Suggestions for .223 using H4198

[Historian]

I recently purchased some Sierra 65g Gamekings. Neither the Hodgdon website nor any of my manuals give suggested powder weights for that weight of bullet. I am using H4198 (I know that it's not the best powder for a .223 but it's the only one I can get). Does anyone know what would be a good powder weight to start working up a load? I am shooting a Bushmaster with a 24" barrel with 1-9 twist.

Thanks.
Historian

 

[steve4102]

Use Hodgdon's Sierra 63gr data. As always, start low and work up.

 

[BullfrogKen]

4198 is much more geared towards the lighter bullets in a .223, 55 grains and below.

 

[rcmodel]

Yep!

Too fast burning for that heavy bullet in a gas gun.

It may work, but may have to push the pressure envelop to get enough gas-port pressure to cycle the action.

I'd look for lighter bullets, or a different powder more suited for 63 grain bullets.

rc

 

[243winxb]

H4198 in Ar15 223/5.56

It is true you wont get maximum velocity with heavy bullets. I have used IMR 4198 in many different firearms, worked OK. Only 1 time i know H didnt work - http://www.thehighroad.org/showthread.php?t=502784 The gas port pressure curve is a critical part of internal ballistics for cartridges used in gas operated firearms. Gas operated weapons are generally tailored to a narrow range of powder burning rates and characteristics. If the port pressure is too low the weapon will fail to function and if to high the weapon may function too forcefully or rapidly causing extraction or cycling problems. When using the fast H4198, the pressure peaks very fast and is done producing pressure sooner than your slow powders. With such a wide range of bullet weights from 40gr to 80gr, matching the gas port location and size is critical.