So I put all of the below on the Tinkers Construct page and they told me that it had nothing to do with them and to ask it here, so here I am.
"So recently, (I know it's super late) I updated from MC1.7.10 to MC1.12.2. In 1.7.10, TinkersConstruct automatically added the Carbon(and maybe more) material to TinkersConstruct's weapons. However, now in 1.12.2, none of the materials from Techguns have weapons or parts in TinkersConstruct."
They said:
"Tinkers Construct does not automatically add those, I assume it was added on Tech Guns side and never got ported."
Is this true? Can this get added?