actionflies:
You need to be more specific with your load data for your 9mm load before I can determine whats wrong with it.
I didn't know Precision Delta made jacketed bullets. (I know Bobby Tranum, owner of company).
He buys the Jacketed bullets in bulk from outside vendors. The last I saw were Hornady. (its been about 4yrs since I saw him, or his ammo at the NRA Police Nationals at Jackson, MS)
First, you have to match the propellant to the specific bullet.
Precision used to produce the most accurate factory ammo for 9mm. A LOT of NRA PPC records were set by it by the Miss. Highway Patrol shooters. Not so, since changing bullet and powder vendors.
For the 115gr Bullet, I find that it's necessary to seat the bullet a bit deeper than you are (1.156"). I seat the Hornady 115's (and very similar Montana Gold) as well as Rainier HP to 1.10" oal. With the Remington 115JHP, I use 1.125", which is what P-D used before they swithched to Hornady bullets about 10yrs ago. This seats the bullet deep enough in the case for proper alignment and minimize run-out.(you can check for this by rolling the loaded round on a smooth flat surface such as a counter top. The tip of the bullet shouldn't wobble).
I've found that Win #231 is excellent in the 115gr @ 5.0gr (what P-D used before switching to a "cleaner" burning powder) However, I prefer Winchester SuperField @ 5.2gr.
For the 124gr bullet, you can seat a bit further out. For the Remington,Speer, and Rainier, I again use 1.125". Again, I use WSF @4.8gr
For the 147gr bullets, I seat to 1.135" oal. (most all HP's). And, I use 4.5gr of WSF (note that this is~+P loading). This too, is what PD used to use before going to IMI630.
Anderson Cart. (of Greenville,SC) used this in their 147JHP along with a Hornady 147gr XTP before they closed up shop. Many competitors favored this over the P-D offering as they seated the bullet out a bit further (P-D still used the 1.105" oal that they used with the 115gr load, but a lighter 4.2gr charge- (at least in the two lot#'s I pulled.).
I hope this helps steer you in the right direction.
FWIW; the XD's DON'T have polygonal rifling. It's conventional in the two I own.
FWIW; my XD9 subcompact will shoot ~2.5" at 25yds.,also my XD45, with "select" loads. (but the S&W PPC-9's I use in competiton will shoot ~1.0" or under. My 5" PPC-9 shot a .770" six shot group last Wed. with the Nosler 115JHP @ 1.080"oal, over 5.2gr of WSF in a OFB Precision-Delta headstamped case [starline] and a Winchester small pistol primer.)
With a cast 120gr TC, I use Hodgdon's LongShot at 1.080" oal
(how much, I won't say! I cast the bullets, too.). From my 6"PPC-9, suffice to say it's a ragged hole at 25yds, for as many shots as you want to put through that 1"x1" hole. (after 12rds, the hole don't get no bigger than that).
Thats the load that my XD9 likes. In the 45XD it's a 200gr SWC @ 1.255" oal over 3.8gr of Hod. Clays.
I doubt that your XD9 has a .356" or larger bore. Mine's right at .355".