Do you correctly use your alpha channel? Your barrel need to be darker (in the alpha) if it is still cracks

i dont know what file go thiese cracks. Files from VTFEdit and TARGA without craks how to change alpha channel?

Alpha channel near to layers in photoshop, and yeah your own texture havn't got cracks, this is just some parts of your texture that dont render correctly, because you dont add the alpha channel, make a search in google about "alpha channel photoshop" you will find it easly.

ok thank you)