Yes - time past, the nipples were called tubes. By the mid 1800's, they had a restrictive opening, either top, or bottom, to limit pressure coming up the 'tube' and setting the hammer to 1/2 cock position.
Through the 1870's and 80's, ere were a number of cheap production cap-locks which did exactly that, but oft times, it was due to the locks having a coil spring as well as not enough height to the cock, at 1/2 bent position.(1/2 cock).

What a lot of people do not realize, that is when shooting bullets, conicals, minnies, etc, - elongated bullets, - the breech pressure is greatly increased, and the restrictive little hole gets burned out prematurely.
Back in the mid to late 70's when I was shooting bullets from a Bauska 38" twist .50, I replaced the nipple once a week and cut off and re-crowned the muzzle every 200 shots. That was due to using a fiberglass rod, which wore the muzzle from 1" groups to 2" groups in 200 shots. I had apertures at that time and the gun was an easy MOA rifle. I was also shooting modern 3-postion and prone competition at the time, using both optics and apertures.