Needing some help with drill bit sizes!

[Lord of the Dead]

I would like to start drilling out the barrels on all my marines and I don't know what size drill bits too use.
I'm seeing .61 thru .80. Just wondering what sizes every one else uses.

[Lunar Camel]

The bits I use are the same size as the holes indented on the sides of the bolter barrel. Not sure what size they are but they make a perfect fit. I've even used a xacto knife blade to make the holes by sticking the point in and twisting around to get the right size hole.

[DAPHEEL]

I use 1mm high speed steel bits (quick& clean) i think that's about 1/24 of an inch or 0.04 in decimals. Sorry I don't know how they gage drill bits in the states.

[bfmusashi]

Are you trying to make it 'look right' or match the size of the ammo in the magazines?

[Lord of the Dead]

I'm just trying to make them look good!

[Kawauso]

I just went with the hobby drill supplied by GW. It's the perfect size for the sides/end of bolter barrels. I also use it to drill out pilot holes for larger barrels like meltaguns, heavy bolters or other big weapons. Once you have pilot holes in place it's pretty easy to eyeball what size drill you'd need for any given barrel.

Depending on where you get your supplies from, there are hobby sites that might be helpful in this regard.
Miniwargaming here in Canada has a really handy magnet section on their website with size guides and they combo their magnets with drill bits of the appropriate size. Generally anything that goes with the 1/16" x 1/32" Disc or 3/32" x 1/16" Disc magnets will work well for larger weapon barrels.
http://store.miniwargaming.com/category/rare-earth-magnets/

[unseelied]

The 61-80 are jewery drill bit sizes under .04 inch in diameter. Probabally too small. I use a .047 drill bit which is 3/64th for boltguns and a 1/16 or so for heavy bolters.