Maxim Defense PDW Buffer Spring Kit for Daniel Defense

Product Description

The Maxim Defense PDW Buffer Spring Kit for Daniel Defense is a two-spring replacement kit for the Maxim Defense CQB Pistol Brace or CQB Gen 7 Stock – the recoil units found on the Daniel Defense PDW pistol and PDW short-barrelled rifle – and it lets you match spring rate to how the gun is being shot.

A compact PDW-style recoil system has very little travel to work with, so spring rate matters far more than in a full-length carbine tube. Run the gun unsuppressed with subsonic ammunition and there is barely enough energy to cycle; add a suppressor and the back pressure swings the problem the other way. One spring cannot cover both ends of that range.

The selection rule is simple. Red is for unsuppressed fire with subsonic ammunition. Silver – the standard spring – is for unsuppressed fire with supersonic ammo, or for suppressed fire with either subsonic or supersonic ammo. Label them and keep the one that is not in the gun with your spares.

Key Facts

• Model: Maxim Defense PDW Buffer Spring Kit
• Manufacturer Part Number / SKU: 28-102-00189
• Kit contents: two replacement springs – one red, one silver / standard
• Red spring: for unsuppressed fire with subsonic ammunition
• Silver / standard spring: for unsuppressed fire with supersonic ammo, or suppressed fire with either subsonic or supersonic ammo
• Fitment: Maxim Defense CQB Pistol Brace or CQB Gen 7 Stock, as featured on the Daniel Defense PDW pistol (brace) and PDW short-barrelled rifle (stock)

Matching the spring to how you shoot

Work out your normal configuration first. A PDW with a suppressor on the front and subsonic ammunition in the magazine wants the silver spring; the same gun on a bare muzzle with subsonic loads wants the red one. Changing ammunition without changing the spring is what produces a PDW that fails to lock back. Related parts sit in our buffers and buffer tube kits and stocks and stock accessories sections, with the rest of the line under Daniel Defense products.

Ordering from Western Sport in Roanoke, TX

A Daniel Defense master dealer with an FFL/SOT in Roanoke, Texas since 2007, Western Sport can order PDW parts directly. This kit is on backorder; call 817-393-4000 and we will place it. Our on-site gunsmith knows the CQB unit and can swap the spring for you if you would rather not pull the stock apart.

Frequently Asked Questions

Q: Which of the two springs do I use?

A: Use the red spring when running the Daniel Defense PDW unsuppressed with subsonic ammunition. Use the silver, standard spring for unsuppressed fire with supersonic ammo, or for suppressed fire with either subsonic or supersonic ammo. That single rule covers every combination the kit is built for.

Q: What does it fit?

A: It is designed to work with the Maxim Defense CQB Pistol Brace or the CQB Gen 7 Stock – the units featured on the Daniel Defense PDW pistol and the PDW short-barrelled rifle respectively. It is not a spring kit for a standard mil-spec carbine receiver extension.

Q: Why does a suppressor change which spring I want?

A: A suppressor raises back pressure, which drives the carrier harder and faster. Subsonic ammunition run unsuppressed does the opposite: less gas, less energy, so the system needs a lighter spring to cycle at all. The kit exists because those two extremes cannot share one spring rate.

Q: Can I fit these springs to a normal carbine buffer tube?

A: No. These are replacement springs for the Maxim Defense CQB brace or stock, which uses its own compact recoil system rather than a mil-spec carbine tube and spring. If you are looking for a standard carbine buffer spring, call 817-393-4000 and we will point you at the right part.

Q: Do I need this kit if I only shoot supersonic ammunition unsuppressed?

A: Your gun already uses the silver, standard spring for that, so a kit is a spare rather than a fix. It becomes worth having the moment you add a suppressor or start shooting subsonic loads, because then you have a reason to change springs and something to change back to.

Q: Is swapping the spring a gunsmith job?

A: It is a user-level task on the Maxim CQB unit, but the assembly is compact and under tension, so read the instructions for your brace or stock before you start. If you would rather not disassemble a spring-loaded stock on the kitchen table, our gunsmith in Roanoke can do it.

Additional information