.223 Remington
Powder: H4895 Charge Weight: 21.6gr
bullet: Hornady 77 gr

Barrel 10.5"
Muzzle pressure 16225 PSI

Barrel 16"
Muzzle pressure 10429 PSI
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300 BO (sammi)
Powder: AA#9 Charge Weight: 18gr
bullet: Hornady 110 gr v-max

Barrel 10.5"
Muzzle pressure 7786 PSI

Barrel 16"
Muzzle pressure 4526 PSI
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Data is from quickload use at your own risk If you have a specific load you want me to look up add it in this thread
General conclusions, Faster burning powder generates less pressure at the muzzle. Powders with similar burn rate and charge weigh will generate similar muzzle pressure.
 

Your numbers are suspect
Dr Dater's numbers using actual instrumentation.
M855
@10.5in bbl = 11.5kpsi
@16in bbl ~ 7.4kpsi

They may not be accurate

I’m using data from quick load

Disregard any further I guess

Thanks for the correction

I'd like to see more muzzle pressure numbers of various cartridges and barrel lengths.

You can do the math and be extremely close.
There are threads that contain such info.

I would put them up but apparently quickload does not calculate them properly.

Take your loads chamber pressure at it' given volume (cc of load).
Calculate volume from base of seated bullet to muzzle.
Do some division.

I add 25% and it's usually right on. The 25% is a poor way to factor continuing powder burn, but it's easier than actually doing the math and I haven't been significantly off, yet.