At least if he was using RL26 he wouldn't be running way over pressure like he is with the H4350. With the info given he is running a bit over 70,000 psi with the H4350 load. I had to chuckle because he is talking about people with the 6.5 CM using RL26 shooting 2900 to 3000 fps and saying they are using dangerous loads. When in fact that is what he is doing with the H4350 out of his 260 Remington with the 27" barrel.
If he switched to the RL26 he could get a bit over 3000 fps and still be within 260 Rem pressures. The problem is he thinks because he is not seeing pressure signs he is fine but most pressure signs we look for does not rear it's ugly head until we get a little over the 70,000 psi mark, and with the action set up well with good brass it may take more pressure. Most modern rifle can handle that pressure without a major problem, it is just there is no buffer for things like fouled barrels, extreme hot or cold a bullet getting jammed a bit to deep causing initial pressure to spike. A catastrophic failure is just waiting to happen.