I've got two savage M12 BVSS's, both started out life as 22-250's. One I shot the barrel out of so I rebarreled it with a 22-250 criterion 9 twist. The other one I pulled out of the box and put a criterion 8 twist 6BR barrel on. Both of them go on prairie dog hunting trips with me but the 22-250 gets used far more often, it's my go to PD rifle and I use 55 gr. nosler ballistic tips in it. The 6BR gets used when the shots are long, I use 105 Amax's in it and it's got an 8-32 nightforce on it. It's probably my most accurate rifle. It's essentially a single shot, it won't feed the 6BR case and the ejection is iffy, most of the time I have to pull the cases out by hand. Both the 22-250 and 6BR are braked to make spotting hits easier.
55 gr. bullets out of a 22-250 aren't anything to sneeze at, they'll hang in the wind pretty good and give good acrobatics on prairie dogs. For day in day out PD shooting it's more fun than the 6BR. The 6BR pretty much only comes out when one is hanging out there in the stratosphere, my record with it is 880 yds. The 22-250 gets the nod for anything inside of 500 or so yards. One of my hunting partners has a very accurate 8 twist 243 for the long shots but does the majority of his dogging with a 223. The 6mm's are just a bit much for all around use, the 22's fit the bill better in my opinion.
I debated the AI chamber but in the end decided to stick with the standard one. The standard chamber is extremely capable already and the brass trimming is blown out of proportion. I have 500 cases and the barrel probably has around 2500 rounds through it. I've trimmed the brass once and it's getting close to time for a new barrel, this one is starting to copper pretty badly. It's going on another PD hunt this spring and I'll see how it does then make the decision to rebarrel or not. The next one will probably be an 8 twist criterion instead of the 9 twist, but in all honesty the 9 twist had done everything I wanted.
