I know it's hard to give suggestions based on a written description but I need some ideas on what to try. My horse is a head horse, has been pretty much his whole life. I feel like I've finally got him making nice even circles with the right amount of bend while keeping his shoulder from dropping and swinging his hip out... (on his own now instead of me keeping him like that) that's on "dry" work... now when we got to lope the barrels, I haven't asked for speed yet because I want to make sure we are correct more than anything, it's almost like hes breaking at the pole too much? Maybe behind the bit too much? If that makes sense... then the shoulder will drop, especially to the left (head horse) so right now I'm riding him in the bit I use for roping... it's really all I have... I own a bunch of ported bits and chain bits but all geared towards roping. It's a ported bit with longer shanks .. dont know what it's called but it works really well for when we rope because he tends to get a little strong, this one keeps him in check. So what I'm thinking I'm looking for is something with lift that's also light because he tends to be very soft (unless we are roping) probably a a happy medium, I want to keep him soft, light mouthed as possible, but respectful.  I'm kinda wanting to stay away from chain bits because I feel like he has no respect for them, at least when we were roping.. feel like we've ran our course with chain bits.. I have about 5 different ones and I dont like him in any of them. 

use your leg to cue him instead of bridle. the turn on barrels is same move head horse makes in corner. lift ribs, drive with hip.

Is he trying to evade the bit by breaking at the poll too much and being behind the bit? Usually, that's what most are doing. In those cases, going to something "lighter" can be helpful.

I re-trained one a couple summers ago for my aunt. Horse's history was a bit unknown but he was supposed to have had a bunch of reining training. I personally think the guy didn't know what he was doing b/c horse totally evaded the bit (nose to chest) and had no idea how to follow his nose, since he could lope with his nose in one direction and body moving in the other. Basically no body control whatsoever. Best thing I did for him what little to NO arena work, got him on the trails. And I actually put him in a basic O-ring snaffle (no curb at all) and he was perfectly soft enough for that, and I just worked on staying off those reins and letting him re-learn to be a horse again. Works on teaching him to respond to my legs  and teaching him how to use his body correctly.

He really surprised me and "came out of it" pretty quickly.

If you are currently using a ported bit, it might just be too much for him, with what you are trying to accompish on your dry work. Do you have anything right now maybe like a Jr. Cowhorse maybe with the 3-piece mouth? Or something similar? Or for the heck of it, in the arena doing drywork, stick a plain snaffle (no leverage at all) and see how he feels. Sometimes it doesn't work (didn't with one I"ve work on the last two summers) but you never know unless you try.

You can still use what you need to use when roping to have enough control, but then use a different bit for when you are working on other things.

I ended up finding this chain bit in my tackroom and tried it out on him, plus I focused on using more leg than anything, I had forgotten how well he responds to leg cues, my bad... hes extremely responsive to leg pressure, I was focusing on too much of my hands to get what I wanted. Anyway, he was much more free in this bit and I was really pleased with him the other day.  Huge difference in his turns, a lot less stiff. Thank you for the responses! We have a lot more work to do but I feel much better now about it, at least on the right track