Proper Allen or Hex Head Screw Tightening

Something I see at the shop quite often is rounded out Hex head screws. Customers will return scope mounts claiming they received defective screws. We use only screws made in the USA to strict Allen manufacturers product specifications. We are a VERY small shop and I personally examine every return we receive. We have a very minute rate of return and generally the returns are screw related.

I use a 10X loop (magnifying glass) to look inside of the hex cavity to determine why the hex failed. The overwhelming reason for failure is installers do not get the Allen wrench inserted in all the way to the bottom of the cavity. When you look into the ruined screw cavity you will see it is rounded out only half the way down with the lower portion of the hex intact. The smaller the key size the more sensitive the screws are to rounding out. When inserting the key take your time and make sure the key bottoms out in the bottom of the cavity. The key then has a full purchase on the entire hex pocket and generally will never round out. Even over tightening the screws will not round them out if you bottom the key in the cavity.

The second biggest problem is cheap hex keys. You will find in our instructions we suggest using only Allen brand keys. In good USA made screws an Allen brand key will fit very snug. The off brand made in China hex keys are generally loose fitting and have a way better chance of rounding out the screw cavity.

In 30+ years of installing our mounts I have never once rounded out and Allen screw during installation. Sometimes removing a thread locked screw can be a different story but that is for another post.

The key to successfully installing a Allen or hex head screw is

1)     Use only Allen brand hex keys. You can find them HERE, at the bottom of the page, on our web site

2)     Always bottom the key in the hex cavity in the screw.

You can view our entire line of scope mounts the the following link

Weigand Scope Mounts