The phrase "various calibers" refers to different sizes or measurements of a specific type of weapon or ammunition. It means there are different options or types available. Full definition
This show is a musical composition scored for an ensemble playing various caliber firearms. (yyzartistsoutlet.org)
The game is coming out in the middle of September 2015 and will be chock full of top - notch graphics, upgradable weapons of various calibers and sizes, new types of deadly enemies, and most of all, it will offer a complex and enticing story supplemented by a number of individual missions. (badflyinteractive.com)
Report is a musical composition scored for an ensemble playing various caliber firearms. (yyzartistsoutlet.org)