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IMR4350 vs H4350
- Thread starter montana09
- Start date
ligonierbill
New member
Pretty close, but if I switched from one to the other, I would redo the load workup. If you have a good load for one, run out of powder and can only find the other, your workup should come out fairly close. But interchange them directly? I would not.
I've used both and will get virtually the same velocity and accuracy with slightly different powder charges. The data isn't interchangeable, but close.
A max load of IMR4350 is one grain more than a max load of H4350 with 165 gr bullets in a 30-06 according to my manuals. It could be slightly different in another manual. They show H4350 with a 4 fps advantage, which is nothing.
I prefer H4350 because it is more stable under a wider range of temperatures. And that is the only reason. Most powder, including IMR 4350 will see 2-3 fps velocity change for each degree temperature changes. H4350 is closer to 1/2 fps for each degree temperature changes.
If you develop a load at 70 degrees and fire it at 20 degrees IMR4350 could be 100-150 fps slower. H4350 would only be about 25 fps slower. That is the only real difference.
A max load of IMR4350 is one grain more than a max load of H4350 with 165 gr bullets in a 30-06 according to my manuals. It could be slightly different in another manual. They show H4350 with a 4 fps advantage, which is nothing.
I prefer H4350 because it is more stable under a wider range of temperatures. And that is the only reason. Most powder, including IMR 4350 will see 2-3 fps velocity change for each degree temperature changes. H4350 is closer to 1/2 fps for each degree temperature changes.
If you develop a load at 70 degrees and fire it at 20 degrees IMR4350 could be 100-150 fps slower. H4350 would only be about 25 fps slower. That is the only real difference.
+ 1 Old Roper
H4350 velocity changes about 12 - 15 fps over the range of 0 to 125 degrees F.
IMR4350 velocity changes about 155 fps over the same range of temperatures.
On a normal summer's day at our range, temperature in the shade changes on the order of 20 - 30 degrees from 8 AM to mid-day.
That equates to a max of 3.6 fps increase for H4350 or 37.2 fps for IMR4350.
Some of the extreme powders perform even better than that.
H4350 velocity changes about 12 - 15 fps over the range of 0 to 125 degrees F.
IMR4350 velocity changes about 155 fps over the same range of temperatures.
On a normal summer's day at our range, temperature in the shade changes on the order of 20 - 30 degrees from 8 AM to mid-day.
That equates to a max of 3.6 fps increase for H4350 or 37.2 fps for IMR4350.
Some of the extreme powders perform even better than that.
ligonierbill
New member
Yeah, Nosler 8 lists only IMR-4350 for their 140s. Oddly, the next page of 150 loads lists H4350, but not IMR.
Anyway, I checked Quickload. Setting the case volume on QL to match the velocity Nosler got with their 140 gr IMR-4350 max load (52.5 gr./2,858 fps), I changed the powder to H4350, same charge weight. QL projects 350 psi pressure decrease and 6 fps velocity decrease, essentially the same. As always, work up slowly.
Also, compare this to Nosler's 150 gr H4350 max load of 52.0 gr. Pretty close. Have fun.
Anyway, I checked Quickload. Setting the case volume on QL to match the velocity Nosler got with their 140 gr IMR-4350 max load (52.5 gr./2,858 fps), I changed the powder to H4350, same charge weight. QL projects 350 psi pressure decrease and 6 fps velocity decrease, essentially the same. As always, work up slowly.
Also, compare this to Nosler's 150 gr H4350 max load of 52.0 gr. Pretty close. Have fun.