The JK Armament 155 Piston in .578×28 is the booster piston that screws onto a threaded .45 ACP pistol barrel and mates the pistol to a suppressor (JK Armament part no. JK155PISTON578X28). JK Armament machines it from 17-4 PH stainless steel, and its job is to isolate the suppressor from the moving barrel so a short recoil-operated pistol keeps cycling reliably. On the suppressor side it threads into the base of a JK 155 tube using the HUB-standard 1.375×24 thread, installing in place of the taper mount or other mount accessory. That same HUB thread also suits other suppressors that carry it and have enough internal length for the booster housing. It is a compact way to run a pistol suppressor on a .45 ACP or other larger-than-9mm barrel with this thread.

Key Specifications

• The barrel-side thread is .578×28, the pattern JK lists for .45 ACP and some other larger-than-9mm pistol calibers.
• The housing material is 17-4 PH stainless steel, a precipitation-hardening alloy suited to repeated recoil loading.
• The suppressor-side thread is HUB 1.375×24, the industry standard that fits JK 155 tubes and many other HUB-threaded suppressors.
• The booster housing needs about 1.8 inches of internal suppressor length, so confirm that a non-JK suppressor has the room.
• It works as a booster piston that isolates the suppressor from the moving barrel, which lets short recoil-operated pistols keep cycling.
• It installs in place of the taper mount or other mount accessory on a JK 155 suppressor rather than stacking on top of it.

Frequently Asked Questions

Which pistol barrels use the .578×28 thread? JK lists .578×28 for .45 ACP and some other larger-than-9mm pistol calibers. JK also makes a 1/2×28 piston for nearly all 9mm pistols, so check the thread on your own barrel before you order.

Which suppressors does this piston fit? It threads into the base of a JK 155 suppressor tube, and it works with any other suppressor that has HUB 1.375×24 threads and about 1.8 inches of internal length for the booster housing.

Do I need a piston mount too? Yes. The JK Piston pairs with the JK Piston Mount, and this listing is the piston for shooters who already own that mount. JK sells a separate bundle that includes both.

Buy the JK Armament 155 Piston, .578×28 for .45 Cal Pistols

The piston is the one part that has to match your barrel exactly, and this one is cut for .578×28 pistol threads with the HUB standard on the suppressor side. Order it with the rest of our Class 3 parts and accessories from our Lubbock, Texas gun shop for fast direct shipping.