Powder Selection

Why change bullets? If you're getting good results with the 139sst, what does changing to the 150eldx do for you?

139 G1 = .486
150 G1 = .574

For the sake of conversation, I ran the ballistics for each bullet using JBM Ballistics. Using 300fps for the 139 and 2850 for the 150. Using this data, the 139 is flatter out to 1000 yards and the 150 is about 9% better in the wind.

Add to this, that the maximum effective range of both combinations is ~750 yards on deer, leads me back to my original question...why change bullets?

As an example, I built a 300RUM and shot 208Amax in it. MANY people wondered why I wasn't shooting the 215 or 230 berger hybrids. The answer was simple, run the ballistics and you will find the 208 has better ballistics out to ~1200 yards before the superior BC of the other bullets take over. Given that I wouldn't shoot at deer size game past 1000yards, there's little reason for shooting the bigger bullets.

https://www.longrangehunting.com/threads/my-300rum-by-mcr.70809/

I use Varget in my 7-08 rifle and H414 in my pistol setup.

Not to offend, but you don't really say why you are upping the bullet weight. As mentioned in an earlier post, 7-08 does well with a 140 gr. +/- bullet in a variety of hunting applications (IMHO).

If you assume 2,850 fps (as suggested by AZshooter with RL-16), shooting an ELDx 150gr would result in an SG of 1.05 at sea level with 1:11 twist. If your twist is 1:10, the SG goes to 1.27. If it's 1:9.5, the SG is 1.41.

I subscribe to the camp that you want an SG of 1.5 at sea level to reliably stabilize, but others may differ. If you took that same 1:9.5 twist rifle up to 2,500' elevation (and you truly got your 2,850 fps), your SG would go to 1.52.

jebel said:

If you assume 2,850 fps (as suggested by AZshooter with RL-16), shooting an ELDx 150gr would result in an SG of 1.05 at sea level with 1:11 twist. If your twist is 1:10, the SG goes to 1.27. If it's 1:9.5, the SG is 1.41.

I subscribe to the camp that you want an SG of 1.5 at sea level to reliably stabilize, but others may differ. If you took that same 1:9.5 twist rifle up to 2,500' elevation (and you truly got your 2,850 fps), your SG would go to 1.52.

Click to expand...

From our testing for terminal performance a 1.5sg is the target for good terminal performance. When it comes to terminal performance it is more about the rpm's than the sg. The higher the rpm's the better a bullet will perform on impact. After all of our testing I no longer use elevation when calculating bullet stability for hunting applications. Elevation helps for external ballistics but not for terminal performance. After impact testing in media more bullets than I can remember and being involved in over 100 game animals taken and seeing results from varying bullets and stability factors, I consider 2.0sg to be ideal for hunting and 1.5sg to be the lowest to expect reliable bullet performance. Again I calculate for hunting at sea level.

If target shooting, enough stability to fly well is all that is needed. Depending on the bullet a 1.2sg can produce great accuracy.

Steve

Wow guys thanks for the awesome response. I checked my barrel and found that it is a 1 in 9 twist so calculating everything through Bergers site I am at a 1.52 sg. I decedid to go up in weight in hopes of having a little more power at longer range. Is that not gained here?

Not sure what distances you've got in mind. If by more power, you mean more ft.lbs. of energy on target, then you may be right, but I doubt it's much different (haven't run the numbers). Both bullets will make a very satisfactory entry wound of 7mm and exit wound of xx".

If, however, you mean that exploring a new round and continuing to tinker with a load will be a lot of fun? I agree. Enjoy.

Personally, I've been tinkering with the 131 grain Hammer Hunter bullet for my 7mm-08 and I've been pleased. It's all about the journey...

timmymic said:

Wow guys thanks for the awesome response. I checked my barrel and found that it is a 1 in 9 twist so calculating everything through Bergers site I am at a 1.52 sg. I decedid to go up in weight in hopes of having a little more power at longer range. Is that not gained here?

Click to expand...

Given your range of 400 yards, there is little gained by switching from the 139 to the 150. Using the same formula as before (139 @ 3000 and 150 @ 2850), the 139 gives up 90lbs of energy at 400 yards compared to the 150 (1567 vs 1656). Looking further down range, using 900lb ft of energy as a benchmark to effectively kill deer, the 150 only extends the lethal range of the 150 over the 139 by 100 yards (800 yards vs. 700).

So if what you want is superior exterior ballistics (drop and drift) and comparable terminal ballistics (energy on target), stick with the 139.

Similar to you, I have a 280Rem that is my deer killing 'carry rifle.' It has a 22"skinny barrel and weighs just 8.5lbs unloaded but with the scope. Like you, my intended use with the rifle is to kill deer from up-close-and-personal out to 500 yards. For all the reasons I cite for you, I shoot 140grain SGKs in that rifle.

Now go build a true longrange rig, chambered in something like 300wsm with a truck axle diameter barrel that's as long as your leg and kill those deer waaaaaaaay over there!

jebel said:

Not sure what distances you've got in mind. If by more power, you mean more ft.lbs. of energy on target, then you may be right, but I doubt it's much different (haven't run the numbers). Both bullets will make a very satisfactory entry wound of 7mm and exit wound of xx".

If, however, you mean that exploring a new round and continuing to tinker with a load will be a lot of fun? I agree. Enjoy.

Personally, I've been tinkering with the 131 grain Hammer Hunter bullet for my 7mm-08 and I've been pleased. It's all about the journey...

Click to expand...

What vel are you getting with the 131's? This is a tough combo to beat out to pretty long range.

On another note...I think energy is a bit of an arbitrary number that is good for comparing cartridges. With well constructed bullets impact vel is a better comparison. The gains from the heavier/higher bc bullet usually show up in wind drift. Then at a certain range the heavy will eventually win in every category. Often this is farther out than what is an effective range. If a rifle is being set up for truly long range hunting and the shooter is willing to use impact vel below 1500fps then the high bc bullets take over. This usually will mean ranges well past 1000y.

To the op:

When I am trying to decide on a bullet I will sit down with the JBM Ballistics calculator and load the prospective bullets in with the expected vel and print out each chart so that I can lay them down sxs and compare the difference in performance from muzzle to whatever benchmark you personally have for the longest range you are willing to hunt. This may very well end up not being the bullet that you think. I tell people all the time that if the highest bc heaviest bullet with low muzzle vel, doesn't give you the overall best performance for your hunting style, it doesn't mean that you can't shoot long range rocks with the lower bc, lighter faster bullet. You can still bet sodas with your buddies on who can hit the 1500y yard rock.

Steve