Because of the significantly smaller internal volume of the 45Super case, due to the heavier web and thicker lower sidewall area while holding the same external dimensions, the same weight of powder charge as used to a standard 45 can have quite different initial pressure and velocity results. So do not assume the result will not be greater for a 45super load listed that is nearly the identical powder charge as a 45+P formula. Similarly, AOL of loaded rounds should be held to tighter tolerances. Older powders really needed barrels longer than 5" to take advantaage of the higher developed pressure. Some newer powder burn curves allow faster powders without spiking the pressure excessively. Also, since powder formulas and performance change over time, use of old loading data can have unexpected results. Always work up the loads while checking for excess pressure signs. A change of primers from any listed reload data can have several percent total pressure results. Internet formulas by 'I use this' home loaders should not be considered reliable. Recoil springs should be considered both for the final compressed weight and the initial in battery compression weight. A couple nanoseconds longer in battery can allow time for the bore pressure to drop considerably and reduce the slide velocity, lowering the total compressed recoil spring weight required. Assuming you are using 45super to wring out every extra bit of velocity, the extended aftermarket barrels can still have beneficial results. 6.1 inch barrels are available for the XD model. Solid, ported or threaded. Over about 5.7" may need to be ordered manufacturer direct.
Because of the copyright on the 45Super name, other similar high velocity 45 cartridges and load data may be found as 45Express.
The most often quoted of supposedly reliable 45Super references are:
Real Guns
Real Guns
Also an interesting article in American Handgunner archives: "Heavy Bullets and the Springfield XD45". Not 45Super but of interest related to pistol strength.
And a Google search of the XDTalk forum should turn up some 45Super discussion from at least as far back as 2006.
Edit: Because of the recoil spring limitation with my XD45Service, I am limited to playing in the 45Super power range, but for an XD45Tactical, I would definately consider the jump to 460Rowland for serious hunting. 460Rowland kits have used both Bar-sto and Storm Lake barrels (among other possibilities I haven't read about). 6" barrels are needed here to get the benefits of the round.
ABOUT:
.45 ACP 21,000 cup
.45 ACP +P 23,000 cup
.45 Super 28,500 cup
.460 Rowland 40,000 cup
Done, someone else's turn.