Brick size

[gtofani]

Ok, I am ready to pick up my brick.
The instructions show two sizes of brick. I have found a 9 x 2 1/4 x 4 and an
8 3/4 x 2 1/2 x 4 1/4.
The nine inch will give me a slightly thicher dome. Does it really make any difference which brick size I use?
I am leaning towards the full 9" brick with the slightly smaller width and thickness, it should make the dome curves a little easier to achieve with the smaller measurements of the width and thickness.
Also, most of the pictures I have seen on this site use a fire brick for the vent arch. The materials list says common bricks. I am thinking I should use firebricks because the heat at that area will still be very high. Thanks.

[Tscarborough]

Are you sure on the size of the smaller brick? As given, that is not modular.

[gtofani]

The measurements are two different suppliers within range of my home.
I am going with the 9 x 2 1/4 x 4 . They may be 1/4 more or less but thats what the salesman told me on the phone.

[Datadawg]

From what I read up, most firebricks are 9 x 4.5. That way you can do herringbone and other layouts with good overlay.

[gtofani]

I did not think of that, if its really only 4" as the salesman said then I cant make the herringbone floor as I need to do. Unless I cut the length and I dont want to have to do that.