Hello all,
I just set up my account here. Learned helpful things here in the past. Looking forward to contributing.

I would like to get some info and opinions from y'all on 9mm home defense/carry ammo. I live in a small apt. with 1 other person. I'm concerned about overpenetration (into other apts.) since the longest ranges I would be dealing with in a defensive situation would involve a wall to a hallway, adjacent apt., or the exterior of the building no more than 10 feet from me. (Like I said, small apt.) I do however obviously need something powerful enough to do damage to a threat.  

I have an xdm 3.8

Thanks in advance

Speer Gold Dot, Remington Golden Saber, Hornady XTP or other HP. If you have to shoot someone worry about hitting your target no putting rounds through a wall.

From what I've dug up while choosing ammo, the XTP penetrates more than the other premium SD hollowpoints (14"+ vs about 12") and expands less.  

If you're concerned about shooting through an interior wall and into the next apartment, I'm not aware of a round that will be stopped by drywall but penetrate enough to be adequate for self defense.  You'll just have to try to score solid hits if you have to defend yourself.

This may be helpful, it can be found tacked to the top of the AR15 Ammo forum:
Best SD Ammo

Any ammo that penetrates deep enough to kill a person is going to penetrate through several layers of drywall, I would get some good HD ammo, and invest in some training so you can hit what you are shooting at, Bad Guys make great back stops with good quality HD ammo. In the Ammunition section under pistols you will fina FAQ section that will point you in the right direction as far as HD ammo goes, typically the best are 147gr and 124gr variants as 115gr except for a one or two doesn't penetrate enough to meet the FBI standards.

Here:http://www.ar15.com/ammo/project/Self_Defense_Ammo_FAQ/index.htm#9mm

Welcome aboard

Welcome to Arfcom.

I live in an apartment and have Speer Gold Dot 147gr in my G19 and two spare G17 mags. Excellent ammo and all I carry regardless of caliber. I practice/shoot drills mostly with Speer Lawman though I'll just plink with most any brass or aluminum ammo.

Welcome

Educational reading from one of our esteemed members.

http://www.theboxotruth.com/the-box-o-truth-12-insulated-walls/

Many articles and tests regarding ammo penetration through walls and stuff.

Unless you are going to use  something like Glazer safety slugs or some kind of frangable round, stick to Winchester Ranger, Speer Gold Dots, or Remington Golden Sabers. The new Hornady rounds are good as well.  There is no such thing as short range defensive ammunition.

Speer gold dot bought from "sg ammo" online is the best deal around for HP IMHO

This is crucial to understand and SO MANY new gun owners just don't understand it.   Handgun/shotgun/carbine ammo that is good for SD/HD will all penetrate about the same through drywall.   The best way to prepare for minimizing over penetration is to train to hit what you shoot at.   Sound simple but under stress on a two way range it can be deceptively difficult.    Good luck brother!