....although Armed Forces Pension Schemes are usually considered to be non-contributory, the salaries of all Service people are abated by an amount agreed by the Armed Forces Review Body to take into account the value of the pension? This is currently 4%, a not insignificant amount and is a contribution about which you, the contributor, have no say."
Your final salary pension is then based on the net, ie:96%, value of your pay, so we would be better off getting the pay rise & then making a contribution. Unlikely to happen though.....