I tried to compare near identical sectional densities of bullets across 6.5mm, .277 and 7mm. For near same S.D., the B.C.'s vary by a much greater percentage?!?

SO, both the .264 shooting 130gr bullet (sd=.266) vs .277 shooting a 140 gr bullet (sd=.261). Total difference in SD is only about 2% higher for the .264 YET, the .264 has about a 22% HIGHER B.C than the .277!! 0.552 vs 0.452!

The same can be said of the .284 vs the .277. Looks like the "270 anythings" are worst performers between the two. Why? I'm confused.


6.5 MM
130 gr Match Grade VLD Hunting 0.552
140 gr Match Grade VLD Hunting 0.612

270 Caliber
130 gr Match Grade VLD Hunting 0.452
140 gr Match Grade VLD Hunting 0.487
150 gr Match Grade VLD Hunting 0.531

7 MM
140 gr Match Grade VLD Hunting 0.510
168 gr Match Grade VLD Hunting 0.617

Revealing, isn't it?

bullet companies could make a higher BC .277 bullet. for whatever reason they just don't. .257 suffers the same fate.

If one compares apples and oranges the difference might be ostriches.

SD comparisons are valid when all else is equal. .277 does not equal .284.

So, if I'm reading this right, the .277 bullets have a lower BC, which means they create more turbulence, which means an area of low pressure behind the bullet - a vacuum. So, then, that means .277 bullets suck.

It's all because the .270 sucks.....

Kaiser Norton

okbob51,
not an arguement, looking to learn here, what would bullet manifactures have to do to the 257 and 277 bullets to increase the BC?

Shrink them by 0.013" diameter.

I'm guessing then would have to increase twist first on factory rifles and still you would have a lot of rifles out there that wouldn't like the new bullets. Rifles that work just fine with what they have been shooting for years.

Change the shape of the bullet.

For example, if you check the TSX bullets on the Barnes site, the 130 gain .277 TSX has a slightly lower SD than the 140 grain .284, yet the .277 has the higher BC.

Make them heavier, add a pointed plastic tip, and a long boattail. I would love a 140gr 257 bullet. Load it in a necked-down 308 case and build light rifles with 8-twist barrels to shoot them in.

That was done quite some time ago and far more aggressively. Known as the Barnes QT cartridges which included a 150 gr .257 as I recall. Used a 1:5.5" twist.

I-phone short version: BC=SD/I I=form factor

For a given form BC is proportional to SD. For the same form and weight BC is inversely proportional to diameter. As I recall. I don't much care for I-phones and their BC sucks.

Agree'd

This ain't rocket science...6.5's and 7mm's started as military caridges of modest velocities loaded with very long bullets that required fast twists to stabilize them.Like many military cartridges,they were also use for target shooting, the heavy weights were retained,along with the faster twists.Obviously they were also used for hunting.

Bullets got better,velocities got higher; the fast twists were retained.

OTOH, the 270 had no military nor target history; the Winchester version was designed as a hunting cartridge with a 10 twist that adequately stabilizized the relatively short 130 gr C&C bullets originally designed for it. High velocity was its' forte.It also stabilized 150 gr spitzer bullets.These two weights proved fine for a majority of the hunting for which the cartridge was suited.

No one made very high BC bullets for the caliber because most 270's have a 10 twist, and the cartridge has no target or military history.Very long, sleek 270 caliber bullets of high BC could be made(one company is making them now),which would put it on a par with the 6.5's and 7mm's,although the slightly larger bore diameter of the 7mm's likely makes them the best of the bunch.It shoots heavier bullets...Even as it is,though,you gotta sift through a lot of gack to prove the 270 truly "sucks".

Given cases of equal capacity and bullets in the same weight range at similar velocities,,the 270 kills BG animals as well as comparable 6.5's and 7mm's.Anyone who thinks otherwise, is delusional, or has no experience shooting animals with it..


I stongly suspect the 270 is "better" than many of its' detractors.If you can't do it with a 270, you likely can't do it with a comparable 6.5 or 7mm either.

Not even a Mashburn?

dt: Why I said "comparable"

Honestly, we all know that certain 6.5 and 7mm bullets have very high BC's and obviously have an advantage.....but the bulk of them have BC's that are about the same as 270 bullets,which is why I don't understand all the comparisons sometimes.

Great comments as usual Bob. All of the gratuitous swipes at the 270 by the usual gang of 'haters' aside, there is an interesting point raised in the OP regarding bullet design. Your points about faster twists and heavier (for calibre) bullets are well taken, and as you've essentially said it is pretty obvious that the 270 isn't going to excel at something it wasn't designed to do well in the first place. However, let's try to eliminate the issue of heavier bullets for the moment. If we consider only the 140 grain bullets in each of .264, .277 and .284 from the OP, there is still an interesting phenomenon. Obviously, at the same weight, the .264 will have the highest SD, and so it comes as no surpise that, given the 'same' bullet design, it has the highest BC as well. However, the .277 has a slightly higher SD than .284 and yet the BC of the .284 is actually a bit higher. It would be interesting to hear some comments from those 'on the inside' with respect to bullet design on why that might be.

Take a 270 bullet a 6.5X55,30/06,6.5/06,280 bullet throw them in a bag,shake them up,and pull one out.Does not matter which one,they will all do the same job.Reading ballistic coefficients out of a Reloading Manual is meaningless as they change with velocity.

deadkenny: Yes...maybe they have to design them that way, so they will shoot in the slower 270 twists? I dunno...

....and I think the point is the BC's are "slightly higher"....and it seems the real advantages come from those 6.5's and 7mm's that have substantially higher BC's,bullets like the 162Amax, or the Bergers, etc.I can understand the differences with those...but not with many others.

I wonder what a 162 270 bullet would look like? But no one is gonna build it,except maybe smaller custom makers who also build custom barrels to shoot it..

I have had problems getting 130 AB's and 130 Swift 2's to shoot in the 270 Win....is this twist? I dunno.....

I just got a 9 twist Brux 270 barrel....maybe I should have bought an 8" twist?

Bob pretty much nailed it. Would be easy enough for manufactures to make VLD bullets in .277 that matched their 6.5 and 7mm counterparts' BCs, but those bullets would require a faster than standard (for .277) 10" twist.

It appears that Berger's VLDs were made with as high a BC as possible in their respective weights as a 10" twist would allow.

Same goes for the .257s also.

Wishing everybody a very Happy Thanksgiving!

John

Taking the liberty of "improving" BobinNH's statement.
Given cases of equal capacity and bullets in the same weight range at similar velocities, comparable 6.5's and 7mm's might kill BG animals as well as the 270.
Time has proven that: "I stongly suspect the 270 is "better" than many of its' detractors. If you can't do it with a 270, you likely can't do it with a comparable 6.5 or 7mm either." I could not improve this statement.
In the field, much to much can be made of some of the technicalities. As a hunting tool, the 270 has withstood the test of time. Combines with John Noslers 60 year old Partition it simply gets the job done. Not even sure the newer, high tech, bullets, exceed that standard.

fishdogs; Given all the 270's glaring deficiencies as a hunting cartridge, I don't know how it's lasted this long....

Matrix Ballistics is producing a high BC .277 VLD 165gr (BC .650). Reports have been good in higher velocity .277's such as the 270 Wby. Agree with above, I'm very content with my 270 Win's shooting 150gr NPT's and 130gr Tsx's. Also a big fan of the 7mm's and 6.5's.

There is no "magic" caliber that is inherrently better than everything else. There really is no reason for this argument to continue, except for the entertaining comments and jabs at certain people that take it sooo well. The .277" bullets are a little bigger than the .264" bullets, and the .284" bullets are a little bit bigger yet. Bullet construction and velocity make a whole lot more difference in performance than these small differences in bullet diameter. I have rifles that shoot .264" and .284" bullets, and have had the .277", though not at this time. I have a hankering to try a 270 Win with 160gr Partitions. Maybe someday. Maybe not.
Either way I will continue eating venison.

One of the biggest pluses for using high BC bullets and I'm surprised it has not been mentioned is that because of the higher BC's with comparable SD's.
You can use lighter powder charges in 08 size 26 and 28 caliber cartridges to equal 06 in 27 caliber in field performance.

High BC bullets in 08 size hulls do the work with 10 to 15 grains less powder than 06 size. Hence, less recoil.

I can take a 260 Rem with a 125 NP and equal field performance of a 270 Win 130 NP.

If you can't do it with a 260 Rem or 708 Rem, you likely can't do it with a comparable 270 Win either.

SU: True enuf! They are all very close.Which is the only point, really....

The lower BCs for the 270 were mandated by a consortium of state fish and game agencies many years ago. They found that users of the 270 were on average much better shots, better hunters and were taking much more than their fair share of game. So, in an attempt to level the playing field between 270 users and other hunters, the fish and game agencies required bullets manufacturers to make only less efficient bullets for the 270.
This handicap has not had the required effect, and now experimenting with other ways to prevent the overwhelming success of 270 users. Montana for example is considering making all 270 owners either covering their entire rifle with blue tape or wearing a cowbell around their neck.

Fred

OH MY GOD!





Happy Thanksgiving Fred....

This statement right here is precisely the reason this argument continues. A lot of people disagree with it because of the word "equal." While the performance of those two loads is very similar, and the difference may not be seen by watching the animal die, they are not equal. The velocity may be the same, but one delivers a larger, heavier bullet. Personally, I prefer the 260 load because of lighter recoil, but I do not delude myself into believing it is equal to the 270 Win load. Many, MANY people prefer the 270, and they are not making a mistake.

Same back at you, Tom!

Fred

Thank you for more clearly articulating my question.

Oh but your are so wrong on this point. You only mentioned part of my statement. I said "equal in field performance".

With only 2" of drop difference between the two at 400 yards, the 260 has more than enough speed at 400 yards to kill anything the 270 will, and with only 5 grains less bullet weight.

Only a 270 delusional nut would think he has an advantage.

And as the distance gets further the higher BC bullet of the 260 gains on the BC deficient 270.

That's so others are distracted from noticing that they're carrying a .270. It's a safety thing, if someone suddenly walks up on a hunter carrying a .270 they might start laughing uncontrollably and fall off a mountain. The blue tape and cowbell lets others know that there's a .270 owner nearby so they can tie themselves to a tree or something before the spasms hit, thus preventing unnecessary injuries and deaths.

It all depends on what the specific choice of bullet, and purpose is. A 260 Rem might 'gain' on the 270 Win out at 1000 yards, but then frankly if I actually intended to shoot something at 1000 yards neither would be my first choice. If one were wanting to use a TSX for instance, they could shoot a 130 gr TSX out of a 260 at 2800 fps at the muzzle, with a BC of .365, or they could shoot a 130 gr 270 at 3200 fps with a BC of .431 (all based on Barnes load data online). I don't see that the 260 would be doing much 'gaining' at any range under those circumstances.

That's as real a supposition as is in TWO threads.

THANKS.....Jerry

If a shooter wants to hamstring himself by using Barnes bullets that's his choice.

That's why I chose a 125 NP and 130 NP at 2,950 and 3,200.

Berger did this on purpose. They said that .270 bullets would mostly be used in hunting rifles (vs target rifles throated for the purpose) so made the bullet so it would be more likely to be closer to the lands in a factory .270 rifle to improve accuracy vs making as streamlined as possible as they did for 7mm/.264. The only other place where 7mm bullets are more streamlined in same weight is the 140 nosler btip vs 140 277 btip. The majority of makers have .277 bullets of the same weight with higher BC than 7mm as expected due to higher SD.

Lu

This is what Eric Stecker wrote on another forum:

"Since we knew the 270 cal bullet were going to be used mostly by hunters we adjusted the VLD design to be more magazine fed friendly. Also, a slightly shorter secant ogive tends to shoot well with a jump so you can take your round out of the chamber and not worry about sticking the bullet in the rifling (and getting an action full of powder in the middle of your hunt). We did everything we could to keep the hunter in mind. As time passes and interest grows for a higher BC 270 cal we can make some down the road"

Lou

I did not miss the "field performance" part of your statement, and I agree with you that field performance is practically equal for all intents and purposes. You'll get no argument from me about that. My point was that people who love and prefer the 270, who number not a few, will always claim their choice is better because of that few fps more velocity, and few grains more weight, and few thousandths more diameter. That is why they/we continue to argue the point. It's what people with preferences do. Everybody tends to defend their personal choices. The neighbor kid never ever misses a chance to tell me how his choice of broadhead is better than mine and everyone else's, even though I have outright stated to him on more than one occasion that I don't like his frickin' broadheads. I do this because the boy needs to start thinking for himself a bit instead of following the old lines of BS that typify the opinions of his misguided forbearers. But it's a losing battle because he continually chooses the false security of the old-line BS to that of real life experience and critical thought.

Berger intentionally made the 277 bullets with lower bc's because they did not want to offend those who love the 6.5 & 7 MM's. Just imagine the impact that having the 270 dominate the target world. There would only be one type of dies, fewer powders, fewer barrel makers, few bullet makers, and only one type of brass. Loading manuals would be thinner. The world would come to an end. Rifle makers would go broke etc.

Maybe Jack will chime in -

Meanwhile, off to shoot my Tiger Striped 260

Fair enough, and I did say it depended on bullet choice and particulars of the intended use etc. FWIW I ran a quick ballistic calc with default assumptions and those two bullets / muzzle velocities, and they showed the the 270 was still faster even out at 1000 yards. I'm not denying that appropriate game would be taken by either of those with decent placement. However, that still doesn't amount to 'equal' field performance, which includes factors such as drop, wind etc. You're still talking about a lighter slower bullet.

Thanks for the additional info. That's the key point, even with with same 'design', the bullet shape can be 'tweaked' for different calibres, giving differing weighting to different factors.

Have you submitted your 'design' in the other thread?

Ah, but deadkenny, what did your fancy ballistic calc say about wind-drift? I think that people here are saying that wind-drift will be MUCH higher for the 270 than for the 260.

Will it?

Windage is actually slightly higher for the .264 125 grain NP than for the .277 130 grain NP out to 1000 yards, according to the calc. The 250 fps advantage at the muzzle takes quite a bit to overcome.

While some are better no doubt, some studies indicate published BC's are exagerrated:

http://arxiv.org/ftp/arxiv/papers/0705/0705.0389.pdf

I have to wonder if they're more so in target calibers.

The threads bashing the 270 Win remind me of the haters of the good sports teams...they hate them because their team isn't as consistenly good so they bash them in an effort to make themselves feel better about their teams inadequacies...

M1Garand,

How old is that article? No doubt some of the BCs published by manufacturers are still inflated, but Berger has re-evaluated all of their published BCs over the past few years. Bryan Litz, who did BC testing for Berger, has also written a book in which he published field tested values for BCs for 236 long range bullets. My impression is that Litz's book covers the most popular target bullets (at least the long-range target bullets), so you don't have to just believe what manufacturers publish.

Based on what I've read, I would tend to trust the current BC values published by Berger. However, as I'm sure you know, BC varies some with velocity, so one value doesn't necessarily give you enough data, depending on the individual bullet.

I believe it's from '06 or '07. I think Berger did change their BCs, I don't know about the others, but I thought the results were interesting how much variation there is.

Fellows - I have a verbal agreement to buy a 6.5X55 BUT I'm telling you all this DRIVEL about their superiority is about to make me CHANGE MY MIND.

After a few knowledgable sources posted y'all left the 6.5 for hunting thread and started this one on BC. ? Wonder Why ?

Even You Ramblin Razorback said "that the 260 catches the 270 Win at 650 YARDS". Well it takes it long enough.

I intend to go thru with the purchase AND next yr. I will post some REAL hunting scenario COMPARISONS. I'm hunting now and will be prepping to move in the Spring and don't have time even to use my Pressure Trace equip.

There are TWO known facts ALREADY. The 270 generates more energy thru realistic hunting ranges. What PERCENTAGE of hunters shoot & kill game past 400-500 yds? A very few do and if they're competent, I have no problem. The VAST MAJORITY of hunters don't and don't attempt.

The 277 HAS a larger wound channel than a 264. It starts larger and with HUNTING (not target) bullets of comparable construction it expands larger. I'm NOT saying the 6.5s are inadequate at all BUT I'm convinced they are NOT superior.
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BTW I like cheese on my bergers!

C'mon jwall. Now you're just baitin' the zealots. We already know the 6.5mm bullets are superior.

I like the .270. If it weren't for that cartridge we'd have hardly no humor around here at all. It Kills me I tell ya!