I have heard that Remington only makes one run of 7BR brass each year, and unless you are really on the ball, it will be gone before you have a chance to buy any. The xp-100 I converted to 7tc was originally in 7BR, so I had it rebarreled to 7tc. I campaigned an xp in IHMSA silhouette for about 15 years and did well with it. But 7br brass is tough to find and there are tons of .223 brass, so that decision was a no brainer. Case capacity is about the same and I never have to worry about finding brass.