I haven't heard of a grizzly color in pigeons, what is that? Actually, I have to admit I haven't heard of a lot of pigeon color varieties at all.
Many lovely varieties exist, different colors of plumage & even frizzled plumage which looks like a pigeon got a perm at a beauty salon
Their eye colors can vary, as well. The colors they can see is more wide ranged than our vision.
Videos
I think some folks rush training. When I trained my Homers, I let them fly around freely daily for about 3 weeks, noticing when they do start to flock up & fly as a team...that part is essential, if they're still flying haphazardly, like a bunch of "wrong ways" do not attempt training just yet. Once they flock up together & are in the air flying large circles for a few hours, & taking off exploring together & flying back together, they're building stamina & learning their area, sticking together, then begin taining & train every other day, or 3x a week, weather permitting. I never fly in rain, sleet, snow or 100 degree heat wave or very low cloud or fog weather or storms forecasted when they'd be flying back home. The weather app will become your best friend. A cloudy day is often a hawk day, at least here, hawks will be at my loft hanging out, so very cloudy days are dangerous, for my group anyway. The very 1st release is just to get accustomed to being in a release basket, crate them up & sit in the shade about 15 minutes & only it's an acre away from the loft, within sight of loft, on my own property, I do a few releases like that, so then they learn...oh this is kinda fun, like a game or challenge. It actually becomes easier to catch & crate them as soon as they see the basket, they know, hey we are going for a ride & flight. They even get to know my phrases, "want to go for a ride?" Or "want to go out?" Or "Come on in" & the "come on in" is important for when I want to call them in, they can be flying in the air & if I say come on in, they will land on the landing board & go right into the loft to safety. This has been valuable with approaching storms or when I just need them in. I get them used to these routines, repeating them. I release 2 acres away in all directions.
To me, my most valuable tidbit is this...If They beat me home, I change direction or distance. If I beat them home, I release from same point again. I only increased distance or change direction, when They Beat Me Home. They are learning, Not only where they are but also determining who among them will lead. In time, you'll notice, who are the few that lead, kinda cool how they work that out themselves. Then when they beat me home, I increase distance slowly, 1/2 mile, 1 mile, 2 miles, 4 miles, 6 miles, 10 miles, 15 miles, 20 miles, 30 miles, always switching direction or distance When they beat me back home, north, south west of my loft, (east if I could, but beyond 2 miles east is the bay, which I have flown them over but not anymore, too time consuming for me by boat lol). My training is every Other day, weather permitting, their day off they just fly around the yard or if they choose to go roaming, they may. In 23 years, I only lost 1 group of 6 birds one time. My training may be slower than some folks, but I don't like losing my birds. There are hawks, overhead high power wires to avoid, bodies of water to navigate over (bays & rivers & the ocean nearby) so I take my time letting them learn & do not rush them. Most times they stick together, but if they come home separately, sometimes days or weeks apart, it may be due to hawk attacks, or joining up with someone else's flock, I really don't know. A few came home with broken legs which I splinted & they healed wonderfully, an injured wing, sliced open crop, etc. They are amazing & do their best to make it home. I used to race, there are various distance races, my birds did good. The last race was released in Atlanta, GA, a 600 mile race, & a hurricane down in the Gulf changed direction & headed towards GA. The jackass released our birds in a hurricane. Many lost entire flocks. I only entered 4 birds, but got 3 back home. I never raced again, I was so ticked. Anyway, you don't have to race them, I don't anymore & I just love having them share my life.
Some interesting reading...
https://intoyard.com/pigeon-eye/
https://learn.genetics.utah.edu/content/pigeons/color
. You just cant free fly them,,,,,,,, possibly forever. Homers will return to their original loft. 
