Nothing that goes into a salt marsh is immune, but the differences are large. Stainless steels and anodised aluminium resist salt far better than plated carbon steel, and polymer does not corrode at all, though it wears and gets brittle in the cold. The failure most people never see coming on waterfowl sling hardware is galvanic: two dissimilar metals touching in salty water, with one of them dissolving to protect the other.
Webbing matters as much as metal, because whatever stays soaked against a fitting decides how long that fitting lasts. This is about mechanisms rather than brands, so you can look at any sling and work out where it will fail first.
Why salt marsh is harder than fresh water
Corrosion in water is electrochemical. It needs an anode where metal dissolves, a cathode where a matching reaction happens, an electrical path between them and an electrolyte to carry ions. Fresh water is a poor electrolyte. Salt water is an excellent one, because dissolved chloride carries current readily. That is why a fitting that lives for years on a duck pond can look tired after one season on a brackish tidal creek.
Chloride does something worse than conduct. Stainless steel and aluminium both rely on a thin, self-healing oxide film to stop the metal underneath reacting. Chloride attacks that film locally, which is why salt exposure on those metals tends to show up as pitting rather than an even rusty haze: the film fails at one small spot and attack concentrates there while the surface around it stays bright.
Wet and dry cycling makes it worse. A fitting that is splashed and then dries in the wind does not end up clean. The water goes, the salt stays, and the next dew redissolves it at a higher concentration than the water you were standing in. Gear that gets rinsed and dried is fine. Gear that gets splashed and dried is worse off than gear that stayed wet.
So do crevices. Anywhere two surfaces are pressed together with a thin gap, the trapped water becomes chemically different from the water outside: oxygen is used up and cannot easily be replaced, and the trapped fluid turns more aggressive. That is crevice corrosion, and sling hardware is full of crevices. Under a swivel base, inside a socket, between a screw head and its seat, in the fold of webbing wrapped around a bar.
Steel, stainless, aluminium and polymer
Carbon steel
Strong, cheap and it rusts. Bare steel in salt water forms an oxide that flakes away rather than sealing the surface, so the reaction keeps going into fresh metal underneath instead of stopping. Steel hardware is therefore only as corrosion resistant as whatever is on top of it. Where it earns its place is in parts needing real strength in a small cross section, like springs and pins.
Stainless steel
Stainless is a family, not a material, and its members behave very differently in salt. What they share is enough chromium to form a passive oxide film that repairs itself in the presence of oxygen. In a marsh two things break that promise: chloride attacking the film, and crevices where the oxygen needed to rebuild it cannot get in. Stainless is a large improvement over plated steel, not a guarantee, and a part that looks clean on its outer face can be corroding underneath where it clamps down.
Aluminium
Aluminium also relies on a passive oxide film and forms one almost instantly. Anodising deepens that film deliberately, converting the surface into a thicker, harder oxide rather than adding a separate coating on top. That distinction matters: an anodised surface is part of the metal, so it does not chip off the way paint does, but it can be worn through by abrasion and undercut by chloride pitting. Aluminium’s real weakness here is not its own resistance, which is decent. It is where aluminium sits relative to other metals.
Polymer
Polymer does not corrode. There is no electrochemical reaction to have, so no rust, no pitting and no galvanic pairing. That is a genuine advantage and it is why polymer shows up in buckles and adjusters on gear built for water. What polymer does instead is wear, creep and go brittle. Grit grinds material away at contact points, sustained load slowly deforms a part, and sunlight degrades some polymers over years. Cold matters more than people expect: many polymers get markedly less tough as temperature drops, so a hard knock against a boat gunwale on a freezing morning is a different test from the same knock in September.
| Material | Corrosion behaviour | Fails by | Watch for |
|---|---|---|---|
| Carbon steel, plated | Only as good as the plating. Base metal rusts freely once exposed | Rust spreading under and around a breach in the coating | Orange staining at edges, screw heads and stamped corners |
| Stainless steel | Passive film resists salt but is attacked by chloride | Pitting and crevice corrosion in shielded, oxygen-starved spots | Small dark pits, staining under a base plate or inside a socket |
| Aluminium, anodised | Hard oxide surface that is part of the metal, not a film on top | Pitting, and galvanic attack when coupled to a more noble metal | White powder, chalky bloom, dull patches where anodising wore through |
| Polymer | Does not corrode at all | Abrasion, creep under load, sunlight ageing, brittleness in cold | Rounded-off edges, whitened stress lines, loose adjuster grip |
| Mixed metals in contact | Behaviour is set by the pair, not by either metal alone | Galvanic corrosion of the less noble part | Corrosion concentrated exactly where two different metals touch |
Scroll the table sideways to see every column.
Coatings, platings and what a scratch does
Surface treatments fall into two groups that behave in opposite ways once damaged, and knowing which one you have tells you how worried to be about a scratch.
Barrier coatings keep water off the metal. Paint, powder coat and most ceramic-style firearm finishes are barriers. They work while intact, and a scratch through to bare steel is a real problem: the exposed spot is now a small anode surrounded by a large protected area, so corrosion concentrates there instead of spreading thinly. That is why a chipped painted fitting can develop a bloom of rust creeping under the coating from one small nick.
Sacrificial coatings corrode instead of the base metal. Zinc plating and galvanising are the classic examples. Zinc is less noble than steel, so where the coating is scratched the surrounding zinc preferentially corrodes and protects the exposed steel for a while. That tolerance is real but finite, and thin decorative plating on a small fitting does not have much material to give.
Conversion treatments sit slightly apart. Anodising on aluminium and phosphate on steel change the surface chemistry rather than laying something on top, so they do not chip, but they are thin and can be abraded away or penetrated by pitting.
Assume every coating on a hunting sling will eventually be scratched, because gear rubs against boats, blinds, decoy bags and gun barrels. Choose hardware that is acceptable when the coating is gone, not hardware that is only acceptable while it is perfect.
Galvanic corrosion, the one people miss
This is the mechanism worth understanding properly, because it explains failures that look inexplicable otherwise: a good quality fitting corroding badly while an apparently cheaper part beside it is fine.
When two different metals are in electrical contact and both are wetted by the same electrolyte, they form a cell. The less noble metal becomes the anode and dissolves faster than it would alone. The more noble one becomes the cathode and is actually protected. Salt water, being a strong electrolyte, makes this happen readily. Three things set how bad it gets.
How far apart the metals are in nobility. The bigger the gap, the stronger the drive. Aluminium paired with stainless steel is a wide gap. Aluminium paired with aluminium is no gap at all.
The area ratio, and this is the one that catches people. A small anode connected to a large cathode is the worst arrangement, because all the corrosion current concentrates into a small piece of metal. A small aluminium part clamped by a large stainless one suffers far more than the same two metals in the reverse proportion. It is why a fastener in the wrong metal can destroy itself quickly while the big part it holds looks untouched.
Whether there is an electrolyte, and for how long. Dry, no cell. Continuously wet with salt water, a very active cell. Damp webbing wrapped around a metal bar, holding brine against the joint for the whole drive home, is much closer to the second case.
The fixes follow directly. Prefer matched metals where parts clamp together, because if a swivel body, its pin and its screw are in the same family there is no cell to drive. Where you cannot match, isolate: a polymer washer or bushing between two dissimilar metals breaks the electrical path, which is exactly why polymer parts in an otherwise metal assembly are sometimes a design feature rather than a cost saving. Check the small parts first, since screws, pins, detent balls and springs are the small anodes in most assemblies. And break the electrolyte, because rinsing removes the one ingredient the cell cannot run without.
Confirm the firearm is unloaded before removing, refitting, cleaning or inspecting a sling, a swivel or a mount. Check the magazine and the chamber, look and feel, and keep the muzzle in a safe direction throughout. Do this every time, including at the truck at the end of a cold morning when you are in a hurry.
Webbing choice matters as much as metal
Corrosion needs water sitting on metal, and the biggest reservoir of water anywhere near your hardware is the webbing wrapped around it. Fibre choice therefore changes the corrosion story, not just the comfort one.
Nylon is strong and abrasion resistant, and it absorbs a meaningful amount of water into the fibre itself. Wet nylon holds that water, swells slightly, and loses some strength while saturated, recovering as it dries. It is also slow to dry, which means the webbing at the fitting stays a damp salt sponge long after the hunt. Polyester absorbs very little water by comparison, dries faster, holds its strength when wet and stands up to sunlight better.
Nylon webbing
- Excellent abrasion resistance and toughness
- Some stretch, which softens shock loads
- Absorbs water into the fibre and holds it
- Slow to dry, so it stays wet against metal
- Loses some strength while saturated
Polyester webbing
- Very low water absorption
- Dries considerably faster
- Holds strength when wet
- Better resistance to sunlight over years
- Less stretch, which is a preference rather than a fault
Beyond fibre, look at construction. Padding, neoprene shoulder pieces and any foam layer hold water long after the strap itself feels dry, and if that pad sits over a metal component you have built a poultice. Stitched loops that trap webbing tightly against a bar hold brine in the fold. Anything that lets water drain and air circulate is doing corrosion work for you. A sling built with maritime grade webbing and all metal hardware is designed around this environment rather than around a dry range, which is the distinction that starts to matter once the gun goes in a boat.
Swivels, sockets and grit
Marsh mud is not just wet, it is abrasive. Fine sand and silt find their way into every recess and do two things.
First, they jam moving parts. A quick detach swivel works on small spring-loaded balls or a plunger seating into a groove. Pack that with grit and the plunger stops travelling fully, which either means the swivel will not release or, much worse, it does not lock fully and can release under load. Push and pull test every attachment point every time you fit it, particularly after a muddy session.
Second, grit continuously abrades away the passive film and any coating from the surfaces it grinds against. Metal that could otherwise repassivate is being scoured back to bare, in a place that is wet and salty. Abrasion plus corrosion is far more destructive than either alone. Rotating swivels add the problem of a bearing surface you cannot see, which is exactly the oxygen-starved crevice described earlier. If a swivel starts to feel gritty or notchy when it turns, that is information. Our guide to the shotgun sling swivel covers the types and how they attach, and the quick detach sling mounts category shows the mounting side of that joint.
A realistic post-hunt routine
Realistic means it survives being done at the end of a cold, dark morning when you are tired. Anything elaborate will not happen twice.
- Confirm the gun is unloaded
Magazine and chamber, look and feel, action open, muzzle safe. Do this before the sling comes off, not after.
- Take the sling off the gun
You cannot rinse a joint properly with the strap clamped over it, or dry webbing that is folded around a bar. Detaching also lets you clean the gun properly, which is its own job, covered in how to clean a shotgun.
- Rinse with plain fresh water
The point is dilution, not scrubbing. Run water through swivel bodies, sockets and any recess where salt can hide, and flush the webbing where it wraps hardware. This is the single highest-value step in the list.
- Flush grit out before it dries
Work quick detach plungers and swivel joints under running water so the mechanism cycles and pushes silt out. Dried mud in a detent is far harder to shift than wet mud.
- Dry thoroughly, including the hidden parts
Towel what you can reach, then hang the sling somewhere with moving air, unfolded and not coiled. Open any padding out flat. Warm is fine, hot is not: keep it away from direct heat that can damage webbing and stitching.
- Lightly oil the steel
A thin film of a corrosion-inhibiting oil on steel components displaces water and slows the reaction. Keep it off the webbing, where it attracts grit and does nothing useful.
- Inspect while it is in your hands
This is the moment you will actually look at it, so use it. Ten seconds against the checklist below is enough.
If you do nothing else, rinse in fresh water and dry properly before storage. Corrosion needs an electrolyte, and salt left on the metal in a warm truck or a closed case keeps working for days after you stopped hunting. Storage, not the hunt, is where a lot of the damage happens.
When to retire a part
Cosmetic damage and structural damage look different. Learn the difference and you will stop worrying about the first and stop ignoring the second.
- Surface staining on stainless is usually cosmetic and can often be cleaned off, but it tells you salt is sitting there.
- Distinct pits are not cosmetic. A pit is a hole going into the metal and its depth is invisible from outside. On a small load-bearing part, treat pitting as a reason to replace it.
- White chalky powder on aluminium is corrosion product. A light bloom is common. Concentrated in one spot, especially right where the aluminium meets a different metal, that is the galvanic signature.
- Rust creeping out from under a coating means the base metal is corroding somewhere you cannot see or clean. The visible spot is smaller than the real one.
- A spring or detent that does not snap back is a functional failure, not a maintenance item. Any attachment point that will not lock positively goes out of service immediately.
- Frayed webbing or broken stitching at a fitting means the fitting has been abrading the strap. Replace it and work out what was rubbing.
- Play that was not there before means material has been removed by wear or corrosion, and load is now carried by a smaller cross section.
A sling is a load path with your firearm hanging off it, over water and often over a boat. It is not a component to nurse past its useful life. If any part of the chain looks doubtful, replace that part.
For setting a sling up for waterfowl carry, including carry positions in a boat and in a blind, see our guide to the duck hunting shotgun sling and the fitting steps in how to put a sling on a shotgun. If the same gun shoots clays in the off season, our piece on whether you need a sling for clay shooting covers a very different set of trade-offs.
Frequently asked questions
Is stainless steel sling hardware rustproof in salt water?
No. Stainless resists salt far better than plated carbon steel, but chloride attacks the passive film that makes it stainless, so it can pit and it can suffer crevice corrosion in shielded spots where oxygen cannot reach. It is a large improvement, not an exemption from rinsing.
Why is my aluminium fitting corroding where it touches a steel part?
That is galvanic corrosion. Two dissimilar metals in electrical contact, both wetted by salt water, form a cell in which the less noble metal dissolves faster. Aluminium is less noble than stainless steel, so the aluminium goes first, and it goes fastest when the aluminium part is small relative to the steel one. Matched metals or a polymer isolator between them prevents it.
Nylon or polyester webbing for waterfowl hunting?
Polyester absorbs much less water, dries faster and keeps its strength when wet, which also means it spends less time holding brine against your hardware. Nylon is tougher against abrasion and has some useful stretch. For a strap that will be repeatedly soaked in salt water, low water uptake is the more valuable property.
Does freshwater rinsing really make a difference?
It is the highest-value thing you can do. Corrosion here is driven by chloride in an electrolyte, and rinsing dilutes and removes it. Drying afterwards matters just as much, because salt left in a closed case keeps working long after the hunt is over.
