How a Faulty Receiver Can Ruin Your Trigger

By Kevin Muramatsu

Incorrect Distance Between Trigger Pin Holes

The sear and hammer interface in the fire control group is designed to have 100% lateral contact. If the interface area is .200” wide, then there should be contact along that entire .200” width. If the pin holes (and therefore the trigger and hammer pins) are not parallel with each other, this contact is reduced.

This might actually lower the trigger pull weight slightly and feel like a really crisp trigger, but it is not ideal. There is actually a higher likelihood of the engagement breaking accidentally. This might occur when you drop your rifle from a deer stand or trip and fall running through a rifle string.

Fortunately, this is uncommon. Even when it is present, the deviation is usually quite minor. The clearance play between the trigger and hammer is typically sufficient to negate the problem of a crooked, insubstantial interface.

Evidence of bad fit like this will eventually show on the hammer itself. You will see clearly defined wear on the sear notch that does not cover the entire engagement surface. Just realize that it may take a considerable round count before exhibiting this wear.

If the holes are off enough, it can cause binding symptoms in the fire control group. Unfortunately, there is little to nothing that can be done to repair such receivers. If you have a receiver with grossly non-parallel pin holes, better to return it and get a new one under warranty if possible.