Master Gunsmith hex head screw kit 140-piece - Pachmayr
A scope mount is only as strong as the smallest screw holding it together. And those are exactly the screws that go missing, strip out or turn out a fraction too short when you fit a new base. Loose screws in the right thread and length are hard to find in Europe. With this Pachmayr kit, they are simply sitting in your drawer.
The kit holds 140 screws with a 3/32" hex head, roughly 2.4 mm. You get ten of each of 14 sizes, and every screw takes the same key size, so one hex key or bit covers the lot.
Why hex instead of slotted
Plenty of older bases and rings are held on with slotted screws. They work, but a screwdriver easily jumps out of the slot under load. That chews up the screw head, the base or, worst case, the finish on your receiver. A hex head gives the key far more grip, so you can bring the screw up to torque under control. That is why these screws are such a popular replacement for slotted ones.
What is in the kit
The kit covers the three threads you run into most on scope bases and rings. #6-48 is the standard base screw thread on many American receivers, while #8-40 shows up on heavier bases and on receivers drilled and tapped for it. Each thread comes in both a fillister head and an oval head, in several lengths:
#6-40 fillister head: 3/8" and 1/2"
#6-40 oval head: 1/4" and 3/8"
#6-48 fillister head: 1/4", 3/8" and 9/16"
#6-48 oval head: 1/4" and 3/8"
#8-40 fillister head: 1/4", 3/8" and 1/2"
#8-40 oval head: 1/4" and 1/2"
For reference, 1/4" is about 6.4 mm, 3/8" about 9.5 mm, 1/2" about 12.7 mm and 9/16" about 14.3 mm.
Thread gauge and shortening jig
The kit comes with a thread gauge, so you can quickly identify the thread of a screw or hole. Handy when you are fitting a base that arrived without paperwork. The same gauge doubles as a jig for shortening a screw: thread the screw in and grind off the excess to the length you need. That matters, because a base screw that is too long can protrude inside the receiver. Always check the length before you tighten a screw down.
Practical use
Always tighten mount screws to the torque specified by the maker of your base or rings. A torque driver such as the Wheeler FAT Wrench stops you going too tight or too loose. Clean and degrease the threads in the receiver before fitting a new screw. If you use a threadlocker, choose a medium strength one so the screw can still come out later.
The tweezers make it easy to pick small screws out of their compartments and start them in a tight mount. Individual screws are not sold separately, only the complete kit.
Specifications
Type: screw kit for scope bases and rings
Brand: Pachmayr (Lyman Products)
Article number: 03058
EAN: 034337030584
Contents: 140 screws, 10 each of 14 sizes
Key size: 3/32" hex (approx. 2.4 mm)
Threads: #6-40, #6-48, #8-40
Head types: fillister and oval
Lengths: 1/4", 3/8", 1/2" and 9/16", depending on thread and head
Included: storage box with a compartment per size, tweezers, thread gauge/shortening jig
Use: replacing and stocking screws for scope bases and rings
Not sure which thread or length your base needs? Email us at vragen@hop.nl, we work on our own rifles and are happy to think along. You can also browse our other firearm tools for the full range.
