A Tinkerer’s Guide to The Barra 1100z Trigger
Before we proceed to tuning the gun – yes, I know that always means increasing the power – let’s first take a look at the Barra 1100z trigger.
Once the stock is removed, the Barra 1100z trigger is found to be a version of the long-running QB78/Crosman 160 trigger.
That means that it was first designed waaaaay back in 1955 in Fairport NY and since has been reproduced and – maybe – improved through use in the QB78 and, now, the Barra 1100z.
So we know that this basic trigger is reliable and simple. Yet it can also be set to provide a really quite good trigger experience.
As I’m convinced that this air rifle will become the “go to” model for many owners who want to learn about, and understand, air rifles, this seems a good time to look at the trigger, how it works and how to adjust it.
Before we go any further, I have to issue a safety warning. As with any airgun tinkering, you MUST ensure that the gun has no pellet in the barrel and has no pressure in the HPA tube before making any adjustments. Proceed at your own risk!
The trigger blade itself is pivoted to provide the effect of a two-stage trigger. But basically this is a single-stage trigger mechanism we’re dealing with.
The first step in tinkering with the Barra 1100z trigger is to remove the stock.
To do this, first set the safety to “safe”. Then drive it out from the “non lever” side using a non-marring punch. (I’ve always used a brass punch for this purpose).
You’ll immediately see the two socket head screws in the underside of the gun. You’ll need a 4mm Allen (hex) wrench to remove the front one. A 5mm wrench will allow the rear one to be removed.
With the action out of the stock, the trigger assembly becomes visible. It’s actually a “box” assembly containing the individual parts, as we can see below. There’s a side plate on the right side of the trigger box. However, before we remove the screws and take off the plate, let’s take a look through that hole.
The hole in the trigger side plate allows you to see the sear engagement. It’s a very useful feature that can allow the sear adjustment to be adjusted with the side plate in place.
However, we’ll remove the side plate to see the parts of the trigger. As you can see, it’s quite simple…
The plunger and spring identified by the “4” below is the safety mechanism.
The safety lever pushes this up, when engaged and prevents the trigger from operating. We’ll ignore it for our trigger adjustment discussions and – really – there’s no reason to mess with it at all.
The Barra 1100z trigger can be adjusted using three screws, These pass through the rear of the trigger box and are readily visible in the photographs above and below.
Screws 1 and 2 are adjusted using a 1.5mm Allen (hex) wrench. Screw 3 is adjusted using a common flat-head screwdriver.
Screw 1 adjusts the sear engagement. This engagement is set by the factory and – unless there is a problem with the trigger, I recommend leaving it alone.
Screw 2 sets the over-travel. I’ve never seen this screw correctly set by the factory on a QB78-type trigger in 15 years – and it’s not on the Barra 1100z!
Basically, screw 2 can be rotated clockwise to gently engage with the rear of the trigger blade assembly. When correctly adjusted, it prevents over-travel after the shot has been released, a very satisfactory feeling for the shooter.
If set incorrectly, the trigger will not release. In that case, back off a little!
Screw 3 controls the trigger pull weight. Adjusting counter-clockwise reduces the trigger pull weight.
Typically the pull weight for this type of trigger is in the region of 2 Lbs. The gun tested by HAM had a pull weight of just below this.
It’s easy to adjust the pull weight, simply by rotating the adjustment screw. But – if you choose to reduce the trigger pull weight – you MUST check to ensure that the pull weight set is not too light. This is possible!
To check for safety, I cock the (unloaded and de-pressurized) action and bang it down breech-first onto a carpeted floor. If the gun does not fire it’s safe. if it goes “bang” you need to increase the trigger pull weight. MAKE THAT CORRECTION!
Hopefully this has given you some insight into the Barra 1100z trigger. Next, we’ll move on to adjusting the hammer spring adjustment to see what power improvements are possible!