Standard Cartridge Series - 7mm Remington Magnum

[Jay Edward (deceased)]

Like the .270 Winchester, this cartridge really needs no introduction.  It is a fine cartridge and much admired by North American big game hunters.  I still would like to point out the information shown on the .280 Remington/7mm Express thread...as you know, I feel that cartridge is a good 'balance' between the .270 Winchester and the 7mm Remington Magnum. But as a long range big game cartridge, I feel that this cartridge might be a good starting point.

[Daryl (deceased)]

:)
 
One of my favorites!  My load for the 145 gr Speer BTSP and Grand Slams is the same as that listed for the 140 gr bullet.  I've taken elk, mule deer, whitetails, antelope, bear, and even coyotes and a few p-dogs with mine.
 
I've been using that rifle since about 1987 so I know it's capabilities and limitations well, but when it booms, some unfortunate critter generally falls down without getting back up.  It's as ugly as sin with it's matte blued finish and black synthetic stock (Browning A-bolt), but it's great for a rifle that's used hard in rough, rocky, thorny country.  It's not the biggest I've used, nor the smallest, but it works!
 
Daryl

[gitano]

I've got a soft place in my heart (or head) for this cartridge as I have taken a great deal of game with it. As usual, I chose not to follow the crowd wrt bullet selection. While I have used every bullet made from all of the "big" NA bullet manufacturers, I have settled on, and ONLY use, Speer's 115 grain HP because I can shoot three-shot clover leafs all day long with that bullet. My load is very similar to that listed above, and I get essentially the same values for velocity. I've taken critters sized form Alaskan bull moose to jackrabbits with it, and they've never moved more than a body length.
 
After assembling a 7mmx300 Weatherby, I put the Model 700 7mm Rem Mag down. After the 7x300 using a 175 grain Nosler Partition caused me to have to chase a coastal brown bear into the alders at 10 PM, AND having to shoot it three time to kill it, I bought a .338 and put the 7x300 down. I've picked up neither the 7mm Rem Mag or 7x300 since getting the .338. As it turns out, and as it will be seen when Jay posts the info on the .338 Win Mag, the 7mm Mag is just the .338 Win Mag necked down to .284". A 175 grain .338 bullet "hits harder" than a 175 grain .284 bullet - and a 225 grain .338 hits WAY harder than a 175 grain .284.
 
Maybe "hitting harder" than a 7mm mag isn't necessary. If not, then a 7mm mag is not likely necessary over the .280 or even 7x57. Of course, if you are inclined to shoot at ranges greater than 300 yards, then the 7mm Mag and it's bretheren are probably more to your liking than the .280 or 7x57.
 
The 7mm Rem Mag remains one of my all-time favorite cartridges.
 
Paul

[Hunterbug]

I shot my first buck with my Grandfathers 7mm Mag. I personally have never owned one as I feel that it's too close to my 30-06 in performance. But he has used his for deer, elk, and antelope and it works great.

[CAfrica]

Gitano,
 
A 175 grain .338 bullet "hits harder" than a 175 grain .284 bullet - and a 225 grain .338 hits WAY harder than a 175 grain .284.

I agree with your statement regarding the heavier bullet.  As a matter of fact, in 338 I would probably go for a 250gr if distance was not an issue.
 
I would like you to expand on your opinion with regard to the 175 grs.  The 338 would make a bigger wound channel.  The 7mm with its bettter SD & BC would be a better long distance load and have better penetration capability. Unless the 338 is launched at a higher velocity, and retains that velocity advantage to taget, I don't see how it hits "harder" than the 7mm.
 
C

[gitano]

My comment regarding the 175 grain bullets was predicated on the premise that impact velocities were the same. It is not unreasonable to assume that this condition is a "given" because ANY other condition renders the comparison invalid. However, I will calculate that set of ranges over which it could reasonably be expected that a 175 grain 7mm Remington Mag bullet and a 175 grain .338 Winchester Mag bullet might have the same velocities.
 
Thie "initial conditions" if you will, are:
 
1) The only 175 grain .338 bullet that I am aware of commercially is the Barnes "X".
2) Of the people I know with 7mm RMs, not a single one, including myself, now handload 175 grain bullets, (however it's probably a popular loading in Africa, even up to 195 grains), therefore, I am going to use published muzzle velocity data for a factory 175 grain load. Based on my personal reloading experience, I don't believe the bullet actually leaves the muzzle at anywhere near 2860 f/s (780 m/s), but I'll use the value anyway just to make the best case for the 7mm.
3) I've NEVER seen anything but a RN on a factory 175 grain 7mm bullet, so that's the BC I will use - .285.
4) I will use the muzzle velocity from my .338 handloads, 3194 f/s (973 m/s), because nobody loads 175 grain Barnes' in factory cartridges to my knowledge.
5) Since the 175 .338 is now out of production, and I can't quickly find the BC value from my records, I'll use the BC for the 165 grain "X" - .337. the BC for the 185 .338 is .437, and the 175 is more than half way between 165 and 185 grains, but I'll continue with the scenario that favors the 7mm.
 
First and foremost, there's no need for further evaluation, as both your premises:

The 7mm with its bettter SD & BC would be a better long distance load and have better penetration capability.

are not consistent with the above "initial conditions". However, continuing the effort to favor the 7mm, let's assume a handloaded 7mm bullet.
 
Hornady's 175 has a published BC of .462. Since we're "going" here, I'll extrapolate the .338 175's BC at .387 (still likely an underestimate). Furthermore, the average DO NOT EXCEED load for the 7mm RM 175 in Nosler's most recent manual (Nosler "likes" the 175 grain bullet in the 7mm RM more than Hornady does, therefore further favoring the 7mm as much as possible) is 2834 f/s (~864 m/s).
 
7mm Remington Magnum Handloaded 175 grain bullet, MV 2834 f/s, BC .462.
Velocity in 50 yard increments out to 500 yards, a point 200 yards beyond which I would ever shoot. Still, the 7mm never "catches" the .338 in velocity, and therefore does not "catch" it in delivered energy or momentum. For completeness, here are the numbers:
 
velocity (f/s)......KE (ft-lbs/sec^2)...............Momentum (ft-lbs/s)
2834.........................3120..............................2.202
2729.........................2894..............................2.121
2627.........................2680..............................2.041
2527.........................2480..............................1.963
2429.........................2292..............................1.887
2334.........................2116..............................1.813
2241.........................1951..............................1.741
2151.........................1798..............................1.671
2064.........................1654..............................1.603
1979.........................1521..............................1.538
1897.........................1398..............................1.474
 
Here are the .338 numbers.
 
3194.........................3958...............................2.480
3058.........................3633...............................2.376
2927.........................3330...............................2.275
2800.........................3046...............................2.176
2676.........................2782...............................2.079
2556.........................2537...............................1.986
2438.........................2310...............................1.895
2325.........................2100...............................1.806
2215.........................1906...............................1.721
2108.........................1727...............................1.638
2006.........................1563...............................1.559
 
Turns out, the actual BC for the Barnes 175 grain .338 "X" is .392. So the numbers improve for the .338 even more.
 
A comment on sectional density. Sectional density was a characteristic used to determine ballistic coefficient before the "modern era" where ballistic coefficient could be directly measured. It was useful in ESTIMATING BALLISTIC COEFFICIENT when most bullets were of the basic roundnose, or "G1" design. It was NEVER intended for estimating penetration. For those bullet shapes, AND THOSE ALONE, it is an acceptable but cumbersome, predictor of penetration in general. HOWEVER, today, ballistic coefficients are directly measureable even by a layman (albeit a well-heeld one.) Furthermore, the myraid bullet designs available today render the use of "sectional density" practically absurd as a predictor of penetration. Momentum, equal to the mass times the velocity, is both easy to calculate and a far more "correct" and precise ESTIMATOR of penetration. The single "arena" where it might still be reasonable to consider SD when trying to estimate penetration could very well be Africa, where roundnosed "slugs" are apparently still in wide-spread use. It's STILL not as appropriate or as accurate an estimator as momentum.
 
The current misuse of the term sectional density is among the many reasons for my disdain of most "gun writers" in general. Most people are excused from ridicule for using SD so prolifically, by virtue of being repeatedly mislead by self-proclaimed ballistics "experts" AKA "gun writers". Sadly, the term is now so entrenched in "ballistics" vernacular, that it seems extremely unlikely that it will ever be extracted. That is both the burden of the hunting community, and the shame of truly stupid "gun writers".
 
Rant off, and an to the .338/7mm evaluation.
 
This whole excercise clouds the real foundation stone upon which I made my initial comment regarding "hit harder". Namely, considering two or more bullets of similar weight (rendering KE moot) and impact velocity (rendering BC and KE moot), the larger diameter bullet is going to "hit harder". I have come to this conclusion IN SPITE of starting my ballistics "career" absolutely believing that KE was "king". While I am unaware of ANY true method for quantifying the contribution of diameter on delivered energy, I do have both a plausible (to me) explanation for the observed phenomenon, as well as a way to measure (as oposed to estimate or predict) it. I will disuss that in a separate thread.
 
Finally, in classical quantitative analyses, it is often valuable to take things to "extremes" to clearly illustrate a concept that is confounded by "noise" in a system comparing parameters that are "close". Such is the case with MOST "my-bullet/gun/cartridge-is-best" arguments.
 
Let's take a .284 bullet that is 24" long. I'm not going to estimate it's weight, but let's just say for discussion's sake that it's a pound, 7,000 grains. Let's say we can get that "bullet" going 2100 feet per second (~641 meters per second). An absurd figure in a handheld firearm, but "handheld" is irrelevant wrt to this illustration. The calculated KE for such a bullet at the muzzle is 19,581 ft-lbs/sec^2. Does anyone here really believe that pencil is actually going to "hit harder" ANY harder, let alone more than 2x as "hard" as a 500 Nitro Express shooting a bullet that is going the same 2100 ft/s but weighs 1/10th the mass (700 grains)? I certainly do not. The PRINCIPLE applies to ALL diameters. How IMPORTANT it is when diamters are separated by small amounts like say .277" and .284", or .257 and .264" seems "a tempest in a teapot" to me. However, depending on HOW and over what interval of time the bullets of similar diameters drop their respective energies, the effect on the animal ("hit harder") can be quit different.
 

Paul

[CAfrica]

OK Gitano, very informative (and obviously the 338 outperforms the 7mm) but, the essence of your point is, two same weight projectiles at same velocity, the one with the larger diameter "hits harder".
 
To take your example of extremes and comparisons (the pencil to bullet comparison), which would you believe hits "harder" (same velocity), a 30 calibre 180gr bullet or a 45 calibre 180gr bullet?  In this instance, we are at the ridiculous at the other end.  The 45 calibre would be a VERY short handgun bullet. Even assuming it doesn't "fail" at impact, it is unlikely to have very good penetrating capability (i.e. I doubt it would break a large shoulder).
 
Even though both bullets have the same momentum, the larger diameter bullet has to overcome a lot more resistance in plowing the wound channel and I would predict that it would be a poor penetrator in any tough medium.
 
MY OPINION:
 
Assuming both bullets retain 100% weight and both expand to 150% of initial diameter, the larger diameter bullet would "hit harder" as long as it retains a reasonable SD (I agree with what you said ragarding SD, but in this instance it is appropriate to use it as we are referring to extremes of length (and therefore SD).
 
If we remove the assumption of 100% weight retention, then I would postulate that the smaller diameter bullet would MOST LIKELY retain more weight and again the "short fat" bullet would reach a point where it retains insufficient weight to penetrate sufficiently for effective hunting. At this point once again my opinion would favour the smaller diameter bullet.
 
Since these points where the situation is reversed would invariably be on the extremes, I would support the your viewpoint except in instances where PENETRATION is of the essence (thick skinned tough animals, I.e. the 175gr 7mm has been used to hunt elephant (solids for brain shots), I wouldn't try it with a 175gr 338).
 
Regards
 
C

[gitano]

CAfrica,

I am enjoying the opportunity to discuss this topic, and I hope you are too.

WRT your example of 180 grain .30 and .45 caliber bullets, I can share some personal experience with .44 caliber (.430" actual diameter) 185 grian HP bullets on big game.

As I am sure you have, I have read that HP bullets for big game were "bad juju", prone to "fragmentation" or "blowing up" on the skin. For the most part I accepted this gunwriter/guide/PH "mantra". First, they are "experts" so they oughtta know, and second, HPs were after all, "designed" to "explode". However, I was also young and in a stage I refer to as my "speed (aka KE) uber alles" time. I had a Ruger Redhawk in .44 Mag with a 7.5" bbl. The purpose for which I purchased the revolver was personal protection while in the woods. (The reasons for this choice of firearm are discussed elsewhere.) As has been the case in so much of my personal hunting and shooting "education", enlightenment came in spite of myself and in circumstances that were not what the "experts" even considered.

As a result of crunching numbers and personal experience with bears and guns, I decided that I didn't really care if the bullet "exploded" on impact. I wanted the most KE possible dropped in the bear. (I've since changed that opinon, but that is the opinion that got me to a certain "place", that lead to a certain "enlightenment".) The .44 mag revolver bullet that delivered the most energy to a target within 50 yards was the 185 grain HP handloaded to about 1850 f/s at the muzzle. I was relying on the HP to keep the bullet in the bear and drop ALL its energy IN the bear.

In order to keep this post at least a little bit shorter, I'll skip the "bear tale" and cut directly to the shot. I shot a large coastal brown bear at 62 paces with the above revolver-bullet combination. The bullet struck the bear in the center of the left "collar-bone", trashed the left lung and surrounding tissues including badly bruising the top of the heart, and exited out on the right side of the spine breaking the last rib as it did. In all, that HP, leaving the muzzle at about 1850 f/s traveled through about 3 feet/1 meter of bear, breaking a bone both entering and exiting.

If this was the only instance I had with that revolver-bullet combination, I would not be so confident that this performance could be expected in most circumstances. However, encouraged by that initial experience, I took the Redhawk as the primary weapon while hunting several other species of Alaskan big game. With it I have shot dall sheep, black bear, moose, blacktail deer and caribou. No shot on any of those animals has been greater than 47 paces, and discounting coup de grace, the shortest was 11 paces on a dall sheep. I cannot remember a case where the bullet did not break at least one bone.

I have never recovered a bullet.

Now, all that said, let me acknowledge that we are not talking about a .45 caliber bullet with an impact velocity equal to a 185 grain .30 caliber rifle bullet. I suppose, that at some impact velocity, the HP will have to come apart. However, there are a few points I would like to emphasize.

First an foremost, most "experts", whether they be "gun writers", guides, professional hunters, or the like, rarely are truly experts. In fact, in my opinon, if an "expert" says it's true, there's a very high probability that it is absolutely false in most circustances.

Second, so-called "designed performance" is about 99% marketing hype, 0.9% engineering "expectation" and about 0.1% emperically determined.

Just about every (but NOT EVERY) bullet made today is fully capable of performing admirably in the game fields. Another specific example is Sierra's Game King line of bullets that is derived directly from public pressure based on the performance of their Match King (HP) bullets on big game animals.

I have seen too many times to ignore, the diminutive 25 grain HP in .17 caliber doing 4112 at the muzzle, simply pulverize the bones of big game animals - on occasion after penetrating several inches of muscle, and never at a range greater than 159 lasered yards.

Finally, this post is neither endorsement or encouragement for use of HPs on big game. Rather, it is the recounting of repeated personal experience that flies directly in the face of "expert tesitimony". Those reading it may take it as they wish. I have no "problems" until they start telling me either; I can't use the bullets of my choice, or sadly far more common these days, I'm unethical if I use HPs, or small calibers, or small caliber HPs on big game. Fur tends to fly at that suggestion.

I might very well agree with you WRT your last comment regarding the 175 in 7mm or .338 when deep penetration on thick-skinned game is mandatory, like an elephant skull I suppose. However, I'd probably personally choose the .338 if I could find a dense, say tungsten carbide-cored, 175 grain .338. The truth is though, if I were going to have to shoot an elephant with a .338, it wouldn't be a 175 grain bullet I'd be wanting to use.:)

Paul

[CAfrica]

Gitano,
 
I own a 357 Magnum carbine and at the velocities achieved in this rifle (1680ft/s for a 158gr bullet), I have had the experience that all bullets exited.  I have tested penetration on test mediums and were astounded that this "short" bullet penetrates the way it does.  I have used both the flat point and the hollow point and both perform exellently.
 
With regard to your comment on "gun writers", I agree in most instances.  We are fortunate that locally we have a number of people who were hunters first and became gun writers second (and I mean BIG hunters, they participated professionally in culls of large dangerous game and acted as PH's on their own concessions etc).  I have to concede that I find them fairly reliable.  The one area in which I have doubted their veracity is is the case of bullet failures.  This was until I had a 220gr 30-06 bullet (2400ft/s) "fail" on an impala rib (the bullet broke up, creating a huge entrance hole and I found two small exit holes on the far side).
 
Maybe this was just an exception, but I have stopped using "conventional" bullets in my hunting rifles (except for the 357).
 
For the purposes of this subject, I concede that a larger diameter bullet hits "harder" than a smaller calibre bullet (as a matter of fact I never doubted it, just wanted some interesting debate).
 
Regards
 
C