IMR4227 a replacement for H4227

[320pf]

Hodgdon has discontinued their version of 4227. I talked to a Hodgdon ballistic engineer and was told that H4227 and IMR4227 are very similar powders and will give similar results. The difference column below seems to bear this out.

Here are the results of the comparison of IMR4227 and H4227 with the 300-221 fireball (a.k.a. 300 whisper).

First H4227 is slightly more dense that IMR4247. The powder dispenser set to throw 18.5 g of IMR4247 would throw 19.0 g of H4227.

Here are my load/velocity data from a 16-inch Noveske barrel with the gas port in the pistol postion. The bullets used are Winchester .308 147g FNJBTs. These data were shot with CCI450 magnum small rifle primers

H4227___________IMR4227______difference (H4227-IMR4227

16.0= 1869±20 ____ 1835±22 _____ +34
17.0= 1967±13 ____ 1968±7 ______ -1
18.0= 2037±41 ____ 2043±19 _____ -6
18.5= 2076±22 ____ ** ___________--

**chrono malfunction

Here are some more results for H4227 that I shot about 2 years ago. These data were shot from an Olympic Arm 16-inch barrel with the gas port in the pistol postion. The bullets used are Winchester .308 147g FNJBTs. These data were shot with Winchester small rifle primers. I seems that the different barrel and primer combo had little impact on the velocity results as well.

H4227 Olymp barrel_________H4227 (CCI450 primers/16-in. Noveske barrel)
Winchester SR primers______________ difference

16.0= 1871±18______1869±20______ 2
17.0= 1940±6_______1967±13______ -27
18.0= 2013±17______2037±41______ -24
18.5= 2087±19______2076±22______ 11

17.5= 1990±10,
______1995±9,
______1984±17

In conclusion I would say that IMR4227 is a powder worth considering.


320pf