Just curious if anyone out there has any experience with 260rem
I'm thinking about rebarrelling mine with a 29" tube does anyone know if I'll be able to get up around the 3000fps with the 140 grain projectiles
You will need a 32" plus barrel to get there and not trash brass. With my 32" I can get 2900 to 2950 that is not hard on brass. The use of slower powders help.
I am a 6.5 fan, but my experience with the smaller cases is with the 6.5x55, rather than the .260 Rem. Without laying on the throttle too hard, my accuracy loads with 140 VLD's tend to come in between 2750 and 2850 from a 26" barrel, depending on the powder I am using. I would expect the .260 to yield similar performance.
Assuming that your chamber is properly throated for the 140 VLD's, a 29" barrel should be enough to get you to 3000, or very close to it, with RL-17. From what I can tell, you will have to go above book max pressure to get there, though not by a lot. Your OAL will also likely be longer than mag length if you build on a short action.
Going with a larger capacity case would help you reach 3000 more easily. It all depends on what you are comfortable with and your intended purpose for the rifle.
Here is an article that contains information about the .260 Rem, and similar cartridges, that you may find useful: