You might also want to take into account where you place the thumb wheel. If it is swung fully out ie away from the release body, you have got a great deal more leverage than if it is swung fully in. Therefore the pressure that needs to be applied to compress a given spring will be much less. To max out the pressure on my Target 4 i fitted the strongest springs, but it was still to soft with the thumb wheel swung out, so I swung it in and it was then fine.