1. 28" barrel will not slow down a 7mm-08, unless you have the load reduced to the point its half of what it should be. On that particular load you will gain 20 to 30 fps per inch of barrel gained.

2. In total reverse a 28" barrel is the one to watch for gaining too much pressure and velocity for the action to handle it. I had a browning 1885 with a 28" barrel that couldn't handle my loads that my ruger no.1 would shoot just fine in the 26" barrel.

3. Same goes for revolvers vs. contenters or levers gun with pistol cartridges. They hold 1/4 the powder that your 7mm-08 does and they gain an amazing amout of fps in longer barreled guns without hitting a dead space up to 28-30 barrels. You can take a pistol round and stick it in a lever gun and make it act like a 30-30 as far as ft lbs go.

4. Longer barrels hold the advantage to gaining fps without having a maximum charge of powder behind it. Barrel length will make the equivalent of shooting premium loads without the wear on the rifle and the price of purchasing premium cartridges if your not a hand loader.

Something might have been wrong with your last 2-4 inches of barrel but that's unlikely. A 26" barrel is just about perfect length for gaining that extra fps without the damaging pressure behind it. That is the reason for most of the manufactor's to start putting them back on their hunting rifles. For awhile only a few had them on their rifles. Short barrels are very nice to carry in the field but they lose when it comes to long range fps and ft lbs.