The error with the adaptor is that it is designed for markers with a 45 degree angled feed already to the side and to bring it vertical for the hopper.
The BT already has all of that built in
A trick for sighting with markers is to keep both eyes open and look 'through' the feedneck, hopper etc.
Its easier with a non stocked marker - put the cylinder in your shoulder, rotate the marker in front of your face and look through the body & barrel etc. You are then pointing where you are looking.
The effect works if each eye is on either side and you focus up ahead.
A but harder with a stocked marker
The BT already has all of that built in
A trick for sighting with markers is to keep both eyes open and look 'through' the feedneck, hopper etc.
Its easier with a non stocked marker - put the cylinder in your shoulder, rotate the marker in front of your face and look through the body & barrel etc. You are then pointing where you are looking.
The effect works if each eye is on either side and you focus up ahead.
A but harder with a stocked marker