7mm Remington Magnum Data

[Seismic Sam]

This is a reply to the guy from Strad's bachelor/non-bachelor party at Alary's last night who was grilling me on 7mm Rmington Mag loads. Basic premise, he was in love with the Barnes 140 grain TSX bullets due to their supposed high BC and initial velocity due to their three grooves to reduce barrel friction. He thought the high velocity would allow for a reduced bullet drop, and I tried to tell him that given a group of bullets of the same caliber, the drop level was not that significant compared to the retained energy, and in retained energy the heaviest, longest bullet would win big time. Well, I was kind of right, but even I was in for a surprise. Using the Sierra Infinity 5 ballistic software, I calculated bullet velocity, bullet drop, and retained energy in 100 yard increments, going out to 700 yards. I used the BC listed for each bullet, plus the maximum velocity shown for each bullet with any powder. The bullets are listed in the legend in each chart, so you can just read that off the images below.

To begin with, let's deal with the Barnes TSX bullet. Despite its grooves, its maximum velocity is unspectacular and its ballistic coefficient is pretty lame with a value of .412. So, you got a long solid copper bullet that SHOULD have a kick-butt BC up around .5-something, but it doesn't happen. Why? Four words: Bearing area, and parasitic drag. Yes the bullet is long, like a heavy Sierra Matchking, but it's got way more bearing area than a similar lead cored bullet. Result? More friction for the same weight. Secondly, once the bullet leaves the barrel, those grooves in the bullet greatly increase the parasitic drag. Instead of the air flowing smootly over the body of the bullet, those grooves create little air rotors along the body that increase the air friction and make it slow down faster, hence the BC of .412. So you got no superior velocity vs. other 7mm bullets, plus increased drag, according to the load data from the Barnes website.

Now, the real surprise is another Barnes bullet, which according to their website is no longer offered, and it's the Barnes 140 grain XLC HPBT bullet. This was very special design, with an undersize jacketed bullet, and a proprietary coating on it to make up the remaining diameter (so it's wasn't anything like a moly coating) so it was a few mils thick at least. The maximum velocity for this beast was a smoking 3777 FPS, which is a good 300 FPS over anything else I found. And the smooth HPBT design doesn't hurt either. At the time I thought that design and coating might be a gimmick that wasn't any better than a moly coated bullet, but I was wrong and apparently the general public thought likewise, so it got phased out. Based on the data, that's a real shame.

So - the data: Velocity: The Barnes TSX comes in slightly faster than the heavier 168 Sierra Matchking, and loses any advantage after about 300 yards. The 140 grain ballistic tip with its moly coating does 2nd best, but is still a pale shadow to the velocity of the Barnes XLC.



Bullet Drop:



The smoking velocity of the Barnes XLC makes it first, and the Barnes TSX comes in dead last. That's the parsitic drag slowing the bullet down.

Retained energy: Normally, the logest heaviest bullet wins this hands down, but the high velocity of the 140 grain XLC bullet keep it on top, which is very unusual. Apart from that, the 175 grain bullet is superior from the get-go.I can tell you between the .338 200 grain Ballistic Silvertip, the 250 grain Sierra MK, and the 300 grain Sierra MK, the difference with the 300 grain MK is HUGE at 1200 yards.

[crbutler]

Sam,

Just a couple of words on the XLC bullets.

Overly Optimistic.

Used a lot of them, and the data they gave in Barnes #1 and #2 was MUCH hotter than what they have given in the later manuals. I still have a bunch, and if someone wanted them, I would sell them cheap.

I understand what you are trying to say here, and agree, but you would be better off to forget the XLC.

At least with the .257, .308, and .224 versions, I was never able to get the velocities they claimed and almost never could get (safely) to the maximum load they listed.

The TSX versions are lower pressure/higher velocity if you hold the powder charge the same. A lot of Barnes' velocity advantage was/is willingness to push the pressures up a bit. Look at what Hornady and Nosler claim for their monometal bullets which are much more similar to what the original Barnes X was. The XLC was an attempt to alleviate the pressure issues that the X had before they decided to reduce the bearing surface.

The Tipped TSX have better BC than the plain TSX bullets. The MRX have better yet.

In any case, I use a lot of TSX and TTSX bullets. They are not match bullets, although in some rifles they perform like match bullets. They are pure and simple, a better controlled expansion hunting bullet. As they are pure copper, they don't do the core separation thing when you shoot a moose at point blank range with a magnum going faster than the design spec for impact speed for the bullet, which was John Nosler's reason for developing the partition.

If you are using a "fast" rifle for hunting, or you are needing maximum penetration, the Barnes bullets are the bee's knees. They just plain work. If you want to shoot at extreme range for paper targets, use a high BC target bullet such as the A max, SMK, or Berger, or similar.

The go home point is that BC really makes a huge difference as you get past 300. OTOH if you look at drops, a .1 difference in BC is large, and it does not make that much difference at any reasonable hunting range.

[Seismic Sam]

Thanks for the info. I got my data from the Barnes #3 manual (never bothered to buy the #4), but you obviously know what 's you're talking about because you tried to to duplicate the data and couldn't. Seeing as I don't hunt, I never bought a box of Barnes bullets. The original Sierra data for the .338 SMK's were dead nuts on, and IIRC, the Nosler data wasn't much different. And yeah, a .1 difference in BC is a fairly significant deal if you get out there a ways.

[Snowgun]

Great Info Sam!

I was the sucker who was debating with Sam the merits of the 140 gr barnes.

So, the thing was Sam, I use the Tipped TSX (TTSX), as crbutler mentioned, instead of the regular TSX. I'm curious as to how that differs from the regular TSX.

And now that I know the MRX exhists, i'm switching to that bad boy.

http://www.barnesbullets.com/products/rifle/mrx-bullet/

I'm curious how these three would compare against each other. I know that I get GREAT accuracy out of my 7mm rem with the TTSX (0.3 MOA), and i've personally seen these things blow through bones like no other.

Could you cook the info on this up for me Sam? Pretty Please?

[Seismic Sam]

Actually, got more bad news. The plain 140 grain TSX has a BC of .394, and the tipped TSX only has a BC of .412. It's on the Barnes website if you look in the right place, along with load data. The 140 grain MRX has a BC of .406. The 140 grain Nosler Ballistic silvertip has a BC of .485, and the 175 Sierra Gameking has a BC of .535, and the 180 grain Sierra Matchking has a BC of .660.


Oh, and the Sierra .338 300 grain Matchking has a BC of .768, which is better than your average 50 BMG bullet.
This is it sitting next to a .223 CASE. (!!!) The existence of THIS bullet is why I bought a top-line Remington 700 Sendero SF to begin with.

[Snowgun]

WOW

Hmmm, gonna have to check out that nosler as well

Thanks Sam!

[crbutler]

And the .50 750 A Max has a BC of 1.050 (Hornady 8th) If you want to play with the big boys, get the toys... Quit playin' with that puny .338

The 160 MRX has a BC of .439, and you should be able to get 2850 FPS as opposed to a little over 3000 with a 140. If you are after a long range hunting load the bigger bullet just makes sense. The 7 MK 180 requires a 1/7 twist, which a factory 7RM is very unlikely to have. The 150 MK has a BC of .42 the 130 .39 (depending on velocity) so the Barnes actually have better/comparable BC than a comparable weight match 7 mm bullet, assuming that the factory numbers are right. ( I've found Nosler's to be a bit optimistic, Sierra's to be pretty much dead on, Barnes are a bit iffy at times)

I will say that the MRX bullets have not been as accurate in my experience as the TTSX or TSX. They are also a lot more expensive.

Trust me, Sam, the Barnes products are worlds better for game than a Ballistic Silvertip or a Gameking, at magnum velocities. They would work fine in a 7 RM if you knew nothing would be closer than 300 yards away, but that doesn't always happen.

For target blasting with a 7RM, try the Berger VLD bullets. High BC, superior QC, and not horribly expensive. Berger's have shot better for me than SMK's in multiple rifles.

[Seismic Sam]

And the .50 750 A Max has a BC of 1.050 (Hornady 8th) If you want to play with the big boys, get the toys... Quit playin' with that puny .338

For target blasting with a 7RM, try the Berger VLD bullets. High BC, superior QC, and not horribly expensive. Berger's have shot better for me than SMK's in multiple rifles.

I said: "Oh, and the Sierra .338 300 grain Matchking has a BC of .768, which is better than your average 50 BMG bullet

The Hornady A-max is not even close to a standard 50BMG bullet (which has a BC of .650 - .750) and you know it.

And yes, Berger VLD's are very good bullets, and I have a bunch of them for my .308. Unfortunately, Berger laid a huge egg with their .338 Hybrid bullet, and had to print a retraction that their original BC's could not be duplicated, and there were symptoms of bullet slumping in the barrel with some cartridges, and I got chrono data that shows it happens with the .338 Ultramag.

[RAGGED]

And the .50 750 A Max has a BC of 1.050 (Hornady 8th) If you want to play with the big boys, get the toys... Quit playin' with that puny .338

Yeah well the SMK's are 65 cents a pop, the 50 cal Amax's are what, $2.50+ each? No thanks, and anytime you want to go for 10 shot small group @ 1000 let me know, my factory 338 will gladly run against some 50bmg's, I've seen some pretty awful groups from most of the 50 guys, weather that says more about the guys buying them or the round itself is yet to be determined, but what is clear is it’s much harder to hold match grade tolerances on those large rounds.


The real big boys run custom lathe turned bullets, GS out of South Africa have 338's that are over 1.0 BC, need a 7 twist to run them but they are out there

[mnglocker]

The next rifle on my list is that new savage in .338lap.

[Seismic Sam]

Well Snowgun, here's the bad news:

Velocity:


Bullet Drop:



Retained Energy:



Couldn't get any load data for that 180 grain round, sorry about that. Dunno if it's still around, but Barnes manual #3 shows a 195 grain 7mm bullet, but the BC is in the high .5's, with the 180 SMK BC still being .660.

[RAGGED]

7mm is where it’s at right now, granted the 338 is king for practical long range work but NRA rules forbid muzzle brakes and let me tell you a full house 338 without a brake is no joke, even at 22lbs its more than I care to take. The 7mm SAUM is really coming into its own, will be my next custom build for sure, those big SMK's and Berger’s are changing the long range game.

[Snowgun]

Sam, Why the heck does the nosler have so much muzzle velocity in your graphs? If it can be pushed that fast can't the Barnes be also?

Trust me, Sam, the Barnes products are worlds better for game than a Ballistic Silvertip or a Gameking, at magnum velocities. They would work fine in a 7 RM if you knew nothing would be closer than 300 yards away, but that doesn't always happen.

CR, can you explain what you mean by the above? I've had great luck with the TTSX the last two years in a 140 g (shooting game at 100, 200, 250, 350, 500, and 550 yrds). Would you say they would be more accurate than the silvertip? I can get 0.3 MOA with the TTSX out of my supergrade. Can the silvertip at least match that?

[Seismic Sam]

Sam, Why the heck does the nosler have so much muzzle velocity in your graphs? If it can be pushed that fast can't the Barnes be also?

CR, can you explain what you mean by the above? I've had great luck with the TTSX the last two years in a 140 g (shooting game at 100, 200, 250, 350, 500, and 550 yrds). Would you say they would be more accurate than the silvertip? I can get 0.3 MOA with the TTSX out of my supergrade. Can the silvertip at least match that?

Sorry, but got no clue on the velocity. Based on crbutler's experience, maybe Barnes got dinged in court for false advertising on the XLC and had to pull back a bit. In my experience Nosler data has always been right on. Don't forget that the TTSX bullet is all copper, which means longer bearing surface for the same weight, and it isn't moly coated either.

And accuracy and BC have NOTHING to do with each other. The TTSX could very well be a perfectly accurate bullet, BUT a bullet with a .4 BC just can't compete with a bullet with a .6 BC at longer ranges, and that parasitic drag issue is something you can't get away from. The TSX design is fundamentally flawed from an aerodynamic standpoint. Thta's why its BC is so low.

[JJ]

Trust me, Sam, the Barnes products are worlds better for game than a Ballistic Silvertip or a Gameking, at magnum velocities. They would work fine in a 7 RM if you knew nothing would be closer than 300 yards away, but that doesn't always happen.

CR, can you explain what you mean by the above? I've had great luck with the TTSX the last two years in a 140 g (shooting game at 100, 200, 250, 350, 500, and 550 yrds). Would you say they would be more accurate than the silvertip? I can get 0.3 MOA with the TTSX out of my supergrade. Can the silvertip at least match that?

I would guess it has to do with the fact that the TSX line is know to thru and thru at closer ranges. The Noslers and Gamekings do a much better job at dumping their energy quickly.