Flex vs. Stub nib

Opinions?
I do my best writing with a flex nib (Ahab). I have tried different stub nibs - Lamy 1.1, 1.9 - and I can't get any marked difference from a regular M nib. I don't know if it's the way I hold my pens, the angle, or what. I read Civil War era documents and think "I can write like that." I can create a form of Spencerian, but it's more easily replicated with my flex nib pens. It seems I should be able to do it with the stub without the actual flexing part, but for some reason, I just can't get the benefits of a stub nib.
If you think of the straight/flat part of a stub nib, my natural writing position is not perpendicular to the lines on a page. I hold it more at a 45. Maybe I am defeating the advantages of a stub.
It's kind of a bummer.

I am by no means the master of the stub, but it sounds like you are holding the stub correctly. You are getting roughly the same result that I get with stubs; I can see some variation compared to my regular nibs but it's not incredibly pronounced, just a nice subtle variation. I have mainly smaller stubs with my widest being .8 mm or so.

As far as recreating Spencerian, I can't really help you there. I'm using a bastardized form of Spencerian for my main script but long ago gave up on flourishes to make it look pretty. I'm just not an artist in even the loosest sense of the word.
If you haven't already, head over to Fountain Pen Network and poke around in the Handwriting section - there's some (what I would consider) genuine masters of Spencerian script who might be able to steer you better.

Good luck

Thanks.
Mine is by no means straight Spencerian. I don't do all the flourishes, etc. I try to do something closer to what you would find on everyday documents.

Stub and italic nibs 'work' by staying in one alignment to the page, going "up and down" to make a fat line and "side to side" to make a thing one. It could be that you are turning you hand (and thus your pen and nib) as you write, so you never get the variation of line caused by the nib going in different lines of travel.

If you're not getting a marked diff between a medium, a 1.1, & a 1.9, then there's definitely something wrong.

Thanks for the replies.
I'm getting a difference between the various nibs. The difference in variation on the different strokes of the individual nibs isn't as pronounced as I thought it would be.

stubs take a different technique, the tip needs to remain at a 45 degree angle or so in relation to the vertical lines on the paper to make goo line variation, its a subtle difference but its there.

Stubs are designed and intended to give less variation than crisp italics or cursive italics but to also be more forgiving than the latter two.

It is a matter of the actual edges of each type of nib. Crisp italics will have abrupt and sharp corners. If held properly they will provide the greatest line variation of the three but also if not held correctly they will catch on the paper.

Cursive italics round the corners slightly to prevent catching on the paper if not held perfectly flat on the paper but that also reduces the line variation slightly.

Stubs round the corners even more and so are the most forgiving of the three but will also show the least variation in line.

Flexible nibs behave entirely differently and produce an entirely different line. They are designed to provide different widths regardless of line direction based on the desire of the user at that moment.