Breastplates were usufull in central-eastern Europe in XVII century yet. In 1604 King of Sweden, Charles IX, invaded Poland to conquer eastern Baltic area (today Latvia).
King of Poland sended next year only 4000 "winged hussars" against swedish army (11 000 soldiers).
Both armies met at village Kircholm 28. september 1605. The battle was the massacre of swedish troops. About 6000 Swedes were killed in the battle. On the Polish side - about 20... The secret was simple: heavy armour of Poles (max. 8 mm !) vs. low quality of swedish muskets.
In the castle in Liw (central Poland) there is one of the largest collection of armament, in that number numerous breastplates of that period. Allmost all of them have marks made by musket balls, but only two of them are perforated!
Battle at Kircholm was great shock for swedish army and the next king of Sweden, Gustavus Adolphus, reformeted his army completely.
One of his steps was to buy for his infatry much more better muskets in Holland. Swedes invaded Poland next time in 1626 and we lost the first confrontation - the battle at Gniew. Our winged hussars were decimated by the fire of new, heavy muskets of swedish infantry.