IMR 4064 temp sensitive?


January 23, 2013, 10:23 AM
I've heard that H4895 is one of Hodgdon's "extreme" powders and is not temp sensitive. Its frigid today but I'm off so I'm trying out a bunch of reloads for the .243 and .308 using both H4895 and IMR 4064. Is IMR 4064 sensitive to temp changes? I mean if I zero my scope to a load charged with 4064 at 25 degrees will the zero be off when I shoot the same load at 90 degrees?

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January 23, 2013, 12:00 PM
I'm currious about this as well. Almost bought some Varget the other day since it's touted as being temp insensitive.

January 23, 2013, 12:06 PM
thomis, I think any rifle powder is sensitive to temperature change. The reloading manuals say that velocity can be decreased as much as 5% or even 10% as temperature is decreased from say 90 degrees down to 20 degrees. I have heard of powders that were not as temperature sensitive but when I look up the loading data they didn't develop the initial velosity that is available from the standard powders. I shoot in the summer at 90 degrees and during the winter as low as 20 degrees and I notice the difference. At 20 degrees you may have to raise your point of zero a click to compensate for the point of impact change. I have not noticed IMR 4350 or IMR 4895 to be hard to ignite at low temperatures, but I do load magnum primers with IMR 4064 to get the best result.

January 23, 2013, 12:58 PM
The other thing you need to consider an ice cold barrel will shoot to different impact then warmer barrel because of the harmonics. Thinner barrels more so than heavy or Bull barrels. Crony the loads off a cold barrel and cold shells then warm gun and check your FPS and impact, THEN TAKE YOUR RIFLE and shells put it on the dash board of your vehicle crank up the heat and with a warm case and bullets in warm pocket run back to bench and see what happens?
This will give a ball park idea without waiting for 90 degree day.

January 23, 2013, 04:13 PM
IMR4064, yes.

I shoot a lot of it and it does vary a little.

H4895 and Varget vary less but the 4064 is fantastic in my 308 so I adapt.

January 24, 2013, 01:45 AM
Great timing, as I just happened to be reading Hodgdon's website earlier today regarding their "Extreme" line of powders.

The 3rd graph down shows a 46 fps extreme velocity spread for .308 between 0-125 deg. F.

I'm currently using IMR4064 in my .308 hunting loads, but may try some Varget in the near future. It's usually not too cold where I hunt, but I'd rather have as little variance as possible.

I'm also shocked at the velocity spread with IMR4895. I knew BL-C(2) is temp sensitive, so it makes sense that Win748 would be, but I thought IMR4895 was a popular powder with the high power shooters. You think they would have complained about that much variance, especially during summer competitions.

January 24, 2013, 08:00 AM
Depending on where you live this can be a big deal. It can mean about 1 fps difference for each degree of temperature change. A load I develop now, could easily be 75-80 fps faster in August. Most guys are concerned about the load being slower in cold temps and it hitting low at long ranges. I'm more concerned about a load that is safe in winter being over pressure in hot weather.

That is why I switched over to Varget for my 308 and H4350 for my 30-06. I had previously used 4064 and IMR-4350. I had to develop new loads, but I'm getting very good speeds and accurcy with the hodgdon powders vs the IMR's.

Mike 27
January 24, 2013, 11:00 AM
I have been using it for years in Alaska, and I am sure it is but not enough that I have noticed much of a change in my 30-06. I love the stuff, very accurate.

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