I've been looking for a good hollow point .40 personal defense round to use in my M&P and during my google search most come up with 180 gr rounds.
In .40 S&W, any decent JHP from a reputable manufacturer at 155-180 grains is going to be pretty effective; I'm not saying that others wouldn't be (some lightweight, very fast all-copper-bullet loads are excellent), but this is a safe bullet weight range for JHPs in this caliber.
Whats your opinion? Lighter faster bullet or the slower heavier bullets?
In this caliber, standard loads have pretty similar momentum, regardless of bullet weight, so the most important deciding factors are reliability and shootability, which depend on the individual handgun and shooter. The only way to know for sure is to try them out for yourself.
Personally, anything seems to work for me and my primary defensive handgun, although I slightly prefer 180-grain JHPs because they're more pleasant to shoot, due to having less blast, flash, and snap. It also doesn't hurt that 180-grain loads are some of the most heavily-used in law enforcement, and that they generally have a good reputation for effectiveness in that application.
abq, are those 180's loaded light? Generally, a heavier bullet, if loaded to spec, will kick harder than a lighter one.
Heavier bullets tend to "kick harder" in terms of total momentum transfer (recoil impulse), that is true, but some people may be more sensitive to peak force (often perceived as "snap," I suspect, and could be interpreted as "kicking harder"), for example, which in many cases is significantly higher with lighter, faster bullets, all else being equal. And since the total momentum tends to be similar, by and large, for 155-180-grain loads in .40 S&W specifically, it's not much of a factor here anyway.
kyarcher, heavier bullets will of course penetrate better
All else being equal (which in practice is rarely the case), heavier, slower bullets appear to penetrate more in soft, wet media (e.g. the human body), while lighter, faster bullets may have an advantage in hard, dry media (e.g. walls and car doors). There are a lot of other factors involved, however.
but all in all, it depends MOST on the accuracy as to which would be better for you. Whichever one shoots the best from your firearm and YOU are the most comfortable shooting (practicing) with will be the one you want to shoot. Penetration doesn't make a tinkers damn if you miss!
Yep!