+2 for Roasted Barley. I use around 4 oz. per 5 gal.
Red X is an interesting option, but you’ll have to use a lot more than RB to get enough color contribution. At that level it will bring a bunch of malt flavor, kinda like Munich Malt.
I use a small amount of roasted barley and 70-80* L cara / crystal malt in Irish Red. This gives a rich red color but adds caramel flavor. When I brew an American Red I skip the dark crystal and roasted barley and use 45*-60* L crystal and add a little Carafa 1 dehusked chocolate malt to add red color. The lighter colored chocolate malts at 2-3 oz will also add red color.
There is nothing that looks as vibrantly red as a 100% Red X beer at 1.050 or so OG, once it drops completely clear. But the flavor of that beer just isn’t for me. Red X tastes in the ballpark of a very dark Munich spiked with a bit too much Aromatic/Melanoiden malt. It’s just too strongly rich for me to drink in any great amount. Sure looks great in pictures, though.
Roast barley and CaraRed will help push a beer in that direction, but at best you will get a reddish amber. One other way to get brilliant ruby red color in your beer is cherry juice if adding fruit is an option.
At the bottom of this BYO article there is a recipe for a Vienna called Red Ball Express. I brewed it years ago and I believe I recall it being a nice red color.
I agree I’m not 100% sure I love the flavor. At YH a red lager was our flagship beer and I tried to use Red X for ease but it was not something I personally enjoyed. Sinamar is what was and probably is still used. Before that a cold steep of Carafa Special II was made and added directly to BK.
For roast malts intended for color, they get turned into a find powder in a coffee grinder. The powder goes in at Vorlauf to minimize flavor extraction.