pre-primed parts are simply not available,
its a nice idea but you'd never be able to attach the hoses without introducing some air
to be honest you can bleed the system with just a length of rubber hose that fits over the bleed nipples tightly
and you then run the other end into a clear vessel ( jam jar)
I favour having a clear hose from the nipple to a jar 1/2 full of old fluid and with the nipple closed your assistant pushes the pedal up and down a few times then holds it down then you crack open the nipple and close it again whilst fluid is still flowing.Repeat this a few times on all calipers and start with the caliper furthest away from the master cylinder.
If you still have an issue then it could be a flexible brake line is ballooning under pressure, this can't always be seen from the outside so to test this use a hose clamp on each line in turn to close off then lines one at time . Push the pedal in between and see if you can feel any difference as each line is closed off.
now garages may use a vacuum pump to draw the fluid through which does make it easier but you can achieve a good result with an assistant to help
do you still need help?
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