some answers for you guys:
yakkingallover:
1. for self-defense rounds, I suggest you try the Gold Dot 135-gr. 38+P Short Barrel load first. If that's too strong until you get your hand conditioned, try the FC 38 (NOT +P) 110-gr. PD load.
2. For practice, at first, or for friends to try this gun, I would recommend the typical 38 Special 148-gr. DEWC round--the "softball load."
Unless you are a very experienced shooter with a well-conditioned hand, do
not shoot 357 gr. high-velocity loads.
MarvinKnox:
from #533--
re tritium sight. I would determine what sight picture puts your preferred carry ammo under the dot. For example, if you've elected to carry the GDSB 135-gr. 38+P load, shoot the round the way you normally do--then, adjust your sight picture if you need to. FWIW, I use the front sight for a flash-sight-picture only.
for the CT laser grip: I tweak the laser settings to that my carry ammo is dot-on at 15 yards, regardless of how I shoot with the front sight. There is no need for "continuity"--
whichever sight you use has to maximize your defensive response.
As for the best way to use the sights:
Use either one--front or laser--to develop proficiency at a quad five. Do NOT worry about "aiming," get the 5-shot group to be in a five-inch diameter. Once you can get the group in five inches in five seconds, then 'concentrate harder' (again, using either sight) to get the group smaller.
If you find ingrained marksmanship habits are forcing you to take longer to develop a sight picture, get some personal instruction to help you break these habits. With a 340, you're developing personal defense handgun skills. Any shot further than ten to fifteen yards is probably irrelevant. In fact, state law may almost demand that "fight or flight" decision if the conflict distance is greater than fifteen to twenty-five yards.
from 534--I found the Speer 38+P 135-gr. was nominally "spot on" at 10-15 yards. S&W 38 Special front sights have typically been regulated to shoot to POA with standard 158-gr. load (appr. 755 fps) at 25 yards; I think that is true of the 2" j-frames as well. Regardless of the factory defaults, Speer tweaks the powder recipe to provide that--and it can vary from ammo lot to lot, I have found, but not really more than an inch.
External ballistics are not going to play any sort of meaningful differences at ranges under 25 yards--see the "details" pages
here for more information about, for example, the GDSB 38+P 135-gr and the GDSB 357 Magnum 135-gr. rounds.
Generally speaking, higher-velocity rounds will print lower, and heavier-weight rounds will print higher--but strictly speaking, velocity POI is a relative relationship for two rounds with the same bullet weight, and any correlation between POI for different bullet weights is determined by real-world tests by individuals.
so, from 535--If your hand conditioning is sufficient to keep the same control with the GDSB 357 135-gr. round as the 38+P 135-gr. round, the 357 shot should be lower. In the real world, I have found that the "muscle memory" I have impacts that actual experience. If I'm "used to" shooting the 38+P round, the 357 round prints higher if it's the next few shots, even though it runs about 100 fps faster.
So yes, I would forget the ballistic differences for the time being. And, I would not worry about more esoteric variations on ammo selection and longer-distance defensive scenarios.
Jim H.
Before I zoned, I agreed with everything he said. 
