IMR4350 vs. H4350

[sticknstring]

I have a 257 wthby that I am starting to reload for. Looking at the manuals I have, I found several IMR4350 recipes. I do not have the IMR on hand, but have a pound of H4350 on hand. To my understanding the IMR is slower than the H powder. Could I use the H that I already have safely?

[Spuds]

Hodgdon has H4350 data for the 257 on-line Basic Manual Download.

[green 788]

In my experience, IMR is *faster* than H4350.

go to Hodgdon - The Gun Powder People to find their data for both powders...

click on "data," I think it is... you'll find it

[Mikecr]

I think it all changes from lot to lot.
So,, what does '4350' mean anyway?

[lloydsmale]

personaly id be looking at a slower powder if you want max velocitys out of the 257. At least as slow as 4831 and even that in my opinion is a bit fast.

[JackinSD]

Originally Posted by lloydsmale

personaly id be looking at a slower powder if you want max velocitys out of the 257. At least as slow as 4831 and even that in my opinion is a bit fast.

Might want to check your data. According to Hodgdon reloading data center, the 4831 will not quite reach the speeds of the 4350 in any bullet weight.

H4350 looks like it will do just fine, in the velocity area for the range of 257 weight of bullets. There are a couple others that beat it in one or two bullet weights, but overall H4350 does pretty well.

[lloydsmale]

well jack all i can post is facts that came from actualy chonographing my loads running powders to the point that pressure signs start developing then backing off a bit. In my experience the 257 is a bit overbore for powders as fast as 4350. Also id look at the pressure that manual gives for that 4350 load then compare it to the pressure for the 4831 load and id bet there loading 4350 to a higher pressure to beat powders like 4831, 7828, re25 ect. Run those powders to the same pressure and see what you get.