Horse heavy on my hands...

So I have been riding my horse Hope in the pasture I keep her in. I have been riding in a halter and leadrope and she responds to it just fine. I notice sometimes she feels heavy on my hands when I am turning her. Any suggestions....

Also the last time I rode in the pasture I got a little canter out of Hope I was soooo excited. This is a horse that hasnt cantered with a rider since she was raced as a 2 and 3 year old. I didn't have to ask much just moved my leg back and clucked to her and she picked it up....Good Hope

I would ask her to flex at a standstill, I.e, to bring her head around and touch your boot with her nose. Do this on both sides once or twice, it encourages softness. I generally do it every time I ride, at least once.
It's amazing the difference I can feel if I don't ride my Foxtrotter for a week or two, then take him around the pasture. Generally at first he'll be tough to steer and it feels like your trying to ride a brick with legs. After I ask him to flex, he's much more responsive and lighter, and the 'riders flow' is established, even if he's being an absolute turd that day it's a much better ride.

But be sure to ask for the flex. Don't drag their head around and try to make them hold it there, you'll have one peeved horse :) I normally like to start flex exercises on the ground with some treats. Same principle as under saddle, ask the horse to bring their head around and reward the effort, even if they only get it halfway.
Try to think of it as you trying to learn how to do the splits. You gotta start out at the beginning, and work your way up to your goal. If you try to rush to the end...ouch!

I use the vocal cue 'Flex' with a tap on the side I want them to bend. Then I move up to saying 'Flex' with pressure with a lead rope or long rein. After that, we move up to undersaddle flex cues. Nothing beats a supple horse!

I'm not sure your problem is totally related, but look at this thread Riding a horse that leans on hands...

I've worked with ex-racers and they respond very well to halter/lead rope cues but not so much to bit cues because they are trained to be extremely heavy on the bit. When a jock pulls back on the bit in a race, it means the horse needs to go faster. Ever notice how tight the reins are the entire race? Unless they've had extensive training to lighten this up, they will continue to be heavy on your hands, especially if you use a snaffle. Put a hackamore on her (replace the chin strap with a leather strap if you can... they appreciate it much more!) and see how she does. They'll recognize the pressure on the bridge of their nose from the hack noseband because of them being taught the same thing in a halter.