IMR4350 vs. H4350 (Missed Coyote!!!)

iceman2 said:
It happens, that is why it is called hunting and not shooting.
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I'd be more inclined to say that when its time to shoot, the hunting part is over. Now all that counts is marksmanship, and on a live target, you have to get it right the first time.

I made a classic beginner’s mistake last week end. I had a shot at a beautiful wolf. The set up was perfect, it was a dull day so there was no glare, the air was still, it wasn't snowing, the wolf was broadside, and I was shooting from a good solid position with my iron sighted .30/06. The problem was he was a hair closer than I estimated. I held the front sight just over his back, expecting a 300 yard shot, and yup the bullet went right where I aimed, over his back. So did the 2 follow up shots . . . then he was gone.

Message to self, when you aim at air, you’ll hit air! So the problem wasn't with the hunting part, that worked out right well, it was the shooting part, that was the problem, and marksmanship includes range estimation. Turns out he was between 230 and 250 yards away . . . and he's probably still running.
 
That is a pretty big temp difference which means lower vel. and more drop.
Also not sure of the set up of your firearm but on my MilDot at 1/2 power
(12.5) a 300 yd shot requires only about .65 of a mil.

A 1 mil holdover would have me long at 300yds by about 55-65 yds.

I bet it was more a miscalc than your marksmanship.

cheers

PS I shoot a .243 100gr zeroed at 37 degF, 64% humidity, 820 ft, 30.343 Baro and 200yds
 
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It's time to take the rifle out the to range and see exactly what's happening. Ofcourse, hunting and the range are two different beasts. Thanks for the insights and suggestions all...
 
I recommend Maj Plaster's excellent book on sniping for the most informed discussion of wind I have read. Most folks feel a wind, or see one indicator, and judge windage accordingly. Plaster explains why snipers are not truly one shot- one kill guys.

On a square range, there usually are wind indicators, and one a range you are familiar with, you learn which indicators mean what. In the field there are no indicators, just shooter observations, and an attempt to evaluate what those observations might mean. Get it right, and compensate, and you get a hit. Misread those waving trees, that flagging grass, ignore the slope behind you, or behind your target, and y voila, the actual wind experienced by the projectile in flight is not what you thought, and gee, the powder must behave differently in different temperatures! A 30 km wind will take a bullet off Wiley at 300 yards, and if the OP discounted the wind because where he was it was on his back, well, ther yuh go.
 
wow .. you sure put a lot of thought into this miss. As long as I have another day to shoot and lots of ammo I'm happy....however I do throw out the odd s*$t, crap, F*$%^r when I miss. Sometimes nature wins .... and sometimes my wife shoots better than I do. I really wish I could explain that.

My guess is that used one of those powders you referenced without playing with a target or two. The two powders are not interchangeable data wise!! Otherwise nature won ... it happens to the best of them!!

Wind, angle of aim, temp and humitidy can also affect accuracy ... if you really want to twist your brain around it. My experience, going from 30 to -5 doesn't make a noticeable difference with the powders I shoot. The most common reason for me to miss to bullseye is ME!
 
temp and trajectory

There is an effect of temperature on trajectory, but I don't think it is completely explained by powder.

From what I have read, the general rule of thumb is a 1 MOA drop for every 10-11C drop in temperature. This increases past about 600 yards

No doubt, powder selection plays a part, but it isn't the whole story. Something else is going on. That said, I don't know what the other factors might be.

I seem to remember articles from Millet, Berger bullets, and some sort of Australian SWAT team evaluation.

Sorry, don't have the links right now - but Google is the way I found 'em, you can too.

Fat
 
fat but funky said:
From what I have read, the general rule of thumb is a 1 MOA drop for every 10-11C drop in temperature.
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Hmmm, I'll have to take a look at this-if that's true, that would be 9" at 300 yds (35 C range/11 C = 3 MOA). That's quite the drop-that's why I was looking at moving to a temp stable powder like H4350. Plus IMR 4350 is similar in burn rate to H4350 for quick load development/convert over.
 
You mean you didnt sight in at the temps you intended to shoot at? Seriously, you've had enough internet therapy, go out and shoot the rifle at 300 y with a strong wind and see what happens.
 
To the original question, IMR vs H powder. I switched to H 4350 for the same temperature problems with IMR4350 (wide temp/velocity swing). I found my load wieghts slightly different when switching. I have used the H4350 at 38C and down to -28C it handles the temp swing very well. The change in trajectory due to humidity and air pressure still play a factor due to the tempurature swing, but the more variables you remove from the equation on the longer shots the better, and I don't think anyone will argue that. I sight hunting rifles in at a lower temp to help with this also.:)
 
the websites I was referring to earlier

http://longrangeshooter.com/2009/02/temperature-effects-on-zero/




http://www.millettsights.com/resources/shooting-tips/mathematics-for-precision-shooters/

the temperature bit is about 2/3 of the way down the millet page


Sorry, can't find the one Berger now

Fat
 
I did some testing with rl22 in my 257 wby a few years back. Between +25 and -25 I lost ~250 fps. Groups also went from .5" to 2.75" when the bullet slowed down. I use h4350 h1000 and retumbo in all my gums now because testing has shown me that they are very stable between summer and hunting temps.


I did these tests to ensure that when it's -20 and I'm hunting I know where I'm going to hit since we all do our load dev when the weather is nice out.


I also load for a buddy who has 10 lbs of old imr 4831 and he lost 170 fps between summer and winter with that powder in his 280 rem and 150 pt/btips.
 
rem338win said:
It dont work like dat.
They are not interchangable. H4350 is historically slightly slower burning.
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I think he was just saying that he's using temp stable powders (H###X) to reduce velocity differences at wide temperature swings. I chose RL-15 for 22-250 because apparently it's temp stable. When I started reloading, I had no idea that temperature could affect POI-much the wiser now! :dancingbanana:
 
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