They gain weights at their own speed like people do. I have 2 - 3 mths old that are 550 grs. 2 - that are probably the same age as yours that are 195 grs and 187 grs.
I would say thats about average. As Snickers said, each chin is different....some mom's produce more/fattier milk and the kits fatten up faster. Your kits are growing just fine
Agreed, growing is growing with chinchillas. There really is no size chart for chins younger than adults. Heck, even with humans it took years to set up standardized size charts no purpose to in chinchillas, at this age if they're gaining they're good. Your chin that is average at 5 weeks may be a whopper at 10mos. OR your chin that's huge at 5weeks may be a runt at 10mos. The same reason not too many dog breeders put much stock in teacup size charts Growing = good. To answer your question, based on MY data, those weights are about average for that age. They say, as a rule of thumb, 100g/mos is a positive thing at this age