Can you do a narrow shoulder adjustment in place of a full bust adjustment?

As someone who always has to do a full bust adjustment (FBA), I've long wondered whether it would be possible to replace this adjustment with the simpler narrow shoulder adjustment. If choosing a size based on your full bust results in a too-big shoulder, wouldn't doing a narrow shoulder adjustment on that size fix the problem? I decided to try it out.

Can you do a narrow shoulder adjustment instead of an FBA?

My standard procedure in adjusting top patterns for my shape is to cut a bodice according to my high bust measurement (usually about two sizes smaller than my full bust measurement indicates), then do an FBA and a full bicep adjustment to accommodate my full bust and arms. But I figured the narrow shoulder adjustment was an easier one to make, and might negate the need for a full bicep adjustment, which I usually need.

I used the Liesl + Co. Metro T-Shirt pattern for this top and decided to hack it into a turtleneck. I'll be sharing a tutorial on that in a few weeks, but in the meantime, here's a post about the fitting.

My high bust is 36" and my full bust is 40." My full bust measurement (and my waist and hips) corresponds to the size large in this pattern, and my high bust with the medium. I have a 13.5" bicep. The size large sleeve finishes at 13.25". I wanted 1" of bicep ease, so I needed a 1.25" full bicep adjustment. So, while using the size large did not negate the need to do a full bicep adjustment, but it was a smaller adjustment that required less fiddling with the sleeve cap. So far, so good.

I looked at the difference between the medium and the large shoulder widths, and decided to narrow my shoulders 1/4".

I also did a 5/8" high round back adjustment and a 1/2" forward shoulder adjustment. My tops always tend to slip back on my shoulders. For years I did forward shoulder adjustments, but they never really did the trick. I've been playing with the high round back adjustment lately, and while it works better for me than a forward shoulder alone, it still wasn't a perfect fit. Finally it occurred to me that I might need both adjustments. This is the first garment on which I've tried both in tandem and it worked!

I only had a yard of this rayon/lycra knit, so I had to cut the sleeves 4" shorter than the pattern calls for. I really wanted a longer sleeve, so I ended up cutting cuffs out of the fabric remnants.

Substituting the narrow shoulder adjustment for the FBA resulted in a top that I like and will be happy to wear. But it's definitely not as effective a fix as the FBA and larger full bicep adjustment. It's not just my shoulders that are narrower than my bust measurement indicates; it's my entire upper chest. So while the shoulder seam is in the right place, there is a bit of excess fabric in the armscye. With this drapey knit fabric, it's not a big deal, and I might use this technique again in the future for knit patterns. But when sewing woven patterns, I think I will need to stick with the FBA on the smaller size. 

As always, thanks for reading, and see you next time!