I am trimming 7 mag rounds. The specs say to trim to 2.490 and I over trimmed to the 2.489-2.475 range. Would it still be ok or did I just ruin some brass?

Why is there a range? They should all be the same.

In any case, as long as you have .284" of bullet in the case mouth they'll work. Shoot them two or three times before you trim them again. They will grow longer with every firing. When you do go to trim them measure 10 cases, and write down the numbers. Set the trimmer to the shortest length you measured and trim them all to that length.

thanks for the help fireman. This was the first time I ever used a case trimmer and was experimenting with the new trimmer and obviously messed up. So I need to make them all the same....gotcha.

Handloads outshoot factory ammo. Because they're hand made and they are more consistent. So keep everything consistent including case length. When experimenting loads the rifle likes or doesn't. Only change one variable at a time. Charge weight, seat depth, primer brand, bullet weight and type, ect.

RedRaider99- while they should all be the same you may not get those exact same results. I have found that if you are within .010 either way you should be "OK." However there should never be any longer because you can trim them again. In a round the size you are resizing you may have a bit more "range" but .010" is my max.

My .308/7.62 has a target of 2.005" but I will use brass that is 1.995" or longer. Again you re-trim long brass so having it long isn't permissable on my reloading bench.

Trim a piece of brass to "trim to length" Paint it red and use it as a standard tool to set your trimmer and calipers next time.

**If your case length varies it will affect your crimp tension. But with rifle you don't really need crimps.