DYI is a bit wrong since given the length to length ratio of the chamber and barrel, and the diameter ratios then volume ratios can be calculated. However, the normal way to express things is either as the volumes (or their ratio) or by giving the complete set of dimensions; length and width of both the chamber and barrel.

Of course, if you do it they way you did, you need to present the numbers in a manner that makes sense;

Ratios on my gun:

Length-1:2

Width-1:3

Does that mean the barrel is twice the length of the chamber and the diameter of the barrel is 3x the diameter of the chamber? Dosn't sound very likely.

Did you mean;

- Code: Select all
` chamber : barrel`

length ratio 1 : 2

diameter ratio 3 : 1

from which the volume ratio can be calulated as;

(volume chamber)/(volume barrel) = (pi)(r<sub>chamber</sub><sup>2</sup>)(L<sub>chamber</sub>) //(pi)(r<sub>barrel</sub><sup>2</sup>)(L<sub>barrel</sub>)

canceling things gives;

(r<sub>chamber</sub><sup>2</sup>)(L<sub>chamber</sub>) / (r<sub>barrel</sub><sup>2</sup>)(L<sub>barrel</sub>)

Using the ratios in place of the actual r's and L's;

(3<sup>2</sup>)(1)/(1<sup>2</sup>)(2) = 9/2 = 4.5

Now, like

MrCrowley said, the optimal ratio of a pneumatic depends entirely on what you are trying to optimize. For optimal use of the available energy in the chamber then the barrel should be fairly long and the C:B fairly small, approaching roughly 1:9 (0.11 ratio) for a 120 PSIG chamber pressure.

For optimal muzzle velocity for a fixed barrel length, the chamber should be as large as possible. The ratio might be 3:1 (3 ratio) or more.