I have used a hot water weaker citric acid solution on suppressed brass for about 30-45 minutes with some success, but it seems to ‘etch’ the brass a bit. Be interesting to see how you get it done in 3.5 minutes without hitting the brass too hard.
I , like many of us use a universal de-capper to de-prime cases . After I initially clean MY brass one time ,I do the following after shooting .
I'll run the brass in the universal de-capper pop spent primers ,then place all My cases in a Anchor Hocking bread loaf dish ,set into a bath of de-ionized water . I then pour My cleaning solution directly into the glassware dish with cases in it . I've already preset the heating cycle of the bath water . I ensure the water level is near full ,without either contaminating the other . So solution and cases glass dish is full ,as is the surround water . Turn on unit ( now ) with preset timer 3:30 minutes . End of cycle drain clean bath water ,into a 2.5 gal. plastic jug , I then remove glass dish drain while straining solution . Rinse cases thoroughly put them into My Dillon media separation hopper and lock it ,flip the motor on and around and around the cases flop ,not allowing water to set and drying at same time . As I've yet to build the force dryer ,I'm using a 16" #3 speed fan on #2 setting and it blows directly onto cases . Takes about 20-30 minutes for complete drying .
IF I'm gonna run cases and restore ductility via My modified Annealeez ,I'll cut drying short by 10-15 minutes .
Sometimes IF I want Pretty cases ,I'll either rerun the ultrasonic or simply pin tumble ,so as to remove most if not all the witness marks .
I introduce ductility ( what many refer to as annealing ) after every #3 firing on bottle neck cases .
I'm happy to report I've as of Yesterday gotten #29 firings on 1942-68 LC .30 Cal. cases and I load near top end . Haven't lost a single case nor tore any rims and if anyone has Garands they know that's remarkable in itself . As we all know Gas Guns aren't the most forgiving extractors .
Those original once fired cases had set too the weather for 45-50 + years before I got hold of them and were UGLY ,as in triple bagger UGLY !.
I must have measured perhaps #250 New Lapua cases in various calibers and found something interesting ,from the case mouth south the witness mark is 0.591 down the shoulder towards the body . Once I started duplicating that heat signature , MY cases began sealing as well as lasting longer . Restoring the neck & shoulder ductility most certainly lessons carbon neck shoulder ring as well as gives pretty consistent velocity . So knowing a little more than the average person ,due in large part to Norma . I believe the secret is NOW revealed as to Lapua's Case success .
Fyi: I found by changing frequency of the ultrasonic ,I was able to clean even the rebated rim groove substantially better ,thus giving desired quick cleaning results .