The gun is the part you hold, and on most consumer machines it is also the part made of the cheapest plastic. It is usually fine for two or three seasons and then starts weeping at the trigger or the inlet. That is the moment to replace it, not before.
Three reasons to replace one
It leaks. A weep at the trigger means the internal seal has gone. It is not repairable on a consumer gun and it will get worse.
The trigger is uncomfortable. Stock triggers are often stiff and narrow-faced, which is genuinely tiring over a long job. A better gun is a real quality-of-life upgrade if you use the machine a lot.
You want a swivel inlet. This is the best reason. A swivel at the hose connection lets the gun rotate without twisting the hose, which stops the hose coiling into loops behind you — the single most irritating thing about using a pressure washer. You can also add a separate swivel fitting to a gun you already own for a few dollars, which is the cheaper route.
The one spec that matters
The pressure rating, and the only thing you need is for it to comfortably exceed your machine. A gun rated 4,000 or 5,000 PSI on a 2,000 PSI machine is not overkill — it means the gun is no longer the weak link, and at these prices the higher-rated ones cost nothing extra.
Beyond that, prefer brass or stainless internals over plated zinc. On the part you hold, under pressure, in water, every day you use it.
Get the fittings right before you order
A gun has two connections and they can differ. The inlet (hose side) is usually M22 threaded on homeowner machines, sometimes 3/8-inch quick connect. The outlet (wand side) is usually 1/4-inch quick connect.
And M22 comes in 14mm and 15mm variants that look identical and will not seal against each other. This is the most common cause of a one-star review on a perfectly good gun. A cheap adapter set covers every combination — buy one at the same time, and read the quick connect guide before ordering.
Gun-plus-cannon bundles
Several replacement guns ship with a foam cannon attached, which is good value if you wanted both. The caveat is the usual one: a bundled cannon is not as good as a dedicated one, and foam quality depends mostly on your machine’s flow rather than the cannon. If foam is the point, read best foam cannons first.
What I left out
Guns with built-in pressure dials. They work by restricting flow, which is a worse way to reduce force than changing nozzle or stepping back, and they add a failure point.
Unrated budget guns. A gun with no stated pressure rating, in your hand, under pressure, is not where to save three dollars.
If your gun is fine and your hose is the problem, that is how to choose a pressure washer hose.
