I have been using Federal Premium Vital-Shok with Barnes Triple Shock X-Bullet for elk hunting, but my supply of 7 mm Remington Magnum cartridges is running low. Since Barnes Bullets was bought by the same company that owns Remington, the Federal Vital-Shok bullet has changed from the 160 grain Barnes’ bullet to 140 or 150 grain Trophy Copper Bullets.
I like the copper bullets because they shoot well in my Thompson Center Pro Hunter, they have demonstrated they penetrate deeply, expand well and they don’t fragment so I don’t worry about lead in the meat.
There are many options for copper bullets if you load your own ammo. I do some reloading with Lee Loader kits, (read post on Lee Loader) but for now, I prefer to stick with factory ammo for elk hunting.
Now there are a few more options available for buying copper ammunition than a few years ago. But how do we decide which ammo to use without buying and shooting four or five different boxes? This is especially painful when copper bullet ammo costs almost $50 per box.
It seems logical to compare the ballistics for several different cartridges and choose a compromise between the flattest shooting and hardest hitting brands. Then buy a box or two of that particular ammo and test it to make sure it shoots well in my rifle. In my DIY Elk Hunting Guide, I joke about buying two boxes of ammo and shooting 39 times to get sighted in and to practice and save one bullet for the elk hunt.
The Problem with Comparing Ballistics
I would like to choose a new cartridge that performs at least as well as the Federal Premium Vital-Shok ammo (Barnes Triple Shock), but there are problems using ballistics to measure that performance. For example, the ballistics coefficient (BC) originally published by Federal was 0.508. But Barnes Bullets told me via email (Dec., 2014) that Federal calculated that BC at 100 yards and Barnes calculated a BC of 0.443 at 300 yards for better long range results. BC in this post always refers to G1.
I’m sure most of you know that BCs are not constant values, but change with velocity (which changes with distance). The simplest explanation of BC is the estimated fraction of 1,000 yards that a projectile loses about 50% of the initial kinetic energy. So, a bullet with BC = 0.508 will lose about half of the kinetic energy at 508 yards and a bullet with BC = 0.443 will lose about half of the kinetic energy at 443 yards.
Using the lower BC provided by Barnes Bullets in a ballistics calculator predicts the bullet will drop more, drift more in the wind and have less energy. Table one shows over 360 ft-lbs less energy at 300 yards than Federal used originally predicted. At 400 yards, the bullet has less than 1,000 ft-lbs of energy (based on BC calculated at 300 yards) than originally predicted.
Table 1. Comparative Ballistics with Corrected BC*
|Bullet||Wt. (grains)||BC||BC Calc. (yards)||MV (fps)||Add. Drop (in.)||Energy (fpe)||Wind Drift (in.)|
*Federal Premium Vital-Shok 7 mm Remington Magnum Ammunition with published BCa and Barnes Bullets corrected BCb, 200 yard zero, Target at 300 yards, Temp 40°F, 8,000 feet elevation, 10 m.p.h. crosswind
Are Ballistics Coefficients Exaggerated?
There have been several publications by Michael Courtney, PhD (and others), that criticize ammunition manufacturers for inflating BC coefficients:
Dr. Courtney et al. said “bullet manufacturers exaggerate BC specifications for marketing purposes because BC is perceived to be important by customers, and because many manufactures rely on overly optimistic theoretical predictions that ignore the effects of the engraving of rifling, manufacturing defects, imperfect alignment of bullet axis and velocity vector, and other factors.”
Accurate BC estimates are important because as we can see from Table 1, any exaggeration of BC will cause errors in predictions of bullet drop, wind drift and impact energy.
Dr. Courtney’s 2007 paper The Truth about Ballistics Coefficients indicated some companies overestimate published BCs by as much as 25%. He didn’t compare Barnes’ 7 mm ammo, but did test .224 and .308 calibers and concluded BCs were overestimated by 17.3% and 22.6% respectively. If true, this is not useful and is not acceptable.
His 2012 paper Comparing Advertised Ballistic Coefficients with Independent Measurements indicates that the BCs of some bullets (especially hunting bullets) were still slightly overestimated between 1% – 6.3%. The exaggeration of BCs of Barnes Bullets averaged just under 2%. Since Courtney claims the average measurement error for BC can as high as 1.5%, I can live with a 2% error.
Note: I was hoping to find the BCs for the same bullets (especially Barnes Bullets) in both publications, to see how the BCs had changed, but only found one bullet (Hornady, 0.244, 40 grain, VMAX) listed in both publications.
Back to Search for New Elk Cartridge
In addition to Federal Ammunition and Barnes Bullets, other companies (Remington, Nosler and Hornady) also load copper ammunition, shown in Table 2, which is sorted by total ft-lbs of energy at 300 yards.
Table 2. Comparative Ballistics of Copper Bullets for 7 mm Remington Magnum Ammunition*
|Brand||Bullet||Wt. (grains)||BC||BC Calc. (yards)||MV (fps)||Add. Drop (in.)||Energy (fpe)||Wind Drift (in.)|
|Federal Premium Vital-Shok||Trophy Copper||150||0.498||100?||3,025||6.0||2,239||4.3|
|Barnes Vor-TX||TTSX Boat-tail||150||0.450||300||3,060||6.0||2,217||4.6|
|Nosler & Winchester||E-Tip||150||0.498||???||3,000||6.1||2,200||4.3|
|Barnes Vor-TX||TSX Boat-tail||160||0.443||300||2,950||6.5||2,175||5.0|
|Hornady||GMX Full Boar||139||0.486||???||3,100||5.8||2,168||4.2|
|Federal Premium Vital-Shok (N.A.)||Barnes X-Bulleta||160||0.443b||300||2,940||6.6||2,160||5.0|
|Barnes Vor-TX||TTSX Boat-tail||140||0.412||300||3,100||8.9||2,060||5.0|
|Remington||Lapua Naturalis Copper||160||0.280||???||2,950||7.5||1,751||8.3|
*200 yard zero, Target at 300 yards, Temp 40°F, 8,000 feet elevation, 10 m.p.h. crosswind
aNote: Federal Vital-Shok Ammo is no longer available with the Barnes X-bullet. bBarnes Bullets calculated the BC (0.443) at 300 yards.
The heaviest copper bullet available in 7 mm Rem. Mag. has been 160 grains. That is lighter than many lead, jacketed and bonded bullets because the weight retention of copper bullets is nearly 100%.
Barnes Vor-TX Performance
If I use the 160 grain bullet/cartridge combination now available from Barnes, I will have the same basic ammo I have been using. Compare the Barnes Vor-TX 160 grain TSX boat-tail to the 160 grain Federal cartridge (high-lighted row) in Table 2. Also, if I stick with Barnes ammunition, I know the basis for the BC calculations are the same (300 yards) and therefore can be more accurately compared.
The 150 grain Copper bullets appear to be more common and the Barnes Vor-TX 150 grain bullet (tippet boat-tail) has a higher BC and muzzle velocity than the Vor-TX 160 grain bullet (boat-tail; not tipped) and is predicted to deliver more energy than the original 160 grain bullet I have previously used. These bullets require about 2,000 fps velocity for good expansion and that speed holds up out to about 600 yards. Since the Vor-TX 140 grain bullet (tippet boat-tail) has less energy than the 150 and 160 grain bullets, it will not be considered. Nor will the Remington Lapua Naturalis Copper bullet (last in Table 2), because elk hunting is no place for a round nosed bullet.
Remington Copper Bullet No Longer Available
The Remington 140 grain Copper bullet was predicted to have the most energy at 300 yards, but I don’t know the distance used to calculate the BC The muzzle velocity (MV) of that round was very fast, but I doubt the BC is really that good. It doesn’t matter since the Remington 140 grain Copper ammo is no longer available. Since the Freedom Group, which also owns Remington, bought Barnes Bullets (2009), I hope there will soon be more Remington 7 mm Rem. Mag. ammunition available that use Barnes’ bullets.
Federal Vital-Shok Trophy Copper Performance
The Federal Vital-Shok 150 grain Trophy Copper comes in second place in Table 2 with 2,239 ft-lbs of energy. Until told otherwise, I assume Federal calculated the BC for this cartridge at 100 yards just as they did with the original Barnes X-Bullet, which overestimated the BC by about 15%. If so, then the BC of this bullet would be about 0.434. But even if the BC were the same as the Vor-TX 150 grain bullet (0.450) in Table 2, the energy would still be less because muzzle velocity is less.
Hornady GMX Full Boar and Nosler E-Tip Ammunition
The Hornady GMX Full Boar Copper bullet is only available in 7 mm Rem. Mag. at 139 grains. I need to know more about how the BC was calculated, but I would be interested in a Hornady cartridge if they made 150 grain bullet.
The Nosler E-Tip has gotten rave reviews for penetration and expansion, but the bullet needs to hit the target at 2,600 fps or more for good expansion (See photo at Nosler’s site). According to my ballistics calculator, the Nosler E-tip will slow to 2,600 fps just short of 300 yards (Nosler & Winchester ammunition). I wish they included a photo of expansion at 2,200 fps, which would be out past 550 yards. As with the other manufacturers, I need to know more about how the BC was calculated, but if the BC holds up, it will be a cartridge I would consider, but with the knowledge that shots should be limited to 300 or 400 yards even at high altitudes.
I still have a couple of boxes of the original Federal Vital-Shok with the Barnes X-Bullet. That should be enough to make sure my rifle is sighted in and allow for more than a few practice shots in realistic hunting conditions (read post on realistic target practice). If I shoot well, I will have enough ammo for the 2016 elk rifle season. If I don’t shoot well, I will run out of ammo and have to choose a new elk cartridge, re-sight the rifle with the new ammo and make time for more realistic shooting practice before the elk season.
As of now, I will probably choose the Barnes Vor-TX 150 grain bullet. If I get more information about the BCs used by Federal, I will also consider that ammunition as well. I will also update Table 2 if and when I get more information.
Check out My DIY Elk Hunting Guide