The phrase "further ammunition" means additional evidence, facts, or arguments that support or strengthen a particular position or argument. Full definition
Phantom Thread, meanwhile, was a surprise Picture / Director movie and, while proving incredibly popular with critics and Paul Thomas Anderson partisans (a Venn diagram that is essentially a circle), this will likely only serve as further ammunition for when PTA finally does get his Oscar in some future year. (decider.com)
Critics who have argued that the government's flagship free school policy has suffered from weak oversight have been given further ammunition as an investigation into a pioneering free school in Bradford, West Yorkshire, found an alleged trail of misused funds, unexplained invoices and improper payments. (theguardian.com)
Recent discovery by Davy et al (2010) of kilometer - wide (ten 8 - 11 kilometer and about 1,000 1 - kilometer - wide features) eruption craters on the Chatham Rise seafloor off New Zealand adds further ammunition to the Methane Gun hypothesis. (skepticalscience.com)