4227 is just a powder with a certain burn speed like all the rest.
Its relative speed is about 250, the fastest shotgun powders are
about 7-800, 4831 rifle powder is about 100, the slowest bmg
powders about 70. All powder has about same energy per grain.
We can use so much more of the 4227 as it is slower in a much
bigger bore than a pistol.And 775gr slug is light for an 8ga.If you used
1500gr then you'd cut powder back about 2/3 as much.We lab tested
90gr 4227 in 12ga with 600gr slug and average of peak pressures
was under 15,000 psi. That is like some magnum factory slug loads,
of same slug weight,only we get 3-400 fps more. Not because of any
higher peak pressure, but due to slower burn rate powder the average
pressure the full length of the barrel is higher, thus more velocity.
And it takes more of slower powder to keep that barrel pressure
average higher. But we use this as a gimmic to get more velocity
without fear of to high peak pressure.I that load was the fastest
shotgun powder it would spike to over 100,000 psi.
Here is picture of RIP's two 12GA FH NEFs.
Both are the 12ga Ultra Slug Guns.
One has Vias brake, other expansion chamber.
He calls it his golf ball launcher. Ed