Your recruiter lied. Makes me wonder what else he lied about.
The US military doesn't really have a retirement 'system' in the traditional sense. You are not making payments into a plan, there is no vestiture, you don't get to take your money with you if you leave before you are retirement eligible because there is no money invested in a retirement plan.
When you accumulate 20 years of active federal military service you are eligible to retire. You can hop from one uniform service to another (say, do 5 years in the Air Force, then join the Army) and your time accumulates, but time accumulated as a civilian employee of the government does not count towards military retirement. Two completely different retirement systems. At 20 years the DoD simply 'gives' you 50% of your base pay for the rest of your life. If you leave at 10, 15 or even 19.9 years you get nothing. When you reach 18 years of active federal service you get 'locked-in'; it damned near takes a felony conviction or an act of Congress to get you tossed our before you make the magic 20 mark. It CAN happen; every once in a while you read about some moron who got kicked out on a drug, drunk driving or wife beating charge at 19 and a half years of service.
"At the end of the day the Glock is what it is - an extremely well designed and executed, accurate and utterly reliable combat pistol that is not a 1911. And for many folks that is the unforgivable sin."