Three men have been arrested in connection with an alleged £300,000 VAT fraud linked to the chainsaw industry.
Six properties were searched - four in Staffordshire, and two in Cheshire - and paperwork and computers were seized along with a firearm and ammunition.
The alleged fraud involves a contrived chain of companies which reclaim VAT they have not paid, HM Revenue & Customs (HMRC) said.
The arrests follow a lengthy investigation, the spokesman added.
Two men were arrested as four properties were searched in Stoke-on-Trent and a third man was arrested in Warrington, Cheshire, when two properties were searched.
The operation was led by criminal investigators from HMRC and supported by the police.
The men were arrested on suspicion of conspiracy to cheat HM Revenue and money-laundering offences under the Proceeds of Crime Act 2002, HMRC said.