Primary Sources

I’ve been tasked with writing a paper on the improvement in weapons and artillery between 1840 and 1885 for my history class. My teacher wants me to have at least 2 primary sources, but I can’t seem to find any documents, poems, manuscripts, or letters that specifically mention weapons and/or improvements to weaponry and battle tactics during the civil war. Anyone know of any documentation written during the Civil War and the Industrial Revolution that might be able to help me?