H4895 vs. IMR 4895

[Sam Adams]

I've recently come across some data for the mil-spec loadings of various .30-06 and 7.62 x 51 rounds. Many of these use IMR 4895 as the powder. I have none of that, but a fair amount of H4895.

You can see the question coming, can't you? Can they be used substantially interchangably from the standpoint of both safety and accuracy, or should I just load up my H4895 to the same/similar velocity as the mil-spec loads.

FYI, I am specifically trying to duplicate the M118LR (which uses SMK 175 bullets) and M852 (which uses SMK 168 bullets).

 

[USSR]

Sam,

They're close, but not the same. I use alot of surplus IMR4895 in both .308 and .30-06. In .308 using LC brass, H4895, and 168-175gr bullets, I would start at 40.0gr and work towards 41.5gr while looking for pressure signs.

Don

 

[Hunter0924]

The data from IMR 4895 and H4895 is not interchangeable.

 

[GooseGestapo]

They're very similar but not the same.
However the difference is about like the lot-to-lot variation I've seen within make/brand.

Start 5% low and work up, same way you should with a new lot#.

I have a distinct preference for the H4895 due to it's stellar performance in the .30/30 and .35Rem. (somewhat slower in these applications than the IMR variety).

 

[Linear Thinker]

They used to be same when Bruce Hodgdon got started in the business selling WW2 surplus 4831 and 4895 in grocery paper bags.
Since the surplus stocks ran out decades ago, H4895 has been manufactured under contract by various makers, ADI in Australia last I checked. Likewise, IMR4895 hasn't been made by DuPont since the Delaware factory fire, and is made in Canada under contract.
They are very close in burning rate, but not same by volume/weight.
So, don't substitute. I prefer Hodgdon's since it has been 10-20% less expensive than IMR. I use it for 250 Sav, 30-06 and 7.55 Swiss, and love it.
Your rifles may have a preference - get a chrono, find out which is better for your needs. That's the fun of handloading!
LT

 

[fineredmist]

H 4895 and IMR 4895 are chemically identical BUT the finish coatings which effect the burning rate ARE NOT THE SAME. You must approach this extremely carefully if you insist on doing so instead of spending $20 +/- for a pound of the correct powder.

 

[Sam Adams]

Thanks, all. I suspected that they weren't identical (though close), and I certainly WON'T use the data interchangably. What I will do is find the amount of H4895 that matches the IMR 4895 data, then (if it is safe in the load books) bump it down by 5% or so and work my way up carefully.