Would/should that be safe with a 40 grain 223?
You couldn't put enough Lever behind a 40gr bullet in a .223 case to cause any problems.
Look at something similar of similar burn rate like CFE-223.
You are not going to get 32 grains of lever in a .223 case....
I think you are probably right, but I wouldn't make that assumption about Lever just based on Quickload. It might work well under a 40gr 223, but you may run out of powder room a little below max.
I'd have to check this evening, but since 29.0gr of Lever fit in my 20 Tac cases easily, I think a normal 223 case should fit at least 31gr, don't know about 32.
If you want to use a different powder for 40gr 223, forget CFE223, Ramshot XTerminator is where it's at. When I was shooting a lot of the 40gr V-Max and BT, XTerminator gave the best accuracy and velocity in that old Rem 788. As a point of fact, best accuracy with all of the bullets I used in that range happened close to max loads.
Also - use the Western Powders load guide for that stuff.
I followed up on this today. As dropped from my RCBS powder dispenser, my sized LC brass holds 31-31.5gr of Lever, full to the top of the case neck. With a little tapping to settle the powder, 31gr is about halfway up the neck, and 32gr fits without overflowing. However, it's still too slow/bulky for best results with a 40gr bullet.
I tested it with the 40gr and 50gr V-max today in my 16" 223 Wylde, working up to 31.0gr of Lever under both. The 50gr Vmax averaged 3445 fps, which was similar to the 3415 fps that my standard load does with 28.6gr of X-Terminator. (Yes, that X-T load is high for 223 specs, but about right in line for 5.56 data if you interpolate a little bit with what Western Powders publishes. It's also a load I worked up that gives good case life and accuracy in cooler temps like right now, but should be backed off a bit for hot summers.)
The 40gr Vmax with 31.0gr of Lever did 3410 fps, indicating that Lever is just too bulky for best results with that bullet weight. X-Terminator and a couple other powders can do significantly better with the 40gr.
Just based on what I saw today, I think in my rifle's 223 Wylde chamber at least, Lever is probably better suited to 55gr and heavier bullets.
Also for comparison - this same rifle with the 75gr BTHP / 25.5gr Lever load mentioned by The Kid does 2720 fps, at least in these cooler temps (~45° F). That load can be pushed over 2800 fps in this rifle without sacrificing case life, as long as the gas is turned down. It's not at all friendly to suppressor use though, with a lot more gas in the face compared to the Benchmark or 8208 loads described above.