The middle picture with the tape is too dark to count lines so I tried to visualize the tape as being on the gun in the top pic. I came up with 26 but I'll go with you 2-piper on 28 lines per inch. These guys need a thread guage to accurately measure the checkering. It is far from the 40 lines per inch someone stated in a previous post. 40 lines per inch would mean that there is only .025 of an inch between lines.

Practice safe eating. Always use a condiment.