and check with others on the blog as sometimes the videos give bad advice. On the Impact and Crown Ernest Rowe has some of the best ones.

Good luck with your new rifle.

http://www.ernestrowe.com/

 
Both the FX Impact and the Crown were designed by FX to propel pellets from .177 to .30 cal. The power-plant is the same behind all the calibers. The only difference is the barrel kit and that you need to make some adjustments to the various power settings. In theory, you are able to set up the gun to shoot the entire range of pellets from 6gr to 50gr with external adjustments. In real life you may need to change the regulator pressure and fine tune the hammer and valve for maximum power and best efficiency. 
 
Since you are looking to get the .30 cal, I would suggest the .22 also. Enough difference in caliber to make sense. (.25 & .30 are close enough to have too much overlap of capabilities IMHO)
I just ordered the Impact"X" in a .22.
My reasoning is that I need a sub 12ft/lb gun at given times for pesting. something that won't carry so much BC should I miss. ;)
But I want to have reasonable shot distance should I need it. Matt Dubber has already proven that the .22 is well capable of reaching out over 100yrds. on small game.

I was going to get the .25 in a 700mm barrel but that gun is way too long for my needs. (I still might get the 700mm barrel when FX gets the slugs sorted out) but for now I need a gun as compact as possible.)

But like stated earlier there is no difference in the power plant of those guns. They are capable of shooting .177 to .30 with no problems!

Good Luck!