IMR 4831: temperature and velocity loss

[Strawberryridge]

Hey all;

with an upcoming late season elk hunt with my father in Wyoming, Im trying to figure out what kind of velocity changes I may get with IMR 4831 going from summertime 85 degree shooting to hunting in colder temperatures (unlikely to drop below 20 degrees or so, unlikely higher than 50 degrees). Ive chrony'd the numbers in the past, but cant figure out where I wrote them down. It seems like the velocity loss wasnt significant, maybe 50-75 fps, but I wanted to hear other thoughts... POP, I know you're from Wyoming too, you should have these kinds of numbers handy (grin)...

7mm Rem mag
Federal 215
65g IMR 4831
150 grain Ballistic Tip
3197 fps (avg), (E.S. 12 fps)

I know, I know, someone will say the Ballistic Tip isnt for elk... Thanks.... It will work just fine for its intended purpose. 'Preciate the thought though...

 

[Richracer1]

I know, I know, someone will say the Ballistic Tip isnt for elk... Thanks.... It will work just fine for its intended purpose. 'Preciate the thought though...

I don't know why some would say a B-tip isn't for elk, but I do know that if it impacts an animal above 3000fps it'll react like a varmint bullet - meaning it explodes instead of expanding.
Impact below 3000, your good to go, works like it's suppose to, if you the shooter did your part for placing the shot.

 

[FOTIS]

With IMR powders I have noticed a bit variation from cold to hot. Older lots (10 years or more) of IMR 7828 had given me more than 100 fps variation. With the newer lots I really do not know that much. I use Hodgdons and Alliant powders almost exclusively.

Remember though all are owned by Hodgdon now.

Place your shots carefully with that BT or try a tougher bullet.

 

[jdmason480]

Hey all;

with an upcoming late season elk hunt with my father in Wyoming, Im trying to figure out what kind of velocity changes I may get with IMR 4831 going from summertime 85 degree shooting to hunting in colder temperatures (unlikely to drop below 20 degrees or so, unlikely higher than 50 degrees). Ive chrony'd the numbers in the past, but cant figure out where I wrote them down. It seems like the velocity loss wasnt significant, maybe 50-75 fps, but I wanted to hear other thoughts... POP, I know you're from Wyoming too, you should have these kinds of numbers handy (grin)...

7mm Rem mag
Federal 215
65g IMR 4831
150 grain Ballistic Tip
3197 fps (avg), (E.S. 12 fps)

I know, I know, someone will say the Ballistic Tip isnt for elk... Thanks.... It will work just fine for its intended purpose. 'Preciate the thought though...

Even though you professedly don't care, you did come here seeking advice. There is absolutely no good reason to use a BT over an AB especially with 7mmremmag velocities.. I've experienced complete failures of the BT on ANTELOPE through my 7remmag on two occasions one of which was directly behind the shoulder at 200 yds hitting no bone other than ribs.

Can't afford $23 dollars for a new box of 160gr AB's? Or, do you enjoy torturing animals before you kill them?

 

[jtoews80]

There are 7mm 160 grn AB's on sale at the SHooter's pro shop for 11.95/50 but the tip isn't the right color. I will not touch the application issue, as I've never shot an elk and haven't used Nosler bullets from a 7mm for hunting purposes yet either.

CC.

 

[Strawberryridge]

To all,

obviously you've all displayed some concern for using the Ballistic Tips. I appreciate that, and I believe its decent advice for passing along to someone whose experience with elk is limited. However, I am not new to elk hunting. Theres a few pickup loads of bulls that will attest to that. So while youre concerns are valid to a small degree, Im not looking to debate bullet capabilities or usefulness. I just wanted to know about the temperature/powder question...

The 160 Accubonds actually do not shoot quite as well at distance as the ballistic tips, and Im a fan of accuracy, not hitting and hoping. From everything I have experienced, those 150 Ballistic Tips are actually very tough bullets and will go quite effortlessly through the ribs of most anything Wyoming can offer. So, as I said in my post before, they will work fine for the intended application.

jdmason, not to disappoint, but I didnt come for advice, just wanted to know if anyone could answer my question since Id misplaced my shooting notes. But Ill have to admit, guys like you really make a good site like this one seem less appealing. I dont need your approval and you dont need mine. If you have something positive to add, great. If not, why even type? Im new to posting (but not reading) here and not looking to ruffle any feathers, so please, lets not sling ethical mud. Its not good for either of us. :roll:

Thanks for the replies...

Strawberry

 

[remingtonman_25_06]

"There is absolutely no good reason to use a BT over an AB especially with 7mmremmag velocities.. I've experienced complete failures of the BT on ANTELOPE through my 7remmag on two occasions one of which was directly behind the shoulder at 200 yds hitting no bone other than ribs."

I have to disagree. The 7 Mag is fast, but it aint that fast...The NBT is a solid performer when the bullet impacts at 3000fps or below. Take the 140g NBT for example, load it to 3250fps and by the time it gets to 100 yards, its slowed down to around 3050fps which is perfectly suitable for the given task at hand. With an antelope, this is very hard to believe a failure at 200 yards. I happen to own a 7 RM and use the very same 140g NBT's I speak of and have had no problems. Infact I've had nothing but DRT kills and complete passthrough's on every deer its connected with.

One good reason is this. Look how many elk were killed before all these bonded bullets started popping up. Elk dont know any different from now or 40 years ago...In all my tests, the NBT out performed the famed Remington core lokt in penetration and weight retention. How many elk have been killed with the corelokt? I've seen more then 15 elk shot in the last 5 years or so with 180g NBT out of several 300 Win mags from 50-750 yards with no problems.

On a sidenote, did you kill both antelope? What was the other "failure."

 

[big rifle man]

jdmason480, I'm not going to add any other technical comments to this post other than to say your advice is sound. Having hunted elk for over 30 years and deer for much longer than that I've had the opportunity to use both the old and new in bullet design. I've seen what a BT can and can't do and suggest that an Elk deserves a better constructed bullet. I know there's people on this forum that will strongly disagree with my comments but there are a lot of things to take into consideration when hunting elk as opposed to deer. Elk can be dropped with a .22 so I guess that makes it OK for hunting Elk.

 

[FOTIS]

"................ The 7 Mag is fast, but it aint that fast...The NBT is a solid performer when the bullet impacts at 3000fps or below. "

I totally aree with Remmy when the BT's are used within these parameters. :wink:

 

[jdmason480]

I may have overstated my case. My apologies. I'm a little passionate about hunting.

By "failure" I meant that the two bullets in question disintegrated on impact. Both animals died quickly as they would if hit with bird shot out of a 12 gauge at close range. My point is that if the bullet were intended to shoot anything other than varmints, it failed in its performance on these two occasions. If either shot had hit the shoulder of an elk, or maybe even the antelope that they killed, it could very likely have resulted in irretrievable wounded game. Even though I've never shot anything other than a Nosler bullet at big game in 30 years of hunting, I would have changed manufacturers had the AB not come out.

Impact velocities were below 3,000 fps in both cases--approximately 2,700 and 2,400 respectively.

One's specific gun may "prefer" a 150 gr BT to a 160 gr AB, but I defy anyone other than a professional sniper to record the differences at hunting ranges across a variety of guns.

The game we take deserve respect and I do not believe that BT's afford them that.

Happy hunting!

 

[baltz526]

i really doubt you will lose any real velocity, your point of aim might change. PS: ballistic tips are good elk bullets. you should see what happens when you hit an elk through the chest with a 120gr 7mm at 3400fps impact velocity

 

[R Flowers]

I was testing some loads in my 25-06 a couple of years ago and it seemed I was getting lower velocities than expected with IMR 4831. I elected to do a little informal test.

Statistically, these tests mean nothing, the sample size is to small to be valid, but they told me what I wanted to knkow.

I loaded shells with a variety of powders. I then put half of them in the freezer overnight and left the other half sitting on my loading bench. In the morning the frozen shells were put in plastic sandwich bags and placed on ice in an ice chest. I then went to the rifle range and proceeded to chronograph the loads.

The first day I tested the ambient temperature was 80 degrees. The ambient temp shells for each load were shot first, the gun was allowed to cool completely, then the frozen shells for that load were fired. Interesting results:

The frozen shells loaded with IMR 4831 lost 68 fps.
The frozen shells loaded with H 4350 actually gained 43 fps!!
The frozen shells loaded with H 4831SC gained 23 fps.

I was intrigued so I tested some more. On this day the ambient temperature was 76 degrees F. Much the same results:

The frozen shells loaded with IMR 4831 lost 65 fps.
The frozen shells loaded with RL 22 lost 34 fps.

I did much the same thing with a 300 Winchester Magnum a number of years ago. To my surprise, shells loaded with old surplus H 4831 also gained around 20 or 30 fps when frozen.

Have I given up on IMR 4831? No, it still shoots so good in my 25-06 that I am still loading it.

 

[Strawberryridge]

R Flowers,

now thats the kind of info I was looking for. Many thanks! I was thinking of doing something similar (freezing the ammo), but was unsure what kind of effects you would get shooting 25 degree ammo out of a gun thats been sitting in 85 to 90 degree heat. Ill give it a try for myself though. Again, thank you...



Strawberry

 

[phutch30]

Huh I did the same freezing the shells thing with my 7mm loaded with imr4831 (63 grs) I didnt have anywhere near the velocity loss you did. Interesting. I only lost about 5 fps average. I didnt let the barrel cool completly though. Maybe that affected my results.

 

[kiddekop]

For cold weather(coolest was 40 below in november, most nights were -15) hunting trips in CO I switched to mag primers in my Sakos in 300wm & 30-06 ammo using IMR 4831 with 180gr sierra gamekings.I also used nosler solid base 165gr bullets.I have a friend who uses 165gr nosler solid base bullets(he has a large supply) in his 300 weatherby mag with IMR 4831 for black bear,mule deer & elk.

 

[corbin9191]

Strawberryridge, I also live in wyoming and shot at different temp's and I havent really had a big problem with IMR 4831. Last year I sighted my rifle in at 3 inches high at 100 yards with a 270 win at about 68 degree weather and when I went into the bighorn mountain for my elk hunt there was about 10 inches of snow on the ground and the thermometer read about -15 degree's. When I finally found my elk he was around 450 yards. And I held my scope right where I was supposed to and nailed it behind the front shoulder where I wanted it to go. But I didnt have any problems with this powder.

 

[Colin]

Here's a thought for Mason....

On my last antelope hunt, I used my .25-06 and handloaded 110gr. Accubonds. I shot my buck at 185 yards. I hit him high (in the spine) and he dropped.

My buddy shot his buck at 235 yards with his 7mm-08 with handloaded 140gr Ballistic Tips. His buck ran probably 1/2 mile and layed down, needing a finishing shot.

Looking at my buck, the wound channel was pretty small. Yes the buck dropped, yes he died. No the bullet did not fail, however, because of this I will be choosing a Ballistic Tip next time, as I feel the Accubonds are a little too tough for the light skinned Antelope.

Looking at my buddies buck, his 140gr BT entered perfectly behind the shouldertaking out one lung, severing the esophogus and exiting the neck in front of the off side shoulder. The wound channel was massive.

Now looking over the very basic details, my buck dropped and died faster than his. But this does not equal a better or worse bullet.

Hunting is an imperfect sport. Suggesting that those whom do not take your advice do not care as much about the animals they hunt is a very slippery slope, my friend. We should pass on our knowledge in the field to help others, and not get our feelings hurt if they don't take our advice.

 

[Colin]

Here's a thought for Mason....

On my last antelope hunt, I used my .25-06 and handloaded 110gr. Accubonds. I shot my buck at 185 yards. I hit him high (in the spine) and he dropped.

My buddy shot his buck at 235 yards with his 7mm-08 with handloaded 140gr Ballistic Tips. His buck ran probably 1/2 mile and layed down, needing a finishing shot.

Looking at my buck, the wound channel was pretty small. Yes the buck dropped, yes he died. No the bullet did not fail, however, because of this I will be choosing a Ballistic Tip next time, as I feel the Accubonds are a little too tough for the light skinned Antelope.

Looking at my buddies buck, his 140gr BT entered perfectly behind the shouldertaking out one lung, severing the esophogus and exiting the neck in front of the off side shoulder. The wound channel was massive.

Now looking over the very basic details, my buck dropped and died faster than his. But this does not equal a better or worse bullet.

Hunting is an imperfect sport. Suggesting that those whom do not take your advice do not care as much about the animals they hunt is a very slippery slope, my friend. We should pass on our knowledge in the field to help others, and not get our feelings hurt if they don't take our advice.