Bront's Blowback Guide
Blowback markers are the most common type of semi-auto starter marker on the market today.
This is mostly due to how cheap it is to make, as well as maintain. This here is a guide
about the workings of a stacked tube blowback.
First, let's examine the important parts of the blowback marker. (Pictures to be added soon)
Valve Assembly
The valve assembly contains 4 important working parts. The valve itself is where air enters
the working part of the marker. Sealing the valve when the marker is at rest is the
cup seal, which is attached to the valve pin, and pushed flush by a spring. The
valve pin rides in the valve and directs air to different parts of the marker when the
cup seal is pushed back. The spring keeps tension on the cup seal and pin, allowing the
marker to reseal when it is done firing.
The Striker and Bolt Assembly
On the other side of the valve, is the striker (Also called the hammer). The main spring
is between the striker and the velocity adjuster. The striker is attached to the bolt by a
rod that sticks between the two tubes. The bolt is attached to a cocking rod (rear cocking)
or has a cocking lever on the side.
Trigger Assembly
The trigger frame itself contains a trigger, a sear, and several springs. The trigger
has a paw on it, that releases the sear, which starts the marker firing if it's cocked.
It all comes together
Amazingly, it all comes together. First, the marker is cocked using the cocking rod or
lever. The striker has a tab that catches on the sear, and compressed the main
spring. Once the trigger is pulled, the paw pushes on the sear, pushing the sear down
and releasing the striker. The striker strikes the valve pin, pushing the cup seal back
and allowing air to enter the marker. Meanwhile, it also pushed the bolt forward, pushing
the paintball into the barrel. The valve and valve pin direct the air flow in two different
directions. Some of the air goes up into the upper tube though the bolt, propelling the
paintball through the barrel. The rest of the air pushes against the striker, pushing
it back into the cocked position, where the sear catches it. Meanwhile, the spring in
the valve assembly pushes the cup seal back into place, cutting off the air flow through
the marker.
Common Problems
Marker makes a hissing sound or leaks air down the barrel
This usually means that the cup seal has worn down. First check the cup seal to make
sure that there is no debris blocking it from closing, and that the spring is still
pushing the cup seal back into place. You can replace the cup seal itself, or replace
the cup seal and valve pin.
Marker does not recock and sputters
There are two possible problems here:
- It could be that the sear or sear catch on the striker has warn down. If the
marker sputters untill you take the air off, check the sear for wear. Also,
check the catch on the striker to make sure that has not worn down.
- It could be that the striker o-ring is bad. If your marker eventually either
cocks or stops uncocked, you should replace the striker o-ring. This looks
like a tank o-ring but is slightly bigger, so make sure you use the correct
one, or else it will not fix the problem.
Does not fire when trigger is pulled
Either the trigger paw has worn down, or the sear has worn down where the trigger paw trips it.
Check each for wear.