I have some H4198 left over from reloading 45-70, and I'm looking to make 55gr plinking loads.
I'd like to hear from anyone who has used H4198 in 223.

I've used it and the IMR version, mostly with 50 grain varmint bullets.

Gave up a little speed but had damn good accuracy. 22" bolt rifle was getting 3200 fps with 50 grain Nosler.

I shoot the same load in my ARs, OAL is change to mag constraints but a good shooting load, noticeably better than 55 grain fmj but that's probably due to the bullet more than the powder in that comparison.

either 4198 will work, running from 15 grains to 22.5 grains in the 223, with 55 gr SP or FMJs...

The lower charges are for a bolt action....20 or more should work with an AR...

Thanks for the input.
On a whim, I tried 21.8gr of H4198, CCI450, LC brass, 55gr Hornady 55gr fmjbt, 2.2" col. But my chronograph had a stroke so no velocity from the 16" 1/8 barrel (unless ERR1 is a secret encoding of the velocity numbers). Seemed a fairly mild load that gassed enough to 3 o'clock my brass.

I know H4198 is less than ideal, but it is what I've got on hand.