T-shirt pattern quest pt. 6 : How to correct the fit of the armhole of a fitted t-shirt

I created some drawings to further explain the armhole problem on my t-shirt pattern. Nearly all drafting instructions that I've seen for t-shirts are pretty much the same. First you enlarge the armhole and drop the shoulder. Then the front and back bodice are traced off with identical bodice shaping and armhole shaping. The only difference might be the neck. If you lay the pattern pieces on top of each other, you will get something like this.

This kind of pattern works ok for a boxy, loose fitting t-shirt. If you want a more fitted t-shirt, then it simply won't work. In my case, the symmetrical armholes caused the front of the shirt to be pulled toward the back. The closer the fit, the less symmetry in general. When you look at the human body, you can see there is no symmetry between the front and back so patterns should reflect this. (Most people are not truly symmetrical left to right either). Children generally are more symmetrical than adults and the patterns for them reflect this. But, even there, the more fitted the style, the less symmetry though the differences are smaller. Anyway, the patterns above resulted in a fit that looked like below. The red arrows help emphasize the shape and length differences of the front and back armholes.

To correct this problem, I needed to lengthen the back armhole. I compared the armhole of my blouse pattern, which was not symmetrical, to the t-shirt armhole to determine how much longer it should be. Slash and spread and the pattern should look like something below.

 With a result that looks much improved.

The next thing on my list is to make adjustments for front versus back body width.