Three houses in Wren Park Close were raided by officers on Friday 4 March with two teenage boys and two women arrested.
Officers located a significant amount of cash was discovered in a safe, along with drugs and a rifle – all of which were seized.
The women, one of whom is in their 30s and the other in her 40s, and one of the teenage boys were arrested for being concerned in the supply of class A drugs, possession of a firearm without a certificate, and conspiring to conceal, disguise, convert, or remove criminal property.
The other teenager was arrested on suspicion of being concerned about the supply of class A drugs.
All four have been released on police bail as officers continue their enquiries.
Detective Inspector Steve Topham said: “Drug dealing causes significant harm across our communities and these arrests and seizures are a positive result for the law-abiding majority in Grangewood.
“As a force, we work tirelessly to bring those who pose serious risks to our county, however, we rely on our communities providing us with information about criminals who are operating in their areas.
“I would urge anyone with any information to report it to the force, in confidence, at any time of the day or night.
“All information received will help build a picture about the way in which criminals work and ensure that officers have the very best information to bring them to justice.”