Not exactly. "Bolter" in-universe is a slang term for projectile weapons that shoot massive (.75 caliber) shells with enormous stopping power. They can range from full-size long arms to smaller handguns as shown here, and fire a wide range of ammunition. Normally only Space Marines or Sisters of Battle can wield them with the aid of their power armor; however, smaller caliber versions can be custom-made for normal humans. (They are often seen as a status symbol, hence their popularity with Commissars, officers, and high-ranking officials.)