Mid size grip
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Unfortunately bigger grips won't really help, you're flipping because of something you are doing in your swing. Good chance you don't have the weight far enough forward at impact. I would recommend taking a look at Key #1 and #2 videos.
Yep, I have to agree with this post. I tried to cure the same problem you are having with mid sized grips. Didn't work. I found out I didn't like the grips either and they were top of the line GP muticompound. When it came time to re grip again I went back to the Callaway stock grips standard size.
By the way, one of the pro shop guys at the course where I play the most saw one of my flip shots that went short and to the right. He told me I was all arms and that I wasn't clearing my hips out of the way because I didn't turn them enough on my takeaway. I listened and on the next hole turned harder with my hips and upper half until I was looking at the ball over my left shoulder, no more flip.