GUN is a hinge word: 2 words make a compound in front of it and 6 make one after it, so it can sit in the middle of a chain and hold two compounds together at once.
Each of these makes a compound ending in GUN.
Each of these makes a compound starting with GUN.
GUN is a short, vivid noun with a lot of company. SHOTGUN and HANDGUN name kinds of gun; GUNFIRE, GUNSHOT and GUNPOWDER name what a gun produces or needs. GUN and SHOT famously join in both orders.
These words make a compound whichever side of GUN they sit on, usually with two unrelated meanings.
Put any word from the first list in front and any word from the second behind, and you have a three-word chain in which both neighbouring pairs join. Here are some of them.
HAND → GUN → FIRE — handgun and gunfireSHOT → GUN → MAN — shotgun and gunmanKEYSTONE is a free daily puzzle built entirely out of chains like these. You get the two ends and have to fill the two words in the middle. Three bridges a day, no account, no cookies.
Each of these has a page like this one. There is also an index of all 28.
BACK · BALL · BED · BOARD · BOOK · BREAK · DAY · DOWN · FALL · FIRE · HAND · HEAD · HOUSE · LAND · LIFE · LIGHT · MAN · NIGHT · OFF · OUT · OVER · SHIP · SIDE · SOME · TIME · WAY · WORK