shoulder seams, Old vs Modern

[Kiem]

Hello Everyone,

I am trying to find out some more about shoulder seam placements on waistcoats and coats, overcoats.

The older drafts I see usually have the shoulder seam placed further on the back, compared to the "modern" shoulder seams with lies more on top mof the natural shoulder line.
I refer to these as the old and modern shoulder seam, not sure if this is correct, but for now this is what I call them

Is this correct? the modern seam placement seems to be 1/4 inch forward at neck point and 3/4 forward at shoulder point, compared to the older style.

Is there a pro/con to either of these?

I have some trouble fitting a low shoulder on a waistcoat with this old style seam placement. I made a few waistcoats with the seam placed more forward and dropping the slope shoulder did not give me any problems.

For example, I drop the shoulder point and deepen the armhole like I did with other waistcoat low shoulder alterations.
But with this older shoulder seam placement it messes up the back neck completely. The back neck is really loose and high after the drop shoulder alteration.
Before the alteration the fit was ok.

It literally ruins the fit, where as the waistcoats I made with a modern shoulder seam placement, I have no problem at all with the exact same alteration.

I am starting to think this might be due to the shoulder seam position.

Can anyone shed some light on the matter? Maybe there is some clear reasons why this seam position changed that I am not aware of.
No pictures for now unfortunately.

[peterle]

Placing the seam more to the back brings the seam out of sight. It also makes the back shoulder line more bias and thus it´s easier to shrink it in to avoid a shoulder dart. But the front needs more ironwork.
Your problem: when doing a drop shoulder alteration you have to take out a wedge along the true shoulder line evenly from back and front. When you take out the wedge on a backward shoulder, the wedge is taken mostly from the back only. This messes up the fit.
Your solution: Mark the true shoulder line in your "old shoulder" pattern and do the dropped shoulder alteration with the true shoulder line. Treat the small part as part of the back. When finished, rejoin the leftover of the small part to the front.
I encourage you to do both alterations and compare the results.

Please keep in mind that old patterns often differ from modern patterns also in other aspects than the shoulder seam placement. (for example more crooked shoulder, pigeon chest, tighter neckhole, ecc.) It´s up to you to compare.

[Kiem]

Perfect explanation, thank you!

I found out I made a stupid mistake on the back shoulder. I had let out the back part shoulder point to compensate for my forward shoulders... that made the back slope too square and pushed the cloth off the neck. Once I had altered the shoulder point back to the original pattern line it solved the problem I had created myself 

Nonetheles, super helpfull comment!

[Kiem]

Is there a way to measure/determine where the natural shoulder line should be on a pattern that does not have the shoulder seam on the natural shoulder line?