I feel like they are two totally different animals, one really won't make you stronger on the other. Dumbbells give a better fuller rounder appearance for my chest. barbells give me a wider flatter look to my chest. that's just my own experience. overall i like dumbbells better if i had to choose one, but they are both necessary i believe for overall muscle development.

Found dumbells much better for shoulders and general hypertrophy, especially for upper chest (incline) now concentrate heavy lifts on bar to deads and squats only.

I was to a point that flat presses were wrecking my shoulders. Moved to dumbells and all the support muscles were activated. Took the pressure off my delts/joints and added thickness and balance. Its easy enough to switch it up every 6 to 8 weeks back and forth. I believe in changing workouts every 2 months. Volume vs time between sets vs supers and drops etc. Fatigue builds us up

I don't speak on this but if ya know ya know but I've been in the heavy iron game for a few ticks and yeah when it comes to increasing bench press, dumbbell flat bench won't do the job and most powerlifters know that, not debatable. Now some guys might benefit from other dumbbell exercises that help their bench no doubt, but flat db press ..nahh. There are certain muscles to target like Seeohshow mentioned that will help increase your bench. I'm keeping it simple because there's alot more to it trust me. I don't wanna get all scientific and sheeet! But he gave you good advice honestly. Just watch out for injuries and lift smart. I told NWA that I just had a slight rotator cuff issue but had that issue many years ago so no big issue really but ya never know what happens on that flat bench messing around with a certain amount of weight or really any amount from what I've seen from folks.

You have to think of it like this mate - One exercise uses a long fixed bar which you are able to get leg and back drive into and the only direction you have to balance it is forwards and backwards so it is very easy to direct force into it. With Dumbbells you are having to balance them in 4 directions as well as up and down and often have to expend energy getting them into position too, so they recruit a lot more stabilizers. You should try solely using a barbell and then going back to dumbbells, that will REALLY humble you as you will be weak as hell with them lol

Quite a few well known powerlifters rate Incline Dumbbell presses as being a great exercise for increasing bench mainly because of the shoulder involvement and probably as the incline involves the triceps quite a bit too. I've helped a hand full of guys increase their flat barbell bench on here and the best way to do it is do a Barbell only bench session of say 3 heavy sets close to failure, then leave it 3 to 4 days in between and then repeat again, or however it takes for you to no longer be sore. Keep it going like that striving to increase weight and reps each time in one area or both. Drop any other chest work such as dumbbells, dips, cables etc.

Also leave shoulder training alone for the time you are doing this in terms of any shoulder pressing movements - if you are benching heavy and frequently then your shoulders will already be sore enough from benching and any further soreness will make progression difficult and will hinder your bar power/speed which you are trying to increase when getting stronger. Do things like lateral raises to the side and front with dumbbells as this will keep the shoulder girdle strong overall and the front delts will get adequate work from benching. If you follow this outline you will greatly improve what you can lift over 2 to 3 months, but if you start throwing in other exercises and don't stick to the plan, and chase the 'pump' rather than increasing plates on the bar then you will stall or find it much more difficult.

In terms of pec development from barbell benching, this comes down to how far apart your hands are from each other and your ideal hand spacing. I have 2 hand positions/spacings I use for pressing and the difference between the 2 is literally an inch at either end - so overall the distance is altered by 2 inches. If I use the wider of the 2 distances then I get great pec activation, a full on pump across the whole region and I am pretty strong in it too - but it does put extra strain on my shoulders which is the downside. If I then bring them in just 1 inch at either end then I am stronger as my hand is stacked directly over my elbow joint and my forearm is perpendicular to the floor - but I get virtually ZERO pump or chest muscle activation from it. Its crazy how such little changes can make a massive difference to your physique. So maybe that is something for you to play around with in terms of hand spacing.

I did dumbbell presses only for a long time and my barbell bench got stronger. But when I do barbell presses only my strength with dumbbell presses doesn't go up. Dumbbells for me build more strength but not if you can't get a hold of heavy dumbbells. Most gyms don't go past 120lbs.

I think it depends on the persons structure. The bar path puts you in a rigid position and it’s just up and down from there, basically. So if that position/posture doesn’t hit your chest perfectly and give good pump and soreness then dumbbells may be better for you. But if you can hit the chest perfectly with barbell benching than barbell is 100% better than dumbbells.

For me I stay away from the bar because my stronger side takes over too much and one pec starts getting way out of proportion and so does the opposite front delt, but with dumbbells each pec is forced to lift equal weight. Plus the deep stretch you can get is killer

Barbell everything just gets a guy big. I love those plates singing as I'm throwing that bar and I believe working with that heavy ass bar gives a different look. Dumbells are cool but... barbell>dumbell

As far as dumbbell bench pressing...man I haven't done that in many years, I'll do dumbbell overhead shoulder presses but I'm all about that barbell for bench pressing.
Again can't give much help on dumbbells but I suggest reps of 8 to 12-15 ....then drop immediately to the floor and hit push ups for a burn out. Maybe a pause in mid position. You'll feel it.

Another good post by Chuck Duck.
So I've had a talk with a few guys in my gym about this in the past. No dumbbell strength doesn't equate to barbell pressing strength at all. One of my buddies repped 120 pound dumbbells with relative ease but yet he couldn't come close to a 315 pound barbell bench press. Surprised the hell out of me. It was strange man. I'm a barbell bench guy but dumbbell presses I find did give me a better stretch and sometimes better pump but that just depends. And no dumbbells DO NOT increase your barbell bench press, barbells do that. Like I said I'm more of a barbell guy but I do incorporate dumbbells in my workouts from time to time.

I like heavier for barbell 4-8 rep range. And lighter for DB work 8-16 rep range. Will start my push day with heavy compound movement (flat/incline) and after 3-4 heavy working sets where I can’t get 4+ reps in the set without dropping weight then I transition over to DB pressing for about 3-5 more working sets in that higher rep range. Then my chest is done. Then tricep work will be things like weighted dips, close grip bench, tricep push downs etc.

But my bench is weak as fuck compared to my legs. Bench ~330 but squat ~500