Home Forums Reloading Big Game Rifles Just how Temp Sensitive is IMR 4350

Good one.


fish head

I know I shoot H4350 mostly, its just that I have a bit of IMR4350...

I'm thinken you need a 338 for that chili, or maybe that is just wolf brand chili.

with a drop in velocity of 155 fps at the Muzzle, have you checked out a ballistic chart and seen what change in trajectory that would have at 200 to 250 yds???

for deer hunting that would be immaterial..

especially when deer are usually taken at less than 100 yds, much less than 200 yds..

1 or 2 clicks on the scope adjustment would more than compensate for any potential trajectory drop at 200 yds...

Sheer velocity loss is not the major problem. Quite often a velocity loss of 150 fps is accompanied by a significant change in point of impact, even at 100 yards.

Most of us have seen this when working up handloads with varying charges of powder. Quite often the difference in point of impact between starting and maximum loads witll be several inches at 100 yards, though the difference in muzzle velocity is only, oh, 150 fps.

This is what can happen at colder temperatures with a powder that loses considerable velocity. I have done a lot of testing of various loads at temperatures of around zero F., using the same rifles and loads that were sighted-in at 70 degrees or so.

Often (but not always) point of impact will shift 3-4 inches. It doesn't always shift up and down, but can shift side-to-side as well. For instance, one .270 load I tested landed 3" to the right at zero degrees, after the same load was sighted in at 70 degrees. That would mean a shift of around 8" at 250 yards, certainly enough to cause problems on a deer.

The only way to find out if this might happen with your rifle and load is to shoot the rifle at colder temperatures.

However, I have tested a lot of loads using Hodgdon Extreme powders, and have yet to see any major change in 100-yard point of impact. This doesn't mean it can't happen, but I haven't seen it.

That is the bigger problem with velocity loss point of impact can change significantly.

I have also experienced loads that when first tested in higher temps were solid 3/4MOA loads and when they were shot at temps in the teens the groups opened up to around 3" and POI shifted 3-4 inches as well.

And this is the main reason I have gravitated towards the Extreme powders in recent years. Though, in a couple of instances, accuracy was better with the IMR powders, the consistancy in the point of impact was as important of a component of my accuracy requirements as group size, and a slight compromise in raw accuracy was worth the peace of mind.

Yes I know, and I was just wondering if an 80-10 degree swing would make that much difference. Many of the studies here are 70 down to -20 or something. I wanted to try and use some powder on hand but what the heck...I will just use the H4350, and buy a pound of RL17 and H100V as well.

I guess I will use the IMR4350 for tomato fertilizer.

Here is how Hodgdon says H4350 compares to IMR4350 for temperature variation from 0 to 125 degrees.

I haven't tested IMR-4350 against H-4350 but I have tested H-322/H-4198/RL-7 and Benchmark in 75 degree's and 45 degree's with "No" noticeable difference..They all dropped in velocity..

One reason I load my hunting loads/bullets at hunting temps and keep separate from the play rounds/bullets..

Jayco

Have not tested the last 2 in that chart but on the first 3 I know that they are completely full of schit.

53gr of IMR4350 under a 100gr TSX in my .25-06 lost no noticable velocity when going from 30 deg C to -10 deg C. I agree with Mule Deer, you've gotta test your rifle and your load in different temperatures to know if it's gonna lose velocity and/or change POI, or not.

Just now contemplating the same thing. I Recently fired five loads in my .300 WSM using both H4350 and IMR4350 with 180 grain TTSXs (3 shot groups at 100 yards).

With H4350, the smallest group I had using H4350 was 1.05" and the largest group was 1.59" (average for the 5 loads was 1.38").

With IMR4350, the smallest group was .53" and the largest 1.20" - the three other groups were all MOA-Sub MOA (average for the 5 loads was .98"). Was very excited, the first time I've gotten so many MOA groups with a single powder.

HOWEVER, the POI with each IMR4350 was clearly different for each load (i.e., would need a seperate sight in depending on the load). With H4350, the POI was virtually the same across all five loads - in fact if I remember correctly, the 15-shot group would measure 2.10" (with IMR4350, the 15 shot group would measure close to 4").

I will re-shoot the H4350 - due to my unfamiliarity with my Uncles ancient vernier caliper (no dial), I mistakenly seated the bullets with the H4350 at .086 off the lands (I have standardized my tests loads for the 180 TTSXs at .050 off lands). I am hoping this will give better results (at the worst, it will provide fairer comparison of H4350 with IMR4350).