Did you know that 98.7% of all posts quoting percentages are made up? 
As far as my methodology -- I used a recoil calculator that uses SAAMI's formula for calculating recoil. I compared factory SD and target rounds from different manufacturers. I compared some initial results to known results to make sure I wasn't producing anything anomalous. I did CHOOSE 180 grain for .40 and 230 grain for .45, and I did so specifically because that's what those calibers were built around. Then I ran comparisons of comparable factory loads in those bullet weights, and when I say "comparable", I mean from the same product line from the same manufacturer. I also ran comparisons from the data in reloading manuals using those two weight bullets with bullets of the same type at velocities as close as possible to the velocities that the caliber was built for. The "made up" percentages you see in that post of mine you quoted are averages of my results, and not only are they averages, but they are averages rounded to the nearest five percent. --Oh my God! He admits it!-- I didn't go too specific on results or methodology in the initial post because 1) it would have been little help to the OP, and 2) the reality is that a claim that .40 was 32.3% stronger in recoil than the .45 in a 2.5 pound 1911 invites more criticism than a nice rounded 30%, and 3) there's always some guy who is going to come along after the fact and try to disprove an entire claim with one flaw in methodology, even though the flaw doesn't directly impact the result or change the result in significant way. "You didn't take into account lot-to-lot inconsistency in powders!" I find that being general often gives the jerks less to work with. Of course, being general sometimes leaves you looking like you made things up or are guessing wildly, giving people who happen along with their preconceived notions an easy path to dismiss you. And for the record, that proverbial "guy" who comes along and dismisses for a minor flaw in methodology -- that's not supposed to refer to you. You dismissed on an assumption of dishonesty.
Were you aware that the majority of posts in gun forums from people regarding commonly held truths about things like felt recoil, bore-axis, glass-rod-like 1911 triggers, Glock grip angles, etc. are just people misrepresenting other people's misrepresentations of other people's misrepresentations of other people's experiences? You can tell because there is no way millions of shooters can experience something independently and come to describe those experiences with the exact same words. It's quite human, of course, very much has to do with how we learn, and there's no way around it, but it does lead to myths.
Anyway, I've shot 40's in polymer and all steel, and 45acp's in both as well.
So you haven't tested .40 against .45 side by side in the same platform. Maybe you should.
Think about it. The 40 is traveline quite a bit faster than the 45 and not much less in weight.
I don't have to "think about it". I've done the math. And I've done the practical application, which supports the math.
And for the record, I'm not sure how fast YOU think these bullets travel, but the .45 was designed around a 230 grain bullet travelling at 850 feet per second while the .40 was designed for the FBI requirement of a 180 grain bullet at 900-1000 feet per second, for which I CHOSE 950 feet per second for the calculations based on published reloading data. And, for the record, common factory loads do reflect those velocities. So your "quite a bit faster" .40 is going 12% faster than the .45, while 230 grains is 28% more than 180. Not much less in weight? It's almost like you started with a pre-conceived notion that .40 recoils harder than .45 then made something up that to justify the claim.
