Creating holes in gun barrel?

[ethan.penn6]

So I started modeling a Browning M2 the other day, and I realized that dealing with the holes in the barrel (for heat dissipation) is way harder than I thought about for 3D modeling. I tried using Geopoly to make the circular holes, but the topology was all messed up after that, and it didn't look like a cylinder anymore. The closest thing that I got to work was the ProBoolean option with a cylinder. I was able to section off the booleaned part and duplicate it four times to get a circle on the top and bottom, as well as both sides. The head sinks in the gun however, alternate. They aren't all in a row. The second set is offset diagonally. I did the same thing, and while it was successful, to get the topology to work properly, the vertices no longer line up.

I wanted to get some input. What method would you guys suggest for creating something similar to the barrel that is in this image?

http://browningmgs.com/Info/Images/Barrels/fig19.jpg

[leeminardi]

You can use the array function twice to create a collection of cylinders that can be subtracted from the barrel with Pro Boolean.  In the image below I positioned one cylinder just up from the base of the barrel then used array.

The next step is to position a cylinder 45° and halfway up from the first and array it (with one less in the barrel length direction).

Here is the result.