The load seems to be a load for Remington rifles only, but lot# of powder, barrel to barrel differences, brass differences, should always make a person back off on a load listed and work up. If you check 5 different loading manuals, you see 5 different max loads. For this reason, any printed load should be worked up to, even max loads in reloading manuals.
One thing for sure, 7-9 twists jack up pressures, and chances are you would have to beat the bolt open with any 9T barrel you ever shot the load in. This is why I listed the warnings. Remington 223, 12T owners would pick up on the load in a hurry, and with the warnings I gave, they should work up to the load also.
Biggen0 8's load with N135 will equal the benchmark velocity load I listed(or excede it), but he did not elaborate much on the velocity or accuracy. I did not mention the N135 load due to how scarce the N135 is, and the fact that N135 has pressure spikes when temps get over 80*.
In my 9T, the accuracy load is at 24.5g Benchmark with a cci 400 and 55g bullet, absolute max load in this rifle is 25.5g of benchmark.
If a guy has been reloading for 50 years, everyday can be a surprise in how a change in primer, very little change in seating depth, change in lot# of powder can alter the accuracy and pressure of a load. Now if you throw in letting your ammo get hot sitting in the sun, you are really in for a shock when you go to open the bolt.
Novices in reloading are in for many, many surprises as they learn. The attention to the load that I gave for Remington 12T 223's is a good subject to educate the novice in what to do and even more important, what not to do. A guy should always work up to any load listed, sooner you learn this, better off you are.
No doubt the safest thing to do is not get involved in Reloading questions and issues unless the conversations are between very experienced competitive shooters or gunsmiths. Way too many things can be misunderstood or taken for granted.