This won’t be exact science….
I often heat AR to around 100F* while creating around 200ml of a saturated solution of sulfamic acid in water at the same temperature. Once both are at temperature I gently and carefully add the sulfamic to the AR. Often the first few drops are added being less than 1/2 a plastic spoon and often around 1/4 plastic spoon as a test to check the reaction. I only use this method when I know the remaining nitric will be minimal. The watered down version will delay the reaction but will not reduce how aggressive it can be. It also seems to affect how the lead may react in AR. If I know larger amounts of lead are involved I prefer to use the sulfamic directly. Not being science educated it seems logical to me that two liquids would combine better to form an expected reaction. At least in the situation of AR and sulfamic acid.
I often heat AR to around 100F* while creating around 200ml of a saturated solution of sulfamic acid in water at the same temperature. Once both are at temperature I gently and carefully add the sulfamic to the AR. Often the first few drops are added being less than 1/2 a plastic spoon and often around 1/4 plastic spoon as a test to check the reaction. I only use this method when I know the remaining nitric will be minimal. The watered down version will delay the reaction but will not reduce how aggressive it can be. It also seems to affect how the lead may react in AR. If I know larger amounts of lead are involved I prefer to use the sulfamic directly. Not being science educated it seems logical to me that two liquids would combine better to form an expected reaction. At least in the situation of AR and sulfamic acid.