Bad Coil Gun Nailing
Here are the problems with Coil Guns in just 1 shingle.
Coil Guns come with a set guide for a reason = so your shooting nails square, flush & at the proper spacing on the shingle & siding every time.
Many installers remove the guide or just completely ignore it.
Running a nail gun without it , or at an angle , or sideways is a botched roof job every time.
The average roof is about 30 squares & the average shingle count per sq. is 60 = do you want 1800 shingles like the 1 above installed on your roof
See pics below