Roofing Nailer Replacement Parts
Coil roofing nailers are simple machines with a few well-known wear points: o-rings, trigger valve, driver blade, piston bumper. Most "broken" guns are a $20 rebuild kit away from running like new. Below: every replacement part we stock, with the OEM part numbers and replacement intervals to plan a rebuild before the gun quits mid-roof.
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Common roofing nailer wear parts and replacement intervals
| Model | Function | Replace Every | Common Symptom | Fits |
|---|---|---|---|---|
| O-ring rebuild kit | Seal piston & cylinder | 5,000–10,000 shots | Air leaks from cap | RN46-RK: Bostitch RN46/RN46-1 |
| Trigger valve assembly | Controls firing | 10,000–20,000 shots | Gun won't fire / leaks at trigger | Bostitch TVA6 & equivalents |
| Driver blade | Drives the nail | 50,000–100,000 shots | Nails not flush, mushrooming | All major coil roofers |
| Piston bumper | Absorbs piston impact | 20,000–50,000 shots | Loud bang, hard recoil | Bostitch 191777 & equivalents |
| Magazine pawl / feeder | Advances the coil | 20,000–50,000 shots | Skipped nails, double-feed | Model-specific |
| Wear pad / canister | Protects canister | 10,000–30,000 shots | Visible wear, jam frequency up | Bostitch 149866 & equivalents |
| Nose / no-mar tip | Prevents shingle scuff | As needed | Visible scuffing on shingles | All models — slip-on |
| Air fitting / hose swivel | Hose connection | As needed | Hose drag, leak at fitting | Universal 1/4" NPT |
Replacement intervals are typical — duty cycle, lubrication and air quality all change real-world life. Sources: manufacturer service manuals, Bostitch RN46 service bulletin, MAX CN445R3 maintenance guide.
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Match the gun to the work — these are the picks pros reach for in each scenario.
Gun leaks from the cap
Air hisses around the top.
Cap leaks are almost always a top o-ring — $15 fix.
Gun won't fire
Air on, trigger pulls, nothing.
Trigger valve is the second most common failure after o-rings.
Nails not driving flush
Heads sit proud or mushroom.
Worn driver tip dulls the strike — flush-drive returns instantly with a new blade.
Loud bang on every shot
Recoil feels harsh.
Worn bumper = piston bottoming on metal. New bumper restores cushion.
Bostitch RN46 specifically
America's most-sold roofer.
Single kit covers o-rings, bumper and seals.
Nose scuffing shingles
Black marks on architecturals.
Slip-on rubber tip — under $5, saves a callback.
How to diagnose and rebuild a roofing nailer instead of replacing it
Most 'broken' guns just need o-rings
If your nailer is leaking air, hesitating, or losing power, the cause is almost always a tired o-ring. The cylinder o-rings dry out from heat and pressure cycles. A $15 rebuild kit (Bostitch sells the RN46-RK) restores factory firing power in under 30 minutes on the bench.
Air leak at the cap = top o-ring. Air leak at the trigger = trigger valve o-ring. Air leak from the nose = bumper or main piston seal.
Driver blades and bumpers — the second rebuild
After roughly 50,000 shots, the driver blade tip dulls and you'll notice nails sitting proud or heads mushrooming. New blade = instant flush-drive. The piston bumper usually goes around the same time — symptom is a louder bang and harder recoil. Replace them together while the gun is apart.
When to rebuild vs replace the gun
If the cylinder is scored or the magazine housing is cracked, replace the gun. Everything else is a part. Bostitch, Metabo HPT and MAX all publish full exploded-view diagrams — match the part number to the diagram before ordering. Read our Bostitch parts guide for the most-replaced RN46 components.
Frequently asked questions
Related guides & reviews
Bostitch roofing nail gun parts
RN46 part numbers and full rebuild walkthrough.
Read guide →Roofing nail gun not firing
Diagnosis flowchart by symptom — driver vs trigger vs feed.
Read guide →Roofing nail gun troubleshooting
Every common symptom mapped to the likely failed part.
Read guide →Roofing nail depth adjustment
When the depth dial fixes what feels like a part failure.
Read guide →How to load a coil roofing nailer
Loading mistakes that look like magazine-part failures.
Read guide →Bostitch roofing nail gun overview
Anatomy of the most-rebuilt roofing nailer on the market.
Read guide →