My tri's have always been good but not as good as my bis...
but recently ive found that not locking out on tri movements better target the belly of he muscle making it more full
anybody else found this
Mes, i agree with you that sometimes this is better-by avoiding lockout you're increasing TUT (time under tension), which is one of the intensity techniques considered effective in stressing the muscle to beyond what it's used to and forcing adaptation thru growth.
As you probably know, everyone should try different variations on each exercse, because each case is different and also because even for the same exercise different variations will be effective. For example on pushdowns, another good approach is to lockout while doing partials but then only do the bottom 1/2 or 2/3s of the ROM, with elbows wide-very effective yet different from what you're doing, which is yet another way that obviously works.
Besides TUT, one of the big reasons avoiding lockout works is that partials are a big fave of mine as one of the keys-try avoiding lockout AND then at other times try avoiding the other end of the ROM, which is sometimes another area that isn't as effective on the muscle. You can avoid the other end entirely OR cheat thru the first few inches of the other end. For example cheat curls or lying extensions. Another example of this is preacher curls-avoiding the bottom and the top of the ROM is more effective both because it stresses the bis better. In all of these cases, removing parts of the ROM and making it a partial thru the sweet spot of the remaining ROM does several things: it makes the movement more effective, it increases TUT AND it reduces it reduces injury potential by taking away the most stressful parts of the movement in terms of connective tissues and joints.
Hacks are another example, i never bother with the bottom of the ROM both because the sweet spot's the upper part and because it's hard on the knees. Same thing on squats, i've always found box squats AKA partial squats more effective. In both cases we're talking about locking out but avoiding the bottom of the ROM. That works for me, for others it might be the opposite, removing the lockout and/or the bottom, to increase TUT and focus on the sweet spot, which is what partials do better.