H-1000 is a bit slow-burning for the 270, especially in an gas-operated automatic. I use H-4831 in my M70 270, but IMR-4350 should work fine. It's just a hair faster than 4831. These powders, along with others having similar burning rates, are needed to reliably cycle your gun.
I have afew autos, mostly military, like M1 Garand. The only sporting auto I have is a Remington M81 300Sav, but it is recoil-operated. I do have a couple of friends that have 7400's in 30/06. They both have told me stories about them failing to extract or not fully going into battery. But these guys are not into any sort of gun maintenace whatsoever. They just pry the shell out with a knife and they think it's fixed. I would recommend keeping the chamber clean and dry, stick to factory-speed loads and you should be ok.
Hello Riflemen: I do not know how the slower powders like H1000 and IMR7828 work in the 270 auto's but I do know that the H4350 and the IMR4831 powders work great. These IMR and H powders often mimic each other in their numbers but they are not interchangeable. Try a faster powder! BestLever