DLD already answered pretty much all there is to say. 
Regarding the cylinder sizing, as you have the X40 and don't like the huge chamber of it, I would go for either 1.75" or 2" diameter cylinder. I'd see 2" being a bit more viable option. 2.25" is close to X40 diameter to my best memory anyway.
Other than that, DLD's post has answers to your questions.
But as he wrote, if you have other questions, feel free to ask.

Regarding the cylinder sizing, as you have the X40 and don't like the huge chamber of it, I would go for either 1.75" or 2" diameter cylinder. I'd see 2" being a bit more viable option. 2.25" is close to X40 diameter to my best memory anyway.
Other than that, DLD's post has answers to your questions.

But as he wrote, if you have other questions, feel free to ask.