Range Report 308 vs 260

[arsh1055]

Hey all.

I have done some research looking at ballistics programs etc.
My question, the .243 and .260 are flat shooting rounds out to a 1,000 yds. Flatter than .308, buck the wind better. Is there a bullet weight and type in .308 that will match the .243 & .260?
Would a 110 gr BTHP match .243 DTAC ballistics and flight ability to 1K. I know there are many different bullet weghts for .308. Do any of them share the same "flatter trajectory and wind bucking capabilities" of the .260.
I realize bullet shape,ogive, boattail all effect flight characteristics. 168 gr bullet wgt seems to be the ususal long range bullet weight for .308. ?????????

I hope this question is not to elementary.
I appreciate any knowledge gain here.
Thanks,
Rob

 

[Ryanar15]

Re: 308 vs 260

all are great rounds but i will be biuding a 260 with a 8.5 twist

 

[LoneWolfUSMC]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: arsh1055</div><div class="ubbcode-body">Is there a bullet weight and type in .308 that will match the .243 & .260?</div></div>

Not to my knowledge.

If there was, I would be on it like a fat kid on a Twinkie. Several on here are experimenting with the 208 AMAX. I am getting ready to run a workup with it too. If it plays out like the calculator says, then the wind drift is going to be awesome. The drop will be somewhat less than awesome.

The .243 and .260 in their high-BC loads will get there flatter with a bit less drift and still be able to feed from the magazine.

The 180gr JLK looks promising for the .308, but I don't have any real world info on it and I can bet it still won't perform as well as the .243 or .260.

 

[Niles Coyote]

Re: 308 vs 260

If you want flat in the 308, 155grain bullets at high speed is about as good as your going to get. To came close to matching the 260 in wind you need to be using 208's or heavier.

 

[Greg Langelius *]

Re: 308 vs 260

Guessing you're new here, so I'll be gentle.

All are good, some are better.

I prefer the .260 for reasons that relate to the longer distances, where the .260's more ideal projectiles retain their energy better; and therefore arrive earlier, with less drop and drift.

You'd need to get someone else's views on the .243, I honestly don't know diddly about it. But others here do, and it has a lot of fans among them.

Greg

 

[arsh1055]

Re: 308 vs 260

Hi Greg and evereyone. Thanks for your replies, I do need to read a book on applied ballistics. I am a realitive newcomer. Nevr mean to sound like a ignoramous when I post. Just not always posting questions in a succinct precise manner.
Am I correct when the summation of the matter, The heavier 308 maintain a better aerodynamic flight related a longer more aerodynamic bullet. The 168-175 gr having a greater length than the 155 gr and smaller grain 308 projectiles.
The 260 rem has a greater length and better aerodynamics of the projectile.
This also of course does not bring into account casing size and powders implemented in the load.

 

[Greg Langelius *]

Re: 308 vs 260

I'd suggest Brian Litz' new book on the subject. Not only is it especially good, he posts here, so direct questions and answers are at least a possibility. I'd suggest you save them for after reading all of it, most of them will be answered in the process.

Essentially, your intuition is serving you right.

Long range and long bullets go together well. The 308's additional diameter requires it to pitch heavier bullets to achieve the same length/diameter relationship, so the lighter weight bullets of the same characteristics (we concentrate on the one called Ballistic Coefficient, or BC) which the .260 shoots can therefore be accelerated to a higher muzzle velocity by the same case capacity. This is somewhat of a simplification, but for our intents right here, it's accurate enough.

Good equipment and good ammunition are pretty essential to the process; but it's easy to get wrapped around a lot of axles here, delving too deeply into the details. They are all important, but the real common denominators among better shooters are technique, experience, and an understanding of why the basic marksmanship skills are so important. I assign attention to details to the extent where experience shows me their relative importance. Each of us will eventually arrive at differing degrees of preference for each separate area of knowledge.

While it takes a relatively good arrow to bring down the game, it's at least as much about the Indian as it is about the arrow.

Most of us agree that for reasons of affordability, as well as consistent accuracy that's tailored to the individual rifle, handloading becomes another of those common denominators associated with marksmanship excellence.

So greetings Pilgrim, your Freshman journey has ended. Another begins. At least you're starting in the right place...

Greg

 

[ALMAORFE]

Re: 308 vs 260

The 155 Scenars are longer than the 175 SMK. The good 155 hand loads are approaching some factory 260 loads. This time of year I need about 10.1 mils to get to 1000 with 175 SMK and I know some guys pushing 155's needing about 2 mils less. If you want 260 ballistics get a 260, You really can't get a 308 in that arena.

 

[arsh1055]

Re: 308 vs 260

Thank you everyone for your reply.
It seems some of the same arguement in Archery. " Aluminum arrows are heavier, greater height in trajectory to target, carry more kinetic energy, thus better stopping power." Light carbon arrows,smaller diameter, flat trajectory, geater feet per second but will blow in once side of a deer and out the other.
Rob

 

[problemchild]

Re: 308 vs 260

Do the 260's burn out barrels quicker?

 

[Victor N TN]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: problemchild</div><div class="ubbcode-body">Do the 260's burn out barrels quicker? </div></div>

More powder + smaller bore = yes

But just how long a 308 will outlast a 260 is anything but a concrete answer. The main answer is YOU have to weigh ALL the pros and cons and decide on what caliber is best for the purpose you have in mind.

 

[Chiller]

Re: 308 vs 260

Sierra 155 Grain (2156) about as close as you can get..

 

[Chiller]

Re: 308 vs 260

Just to muck up the waters....6.5 cm......

 

[BOLTRIPPER]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: problemchild</div><div class="ubbcode-body">Do the 260's burn out barrels quicker? </div></div>

More powder + smaller bore = yes

But just how long a 308 will outlast a 260 is anything but a concrete answer. The main answer is YOU have to weigh ALL the pros and cons and decide on what caliber is best for the purpose you have in mind.</div></div>





the real question should be....

will a .260 accuracy drop off faster than a .308....


answer: yes

 

[problemchild]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: problemchild</div><div class="ubbcode-body">Do the 260's burn out barrels quicker? </div></div>

More powder + smaller bore = yes

But just how long a 308 will outlast a 260 is anything but a concrete answer. The main answer is YOU have to weigh ALL the pros and cons and decide on what caliber is best for the purpose you have in mind.</div></div>





the real question should be....

will a .260 accuracy drop off faster than a .308....


answer: yes </div></div>

so how many accurate rounds would a person get from each?

 

[BOLTRIPPER]

Re: 308 vs 260

depends

 

[cwshooter]

Re: 308 vs 260

the 155 scenars do a lot to close the 308 to 260 gap. i've switched and haven't looked back.
didn't even have to buy a new rifle... i think that's a good thing??? maybe not.
cw

 

[Jedi]

Re: 308 vs 260

I no longer own a 308
I ran mine hard with 155 scenars and needed 27-28 MOA @1k

My new koolaid x47 20" barrel vs 26" on 308, 26MOA @1k

X47 match rifle 28" barrel 23 MOA @ 1k

work smarter not harder

 

[aqualung]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: arsh1055</div><div class="ubbcode-body">Hey all.

I have done some research looking at ballistics programs etc.
My question, the .243 and .260 are flat shooting rounds out to a 1,000 yds. Flatter than .308, buck the wind better. Is there a bullet weight and type in .308 that will match the .243 & .260?

I appreciate any knowledge gain here.
Thanks,
Rob </div></div>

Why yes!! the 210grn Berger VLD.

Of course you have to shoot it out of a .300WinMag, with at least a 26" barrel. But it WILL match the .243 and .260. Or is that the .243 and .260 <span style="font-weight: bold">will</span> match the .300? I forget!

 

[MitchAlsup]

Re: 308 vs 260

A couple of points:

A) the 308 has a small case and ends up not having enough powder storage capacity when being compared to the .243 and .260. Thus, inorder to get a 30 caliber to the same performance level as .243 and .260 one should be looking at at least a 30-06 and mor elikely a 300 WM. These cases have the capacity to push the 220-240 gr bullets that have the BC to perform similarly.

B) 10 years ago, nobody would have though the 155s would/could unseat the venerably 175 SMK. But the 155 is basically a 175 SMK with 20 gr less lead in the nose. Just enough to hold its shape while being fired. This gives the 155s similar BC and the lighter bullets leave the barrel 150-200 fps faster (in 308) and this propells them to greater distances above transonic.

C) The drop is merely a number dialed into the scope. Its the windage that is hard to read.....

 

[turbo54]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">A couple of points:

A) the 308 has a small case and ends up not having enough powder storage capacity when being compared to the .243 and .260. Thus, inorder to get a 30 caliber to the same performance level as .243 and .260 one should be looking at at least a 30-06 and mor elikely a 300 WM. These cases have the capacity to push the 220-240 gr bullets that have the BC to perform similarly.

B) 10 years ago, nobody would have though the 155s would/could unseat the venerably 175 SMK. But the 155 is basically a 175 SMK with 20 gr less lead in the nose. Just enough to hold its shape while being fired. This gives the 155s similar BC and the lighter bullets leave the barrel 150-200 fps faster (in 308) and this propells them to greater distances above transonic.

C) The drop is merely a number dialed into the scope. Its the windage that is hard to read..... </div></div>

This...

 

[goober]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: problemchild</div><div class="ubbcode-body">Do the 260's burn out barrels quicker? </div></div>

More powder + smaller bore = yes

But just how long a 308 will outlast a 260 is anything but a concrete answer. The main answer is YOU have to weigh ALL the pros and cons and decide on what caliber is best for the purpose you have in mind.</div></div>







the real question should be....

will a .260 accuracy drop off faster than a .308....


answer: yes </div></div>

Boltripper please explain why the 260 accuracy falls of quicker than a 308 round -cheers

 

[turbo54]

Re: 308 vs 260

All other things being equal (which is of course impossible), a .260 barrel won't last as long as .308. We all know this to be true.

Why? What we've seen/experienced. I wish I understood the physics, but I don't.

 

[captrichardson]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">All other things being equal (which is of course impossible), a .260 barrel won't last as long as .308. We all know this to be true.

Why? What we've seen/experienced. I wish I understood the physics, but I don't. </div></div>

Late as usual!

Looks like the .260 vs .308 has been beat up pretty good. Per above, the articles Bryan Litz has on his website do a real good job of covering 30 cal bullet performance.

In terms of barrel life, pressure/heat is what destroys a barrel, and the throat is usually the first to go for obvious reasons.

Rough pressure comparision:
.308 with a 175 Bullet = 38,000-45,000 CPU
.260 with a 142 Bullet = 46,000-54,000 CPU
(numbers can obviously be higher or lower depending on the load)
The higher pressures the .260 produce pound the throat area harder than a .308 would.

But how big of a difference there really is, comes down to the loads being used. Plenty of .260 shooters using milder loads, 2,700-2,800 fps, who are getting good barrel life in excess of 2,000 rounds. Sheri Gallagher won Camp Perry last year with a .260 that was reported to have had close to 2,000 rounds down the barrel.
http://bulletin.accurateshooter.com/2010...p-championship/

IMHO, the barrel life of a .260 is not that big of an issue unless you are pounding rounds out of it in excess of 3,000 fps.

With Lapua .260 brass out now, I would say the .260 is going to just keep growing in popularity. Now, if we could only get someone to make a decent off the shelf the rifle in .260! I can't believe with everyone shooting it, not even Remington does!

Best of Luck,
M Richardson

 

[BobinNC]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: captrichardson</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">All other things being equal (which is of course impossible), a .260 barrel won't last as long as .308. We all know this to be true.

Why? What we've seen/experienced. I wish I understood the physics, but I don't. </div></div>

Late as usual!

Looks like the .260 vs .308 has been beat up pretty good. Per above, the articles Bryan Litz has on his website do a real good job of covering 30 cal bullet performance.

In terms of barrel life, pressure/heat is what destroys a barrel, and the throat is usually the first to go for obvious reasons.

Rough pressure comparision:
.308 with a 175 Bullet = 38,000-45,000 CPU
.260 with a 142 Bullet = 46,000-54,000 CPU
(numbers can obviously be higher or lower depending on the load)
The higher pressures the .260 produce pound the throat area harder than a .308 would.

But how big of a difference there really is, comes down to the loads being used. Plenty of .260 shooters using milder loads, 2,700-2,800 fps, who are getting good barrel life in excess of 2,000 rounds. Sheri Gallagher won Camp Perry last year with a .260 that was reported to have had close to 2,000 rounds down the barrel.
http://bulletin.accurateshooter.com/2010...p-championship/

IMHO, the barrel life of a .260 is not that big of an issue unless you are pounding rounds out of it in excess of 3,000 fps.

With Lapua .260 brass out now, I would say the .260 is going to just keep growing in popularity. Now, if we could only get someone to make a decent off the shelf the rifle in .260! I can't believe with everyone shooting it, not even Remington does!

Best of Luck,
M Richardson </div></div>

Capt,

Your theory, like many, is neat, plausible, and wrong. The max operating pressures of the .243 (60KPSI), 260 Rem (60KPSI), 7mm-08 (61KPSI), and 308 WIN (62KPSI), are all similar, max pressure wise.

There respective case capacities are also alike, varying depending on brass construction from 53 to 56 grains.

So what accounts for the differing barrel life between the .243 Win, 260 Rem, 7mm-08, and 308 Win? Expansion ratio.....

If we take these 4 rounds, place them all in a 26" barreled rifle; load them full of the powder appropriate for max velocity:

Then the 243 Win will have the lowest expansion ratio and shortest barrel life, and the 308 Win will have the highest expansion ratio, and longest barrel life.

So blasting 46-48 grains of powder, down a 24 caliber tube, is more corrosive than blasting 46-48 grains of powder down a 26 caliber tube, and so on.....

IMHO,

Bob

 

[jbailey]

Re: 308 vs 260

How about the new .30cal bullets from Berger? They have got a hybrid line coming out in something like 155gr and 185gr weight ranges which will have long ogives and boat-tails and have G1 BCs in the 0.5-ish range. And their 185 LR-BT bullet, which has a 0.55 BC. These seem like they do a good bit in improving the 308, although the cartridge is still underpowered in terms of MV.

Just throwing those out there - I'm not a .30cal guy so I don't have real world experience with these projectiles.

 

[sobrbiker883]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JamesBailey</div><div class="ubbcode-body">How about the new .30cal bullets from Berger? They have got a hybrid line coming out in something like 155gr and 185gr weight ranges which will have long ogives and boat-tails and have G1 BCs in the 0.5-ish range. And their 185 LR-BT bullet, which has a 0.55 BC. These seem like they do a good bit in improving the 308, although the cartridge is still underpowered in terms of MV.

Just throwing those out there - I'm not a .30cal guy so I don't have real world experience with these projectiles.
</div></div>

175SMK's already run a .505 G1 BC. Maybe the .55 of the 185 LR-BT will be worth it, but the 175 is such a forgiving and easy load to run from mags in bolt and gasguns that its my choice. My buddies have had great luck with the 155's, but at a cost of shorter barrel life.

My 308 is a solid standby, but is not getting grabbed to go play at a match as long as I have a 6.5CM in the safe next to it.

 

[BobinNC]

Re: 308 vs 260

Here is an interesting comparision:

.243 Win 115 DTAC G7 BC .276 @ 3000 FPS

1000 YDS Drop -7.6 MILS -26.2 MOA Drift 2.0 MILS 7.0 MOA
--------------------------------------------------------
.260 Rem 139 Lapua G7 BC .285 @ 2850 FPS

1000 YDS Drop -8.5 MILS -29.1 MOA Drift 2.1 MILS 7.2 MOA
--------------------------------------------------------
7mm-08 Rem 162 A-Max G7 BC .307 @ 2700 FPS

1000 YDS Drop -9.2 MILS -31.6 MOA Drift 2.1 MILS 7.1 MOA
--------------------------------------------------------
.308 Win 155.5 Berger FB G7 BC .237 @ 3000 FPS

1000 YDS Drop -8.5 MILS -29.3 MOA Drift 2.5 MILS 8.7 MOA
--------------------------------------------------------
And just for comparision:

.308 Win 185 Berger LRBT G7 BC .283 @ 2650 FPS

1000 Yds Drop-10.0 MILS-34.5 MOA Drift 2.4 MILS 8.1MOA
--------------------------------------------------------

Those numbers above are "real world" performance from each of those 4 calibers, from normal 26" barrels.

Looking at all 4 calibers: 243, 260, 7mm, or 30, it is hard to make a strong case of one over the others.....If barrel life is your huckleberry, then the 308 Win is your choice.

If maximum performance is your bag, then it's the .243 Win by the briefest of margins. And you'll be on your barrel makers "most favored" X-Mas card list.......

My choice is a 7mm-08. Performance closer to the .243 Win and barrel life closer to the 308 Win.

In the end, you pays your money and you makes your choice.

Bob

 

[sobrbiker883]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body"> And you'll be on your barrel makers "most favored" X-Mas card list.......
</div></div>

I like the way you put that

 

[tylerw02]

Re: 308 vs 260

As stated above, there is no free-lunch. The .260 is flatter, has less recoil, is cheaper to load for (depending on bullet), uses more expensive brass, and wears throats faster. The best way to compare two rounds is cost per round. Look at how long the brass lasts, brass cost, projectile cost, powder cost, primer cost, barrel cost, barrel life, die cost, etc. You'll find the .308 is cheaper to shoot..and the 155 Lapuas (handloaded)are going to outshine many of the other loads.

If you are a beginner, go .308 to start with, then work up (or I guess you could consider it working "down") to the .260 Rem.

Right now, I shoot mostly .308 Win. I have a 6.5-284, a .260, 6mm, and I'm in the process of downsizing to a 6.5x47 Lapua. Seems to be the best compromise for me.

 

[captrichardson]

Re: 308 vs 260

Not my theory, but an explanation given to me by someone who makes a living building and shooting rifles at a significant level!

Per my post, an AVERAGE .308 load will develop less pressure than an AVERAGE .260 load, I am not talking theoretical max limits of the cartridges, I am talking practical real world shooting. The pressure numbers I posted are an average from about 3 different reloading references, and are more than likely typical of what you will find people actually shooting. Can you exceed those numbers, sure, and that would even further destroy the barrel at a quicker rate. "Speed Kills" can also apply to barrel life!

Sorry, I am not discounting what you are saying, but I don't think that we are talking “apples to apples”. IMHO we are both correct, but in terms of 2 different applications, one being an "average shooting situation", and one being a theoretical max.

Another analogy given to me was, take a garden hose without anything on the end, then put your thumb over the end of it and decrease the size of the opening, as you decrease the size of the opening the pressure increases sending the water further. As you take a given case like a .308, and decrease the size of the opening down to 6.5mm, then you are driving up the pressure by forcing it through a smaller opening. Higher pressure, equals more wear on the barrel.

I don't have a degree in anything related to firearms, physics, or rocket science, so I am simply passing along what I have been told by individuals who are far beyond my level of comprehension. Maybe they don't have a clue what they are talking about, but it makes sense to me, but then again that may not mean anything!

Best of Luck,
M Richardson

 

[BobinNC]

Re: 308 vs 260

Capt:

Straight from the Hodgdon Data Manual

308 Win 175 Gr SMK Varget 45.6C gr 2728 FPS 59,500 PSI

260Rem 142 Gr SMK H-4350 44.5 gr 2735 FPS 58,000 PSI

These are typical loads for both rounds, and you be hard pressed to find two loads with near equal pressures, velocities, and powder charges. Yet, the 308 will show significantly longer barrel life than a 260.

Hint: it's not the velocity, nor the pressures, nor the different burning rates between the powders. It's the expansion ratio.......

regards,

Bob

 

[tylerw02]

Re: 308 vs 260

Correct me if I'm wrong, but isn't pressure more complicated than peak pressure published in a manual? Does peak pressure not occur past the throat?

 

[goober]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ch'e</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: problemchild</div><div class="ubbcode-body">Do the 260's burn out barrels quicker? </div></div>

More powder + smaller bore = yes

But just how long a 308 will outlast a 260 is anything but a concrete answer. The main answer is YOU have to weigh ALL the pros and cons and decide on what caliber is best for the purpose you have in mind.</div></div>







the real question should be....

will a .260 accuracy drop off faster than a .308....


answer: yes </div></div>

Boltripper please explain why the 260 accuracy falls of quicker than a 308 round -cheers </div></div>

OOOHH I thought boltripper was saying whilst in flight the bullet gets less accurate than a 308 -didnt realize we were talking barrel burn

 

[BobinNC]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tylerw02</div><div class="ubbcode-body">Correct me if I'm wrong, but isn't pressure more complicated than peak pressure published in a manual? Does peak pressure not occur past the throat? </div></div>

Tyler,

You might not be wrong, but since barrel wear mostly affects the throat area, any pressure generated down stream of the throat, cannot be wearing the barrel out.

The more I think about it, the more it sounds like a "hose nozzle" effect. Since pressures, velocities, and powder charges (though not burn rates), for a 260 Rem and 308 Win can be so similar, but the barrel life is not.

It stands to reason, even if I cannot prove it, that the hot gases and pressures generated from the neck of a 260 Rem, are more focused than the same gases, at the same pressure, from the neck of a 308. Hence a "hose nozzle" effect.....maybe????

 

[tylerw02]

Re: 308 vs 260

The pressure still exists in the throat, does it not? I think comparing solely maximum pressure misses the point, as maximum pressure doesn't occur at the throat necessarily. The gases still expand and fill their container, if I remember my physics correction. But you're on the right track as some cartridges funnel the expansion of gases and trap most of the initial, violent explosion within the cartridge. For instance, a .204 Ruger has BETTER barrel life than a .223, despite more velocity and pressure. Compare the 6mm Remington and the .243. Seems in many of the varminting magazines and other publications, the 6mm Rem outlives the .243.

I attribute that largely to sharper shoulders and a longer neck, much like described in the April-June 2007 issue of The Varmint Hunter. When drawing an extension of two imaginary lines, extending the shoulders at the same angle to their intersection point called a "turbulent point". If that intersection point is in the neck, the throat erosion will be at a slower rate because the cartridge itself contains the initial expansion of burning gases.

 

[Greg Langelius *]

Re: 308 vs 260

I run 142SMK, 43.8gr H-4350, 2850fps 28" barrel. Like I said, milder charges with longer barrels.

IMHO, barrel life is measured in total pounds of powder consumed.

 

[captrichardson]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BobinNC</div><div class="ubbcode-body">Capt:

Straight from the Hodgdon Data Manual

308 Win 175 Gr SMK Varget 45.6C gr 2728 FPS 59,500 PSI

260Rem 142 Gr SMK H-4350 44.5 gr 2735 FPS 58,000 PSI

These are typical loads for both rounds, and you be hard pressed to find two loads with near equal pressures, velocities, and powder charges. Yet, the 308 will show significantly longer barrel life than a 260.

Hint: it's not the velocity, nor the pressures, nor the different burning rates between the powders. It's the expansion ratio.......

regards,
Bob</div></div>

I am sure most people would agree, when it comes to loads, numbers can be all over the place, and what one person considers "typical", another would not. I would consider a 175 SMK going 2,700+ fps to be on the upper fast end, I would consider 2,550-2,600 fps more "typical". On the other hand, I would consider a 142 SMK load going 2,700 fps to be on the lower slow end, I would consider 2,800-2,850 fps to be more the norm. Of course are we talking Factory Ammo vs Handloads, 20" Barrels vs 28" Barrels, or "Conservative" or "Extreme" loads? I think this leads to a lot of the controversy with "Barrel Life", because someone may be comparing wear in a barrel shooting a conservative load to wear in a barrel shooting an extreme load. In my experiences, most .308 shooters are not typically pushing the envelope like most .260 shooters. This can lead someone shooting a 175 SMK out of a .308 at 2,550 fps to comparing barrel life to someone shooting a 142 SMK out of a .260 at 2,850 fps. That situation is really an “apples to oranges” comparison in many ways.

If you take the two loads you listed, which are a fairly close comparison, would barrel wear be the same, NO. Why?

As we have both pointed out, it is because the diameter of the bore on the .260 is smaller, which as you pointed out results in a “Low Expansion Ratio”. This leads to a “Focused Blow Torch Affect” as the gases are forced into a smaller opening, which is similar to the “Finger on the Garden Hose” analogy that I used. You are correct that a “Low Expansion Ratio” leads to barrel wear, but there is also a direct correlation to the Low Expansion Ratio and the resulting focused Pressure / Heat. Pressure / Heat destroy steel, Low Expansion Ratio, focuses that Pressure / Heat.

I am pretty sure that we agreed, I just don’t think that we were speaking the same language!

Thanks,
M Richardson

 

[vman]

Re: 308 vs 260

So, if you pushed a 175smk, and 155scenar, at the same pressure, but at different speeds... would these two identical and hypothetical barrels have the same life?

 

[turbo54]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: captrichardson</div><div class="ubbcode-body">
In my experiences, most .308 shooters are not typically pushing the envelope like most .260 shooters.</div></div>

Respectfully disagree.

Most any of us handloader types are doing load development that takes us to the pressure limits, then we back off a bit.

If anything, the .308 guys hot-rod their rifles more, because they are trying to get closer to the ballistics of the 6.5mm cartridges.

So far, the expansion ratio and shoulder angle intersection point theories seem the most sound and rational to me.

 

[captrichardson]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: captrichardson</div><div class="ubbcode-body">
In my experiences, most .308 shooters are not typically pushing the envelope like most .260 shooters.</div></div>

Respectfully disagree.

Most any of us handloader types are doing load development that takes us to the pressure limits, then we back off a bit.

If anything, the .308 guys hot-rod their rifles more, because they are trying to get closer to the ballistics of the 6.5mm cartridges.

So far, the expansion ratio and shoulder angle intersection point theories seem the most sound and rational to me. </div></div>

Key Word "Handloaders!"

Most .308 shooters I know are shooting out of a factory box, be it Military or LE, they really don't have any other choice! FGM 175 SMK and M118LR loads are only going around 2,600 fps.

I would agree that some .308 handloaders would "hot road" their loads to try and help with the ballistics, hence my comments about loads being all over the place.

If someone really wants to take a look at the science behind barrel "burnout/erosion" here is one for you:

http://www.riflebarrels.com/articles/barrel_life3.pdf

From that study, barrel erosion is the result of Chemical, Thermal, and Mechanical impacts on the steel. Our discusion here would obviously fall under the Thermal heading.

Thanks,
M Richardson

 

[turbo54]

Re: 308 vs 260

The context of this thread is tactical type/competition/high performance marksmanship.

In that context, MOST all shooters are loading their own ammo. When people (in this context) question barrel life, they want to know how 308 and 260 compare, when you are getting what you can out of the cartridge.

Thus, lame factory ammo does not apply here.

 

[crumpett]

Re: 308 vs 260

I apologize in advance if i am repeating a point that has already been discussed, but I think that the Turbulence point of these particular cartridges has a significant effect on how quickly throat erosion occurs and hence barel life suffers.

 

[johngfoster]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: captrichardson</div><div class="ubbcode-body">Most .308 shooters I know are shooting out of a factory box, be it Military or LE, they really don't have any other choice! FGM 175 SMK and M118LR loads are only going around 2,600 fps.

Thanks,
M Richardson </div></div>

In my 308, FGMM 175 SMK is running 2720fps (25" Bartlein SS barrel).

 

[Chanonry]

Re: 308 vs 260

hmmm

208's are superb with the right powder.

308 vs 260? its been done to death. lots of benefits to the 308, not enough benefits to a 260 to be seduced by it UNLESS it fits exactly.

You can buy a lot of 208's or 155 scenars for the price of another bangstick.

 

[MitchAlsup]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">So, if you pushed a 175smk, and 155scenar, at the same pressure <span style="color: #FF0000">curve</span>, but at different speeds... would these two identical and hypothetical barrels have the same life? </div></div>

I can only take a guess at this. With similar pressures and similar shank lengths, both wear functions (pressure, friction) on the barrel will be essentially the same.

 

[ryhag1]

Re: 308 vs 260

I would buy a copy of Bryan Litz book, Applied Ballistics for Long Range Shooting.

Worth the money and explains and answers just about every question one might have.

 

[VKC]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Paduan Learner</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: arsh1055</div><div class="ubbcode-body">Hey all.

I have done some research looking at ballistics programs etc.
My question, the .243 and .260 are flat shooting rounds out to a 1,000 yds. Flatter than .308, buck the wind better. Is there a bullet weight and type in .308 that will match the .243 & .260?

I appreciate any knowledge gain here.
Thanks,
Rob </div></div>

Why yes!! the 210grn Berger VLD.

Of course you have to shoot it out of a .300WinMag, with at least a 26" barrel. But it WILL match the .243 and .260. Or is that the .243 and .260 <span style="font-weight: bold">will</span> match the .300? I forget! </div></div>

He summed up my thoughts exactly.

The 260 remington was designed specifically to have a trajectory similar to a 300 win mag but with less recoil.

 

[VKC]

Re: 308 vs 260

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">So, if you pushed a 175smk, and 155scenar, at the same pressure <span style="color: #FF0000">curve</span>, but at different speeds... would these two identical and hypothetical barrels have the same life? </div></div>

I can only take a guess at this. With similar pressures and similar shank lengths, both wear functions (pressure, friction) on the barrel will be essentially the same. </div></div>

Almost but not quite, as a heavier bullet will tend to have more bearing surface.

 

[Flynn]

Re: 308 vs 260

I read this thread and found this to be interesting:
.308 comparison

It sounded objective enough and have lived and hunted in Alaska for several years..

I found the article interesting for it's real world application(s), not just target shooting..