Garand Thumb tests a progressive trigger for the PS90

The FN PS90 has long been the civilian, semi-auto-only cousin of the P90. A small company called FN Specialties now sells a progressive trigger pack for it, and Garand Thumb brought its designers to the range to see how it runs.

The short version

Garand Thumb opens with a short-barreled PS90 and walks through what makes the design unusual: a direct-blowback bullpup that ejects downward and feeds from a long translucent magazine running along the top. Then he shows the upgrade. The FN Specialties trigger pack uses a three-position selector, and in the fast position the trigger works progressively: a partial pull fires a single shot, and pulling through the break runs the gun much faster. He compares the feel to the progressive trigger on a Steyr AUG.

The company's engineers say the design took about eight months and many iterations to get the internal geometry right. Garand Thumb and the company's shooter run one-handed strings, reloads, timed drills and a long single shot at about 90 yards before switching to rapid fire on closer targets. Their consistent remark is how controllable the light 5.7mm gun stays.

Key points

• How it works: In the fast position, a half pull gives one shot and a full pull keeps the gun running, so the shooter does not need to change the selector.
• Durability: The company says it has put about 8,000 rounds through testing, with hammer-pack parts milled from billet 17-4 stainless, heat treated and nitrided.
• Availability: The designers say it can be owned in most states, with some exceptions.
• Heat: Because the barrel is enclosed in the bullpup receiver, they suggest letting it cool after roughly 100 to 150 rounds of fast shooting.
• Maintenance: Keep the bolt assembly and hammer pack clean and lubricated, and clean weekly with daily use.

Bottom line

For PS90 owners who want the gun to run closer to how it was designed, this is a look at one aftermarket answer from the people who built it. Check your state's rules on trigger devices before buying, and treat the durability figures as the maker's own.

Source: Garand Thumb