Are the burn rate of these two powders similar? I am trying to work up a load for a 280 Ackley and have been very happy with H4350 in other calibers but the load data I have found is for IMR4350. Could I use the IMR data for the H4350? I am fully aware of pressure signs to watch out for, but for a starting load, are the 2 interchangible? Thanks

Thanks Bigdaddy. That is pretty much what I though, but I just wanted to check. Thanks again!

Good advice from Bigdaddy. I find more and more uses for H 4350, it is good powder.

R F

I have a can of each and from what my chrono tells me they have been real identical in making velocity. H 4350 has not been showing me a slower velocity. I would have to think pressure has been real identical too. BUT you have to remember that these are two individual lots and it's possible that lots can vary by 5%--so maybe my IMr is a hair slow and my H is a hair fast. At any rate for my purposes I would not load H4350 with any more grains than I4350 as some data suggests.

Hi tlp335. I've used these two powders quite a bit in my 300Win mag, 25/06, and in my 270Win. I've always found H 4350 to be about 2grs slower than IMR4350. In fact I've found it to be between IMR4350 & IMR4831. A very useful powder in a variety of calibers.

Faster to slower:
176 IMR-4350
177 H-4350
178 S-365
179 TU-7000
180 N-550
181 AA-4350

ric--posted the order=imr4350 than h-4350, you can usually use 1-2 more grs of h-4350. Imr will show more signs of pressure faster before you reach the higher vel. with that powder. Imr 4831 and Imr 7828 are also excellent in that cal.

Been using IMR4350 in my .257 Wby Accumark for years. Loaded at 3300 fps as per the Hornady manual (58.8 gr) for a 87 SP bullet, I've gotten a best grouping of .5 MOA at 100 yards.