Too many unknown variables to give you meaningful information. It will depend on the specific dimensions of the chamber reamer used to cut you chamber, the bullet you choose to use, the barrel you select, and the list the goes on. I have model 70 260. It has CDI bottom metal and uses AI mags. I currently use a Barnes LRX bullet. Accuracy is great and I have no issues with magazine length. The gun will also shoot Berger VLD's quite well, however, they are too long for my AI mags. I can use Alpha mags and I don't have a problem. However, the alpha mags don't run as smoothly as my AI mags. I am told that you can remove the plastic strip that is in the front of the AI mags and you will gain a touch more length. I have not tried this. If you know already know what bullet you want to use, you can talk to your gunsmith about using a reamer that will allow you contact the lands and grooves without exceeding your overall length limitations of the standard AI mags. I shoot with a number of competitive shooter that use 260's they don't seem to have a problem with accuracy.