I am a console player, otherwise I would try to figure this out myself using the cmd console/ debug mode/ GECK/ etc.

I am curious if the JSP/ hand-loaded rounds eliminate the need for AP rounds. Mostly interested in the .308 caliber rounds, but info on large caliber rifle (not pistol) rounds would also be appreciated and informative to myself and others. The hand-load rounds have a fairly decent dam multiplier, and I was wondering if this increased damage is enough to offest the counter-DT effects of the AP rounds. Again, since I am not playing on PC, I cannot personally investigate game mechanics such as this, and I do not know how the AP round mechanics work as compared to the hand-load rounds. Any PC players who have the time and know-how to investigate this? Or, any links to info related/ regarding ammo mechanics in FO:NV?

The 1.5x damage from the JSP 308 cal will increase the damage from what is it 50? per shot to 75 per shot in the sniper rifle. If I understand this whole DT thing that means it negates 25 points of damage threshold extra from the normal bullet while the AP round only takes out 15 or so. I'm on the xbox so I've checked all of this info in-game and JSP round seem to do way more damage than AP rounds, even on the same creature.

^pretty much my general feeling/ experience as well, playing from xbox360. Would still be interested in some hard data from PC users.

In my experience the JSP works better against all foes, armored or not. It's all I use now. I believe Arcalamus pretty much broke it down correctly. DT is directly subtracted from the damage you do. For instance, using This Machine my base damage is 65. If I'm shooting a Deathclaw with a 30 DT (ignoring all other factors including Crits) I'm at 35 with the .308, 47-48 with .308 AP, 23-24 with .308 JHP and 67.5 with the .308 JSP. JSP wins hands down. On low armor targets the difference between JHP and JSP is negligible. Take a DT of 5: JHP = 99 while JSP = 93. I'd just rather keep myself loaded with the one ammo for simplicity sake. Anyone not wearing armor is going to be low level and is down when getting hit with 90+ damage either way.