When I purchased my FA the only thing I was really set on was that it be ordered new from the factory. From my 454 I knew the 6" barrel length was a good compromise between the portability of the 4" without some of the recoil sting. I figured if I had a choice, I would choose the 500 because it was unique. Though I know you want a answer to your question and not a diatribe, at the same time I'd also say the " optimum barrel length" is the one that you are comfortable shooting well. If you are shooting low velocity loads, of which there are many, IMO, you'll never really notice the difference in recoil. It just never becomes a factor. However, there is a point in which you start surpassing the limits of other cartridges, and the pain associated with a a few pounds of steel driving into your flesh is a good indicator of the 500's wild side. Even with some of the moderate pressure powders, it was more than I could handle. So, I would drop the charges such that the velocity was in the 1200fps range based on ballistic charts. This is comparable to what I shoot in the 454 minus about 100 grains, and obviously smaller sectional density of bullet.
I know most of GBO members are hunters so perhaps you need a certain level of performance. Id think the build
quality of the gun and the characterstics of the handgun cartridge translate to a nominal difference in accuracy when
your eye is unaided, regardless of barrel length. I used to have a 9" FA and I struggled with balancing it, esp. when
scoped. That's when I knew 6" was right for me. Regarding that 9" 353, the combination of longer barrel and
cartridge type never ended up causing any sort of pain. I would load slower propellants I could only dream of loading in the 454 or 500. I can't recall the exact load data but I was loading either 180 or 200gr bullets with the
Vihtavuori powder that is similar to Hodgdon 110. Even this was a pussycat load. I do not believe a equivalent load in
the mammoth 500 WE would be tamed by a few inches of barrel. Yeah, the degree to which the muzzle tilts, may lessen but still I think the shooter is the limiting factor. There is just too much energy produced.
If you are reaching case capacity or are having an issue with bullets pulling in your AE, the WE will fit the bill. And the octagon barrel is a nice option and again, in my opinion, looks better in a longer barrel. But, pretty sure the ounces increase over the round barrel will not have any affect on perceived recoil. Sure does look cool. You may want to consider picking up one of the previous FACA publications. It has a full review of the Editor's 50AE conversion to
the WE. Pretty sure it had a custom (octagon) barrel length--like 8" or somethin' and really impressive trigger and hammer polishing. Exactly what you want. I have the issue but I unfortunately I don't have a scanner to copy for you.
I am sure others more experienced will chime in. Good luck to you.
