IMR 4451 Powder

By Al Voth on July 26, 2016

It’s no secret that a large chunk of competitive rifle shooting is done with mid-sized cartridges. The 308 Win. is a classic example; as are all the cartridges which have spun off of that case, including one of my favourites, the 260 Rem. These cartridges all have relatively mild recoil, great accuracy and are relatively cheap to shoot. One of the classic powders handloaders use for these mid-sized cartridges has always been H4350. Unfortunately, it so dominates the popularity charts that it seems to be perpetually out of stock at retailers.

Many shooters are experimenting with substitutes for the scarce H4350, and IMR 4451 seems to be rising to the top as a good alternative. Having heard several good reports about the performance of this powder, when the opportunity arose to score an 8 lb. jug of it, I quickly parted with the necessary cash. So far, I’ve tried it in a handful of calibres and like most handloading components, I’m finding some guns like it and others don’t.


Announced in the fall of 2014, IMR 4451 is part of a line of powders IMR has labelled as featuring Enduron Technology. Simply put, this means these powders have small kernels for easy metering, are not sensitive to temperature changes and have a built-in copper fouling eliminator. And it was that last point, which caught my attention, as I have a couple of rifles in the vault, which I really like, but which tend to copper-foul badly enough that I think twice about shooting them.

Chief among those is a Weatherby Vanguard 2 in 270 Winchester, and for me it’s there that I’ve had the most encouraging results with IMR 4451. With ??? grains of powder behind a Hornady 130 gr. SST bullet I’m getting 3150 fps and five shot groups averaging in the 0.800″ range at 100 yards. That’s great performance from a hunting weight rifle and I’m now looking forward to some colder weather to confirm the powder’s ability to produce consistent velocities across temperature extremes.

The copper fouling which was the nemesis of this rifle, is now under control and it takes significantly less effort to clean. I do notice there is more carbon-like black fouling to deal with during cleaning, but this is much easier to remove than copper, and I find it’s not a chore. This is unusual, as I haven’t noticed this extra powder fouling in any of the other rifles I’ve tried IMR 4451 in. Although, it’s ability to deliver on the promise of less copper fouling is clearly evident in each of them.

So far, I haven’t found an accurate enough load of IMR 4451 to replace the H4350 recipe I have for those other rifles, but the search will continue. As always, it’s not just powder that can be hard to find; there are no Sierra 130 gr. TMK’s available locally either. But I have some on order and as soon as those show up IMR 4451 will get a serious try in a 260 Rem. as well. In the meantime, IMR 4451 gets a thumbs up from me as a good potential alternative for the hard to find H4350.