I went over this for a long time in my mind. I came to the decision that 'KISS'keep it simple stupid. All guns are different, but what is 100-150fps in the field, Nada! With new powders and bullets, your 6.5 will equal a 22" barrel 270 of 50 years ago. Please 270 fans this is not ment to start anything. I have used Lapua brass up to 6 times in three different 6.5s with no problems to date. I am not flaming anyone who has one, but it just dosen't make sense to me. If you want more than A 6.5, get a .264.capt david

ditto to that. I have 3 ackleys in the house and all 3 outperform the parent cartridge and approach the belted magnum of the same bore dia. I have gotten 3200fps out of a 6.5-06AI out of a 26" tube and a 140gr a-max with no pressure signs. However,..that is because I subscribe to the theory of the ackley shoulder which leans on a better ignition and burn inside the case due to the sharp shoulder. That being said,..far slower powders can be used in the AI's and that boosts velocity with a longer pressure curve due to slower burn rate. I have done it and chrono'd it for myself. Flat primers come a long ways after ejector marks,..and I don't even have any of those.

The 6.5x55ai that I am in possession of (someone else's) will go pretty damn fast with the likes of N165, RL22, etc. definitely NOT the old school 6.5x55 performance of 2600-2700fps.

Your mileage may vary,..but I will continue chambering in the AI calibers. Even if no improvement comes with it,..the brass lasts much longer. That alone makes the conversion worth it,..especially if you are paying to have a barrel chambered in the first place,..in that case there is no additional cost. I also have great luck working the load ladder while fireforming,.so NO barrel life is sacrificed.

Just my usually contrary 2 cents worth...



The 6.5x55 is a very underrated cartridge, because the published loads have to take into account the original Swedish military Mauser. In mine, 3085 fps is easily attainable with 120 grain bullets, within safe pressure specs for a modern firearm, using a 24" barrel.



The 6.5x55 is already a little overbore to begin with. That means you have to add a lot of case capacity to get any signficant increase in speed. It also means that as you go up in capacity, your rifle will get more finicky, and your barrel life will significantly decrease.



As mentioned, the Ackley design does offer significant advantages other than speed.



If you do have the need for speed, the 6.5-06 mentioned earlier is a very fine round.