Grendel at extended ranges?

[JASmith]

I've had discussions with others about the impact of shoulder angle and neck length on barrel life. Of the two, my intuition suggests that neck length is the more credible.

As a consequence, I would want to see a side-by-side comparison between the .260 and the Creedmore where they are both fed high-end fodder through the lifetimes of their barrels. For now, it seems the cost and availability of brass makes the .260 slightly more attractive.

[LRRPF52]

I've had discussions with others about the impact of shoulder angle and neck length on barrel life. Of the two, my intuition suggests that neck length is the more credible.

As a consequence, I would want to see a side-by-side comparison between the .260 and the Creedmore where they are both fed high-end fodder through the lifetimes of their barrels. For now, it seems the cost and availability of brass makes the .260 slightly more attractive.

So would a longer neck reduce throat erosion, or vice versa? Maybe a longer neck would soak up more heat than a short neck?

[JASmith]

The idea is the brass would would take the beating rather than the first part of the barrel.

Again, not sure it would make enough of a difference to make a difference when the neck is longer than about a caliber. One way to find out is to scope the bore and see where the erosion is worst.

[bwaites]

3000 rounds of barrel life is where I'm getting interested. I have a 7mm WSM for a barrel burner, the Grendel for really long life, and I've decided that rather than go to .308 for its long barrel life, I'm going to do another bolt action in a 6.5 of some sort.

From what I read, Bob is simply saying that the Hornady is a better buy when you look at cost per shot fired comparing the two.

I haven't been happy with Hornady brass in the Grendel, but maybe with the Creedmoor its a better deal.

[stokesrj]

I'm really saying that in theory the 6.5 Creedmoor is going to provide longer barrel life and longer brass life, I don't know this to be true but will be able to say for sure by the end of this year. I have a Tubb 2K in 6.5 Creedmoor with only 700 rounds down the tube which means it is barely broken in. I also have a set of brass with only four firings. So I don't know just how true the theory is. But I can say that I have it on good authority that the 6.5 Creedmoor will substantially outlast the .260 and give better performance while doing so. My source is Carl Bernowsky, who if your aren't in to high power won't mean anything to you, if you are, then you will know he is the National Champion for nine years. http://www.nrablog.com/post/2011/08/14/C...nship.aspx

[LRRPF52]

I've heard that the Creedmoor is easier to get to shoot, but barrel quality seems like the biggest factor here again. I get great results with my auto-loader .260 Rem, and have seen some guys who get 1-hole groups for 5 rounds with Krieger barrels and Berger VLD's, which is not supposed to be possible in auto-loaders according to what many have said about the Bergers in gas guns.

I'm getting great brass life out of necked-down Winchester 7mm-08 brass, and I've run it way hotter than I should have. I'm just barely starting to get into my Lapua brass, so we'll see how it goes. This whole Optimum Barrel Time concept is making me look for quicker ways to tune into my accuracy nodes with the different bullets I have.

[stokesrj]

I agree whole heartedly barrel qualitiy trumps most other considerations. I'm also sure the .260 is accurate enough or the AMU would not be using it. In High Power competiton once you achieve 1/2 MOA there is no need to look for more accuarcy. but it would be nice if the Creedmoor gives another thousand rounds per barrel, in theory it does, I'll have to wait and see if theory and practice agree.
Bob

[JASmith]

Let's compare case dimensions and bore capacity:

6.5 Creedmoor: Shoulder 30 deg; Neck Length 0.2852 in.; Case Volume 52.4 gr H2O; Bore Capacity 1.6
260 Remington: Shoulder 20 deg; Neck Length 0..2595 in.; Case Volume 54.8 gr H2O; Bore Capacity 1.7

The term "Bore Capacity" is defined at the end of the thread at http://www.gunandgame.com/forums/general...ion-2.html. The barrel is defined to be at bore capacity when the case volume gives one grain of powder per square millimeter of throat area. The note indicates that doubling the bore capacity reduces observed barrel life to about 1/4 of that of the .308 Win & .223 Rem cartridges. Nothing was said about neck length and shoulder angle.

Using this relationship suggests that the 6.5 Creedmore might see 10% more barrel life than the .260 Remington. Using the 3000 rounds generally seen by precision shooters of the .308 and .223, we could expect a difference in barrel life of about 150 rounds out of a total of about 1700 for the two.

Is this enough to make up for the difference in component costs?

[txgunner00]

Let's compare case dimensions and bore capacity:

6.5 Creedmoor: Shoulder 30 deg; Neck Length 0.2852 in.; Case Volume 52.4 gr H2O; Bore Capacity 1.6
260 Remington: Shoulder 20 deg; Neck Length 0..2595 in.; Case Volume 54.8 gr H2O; Bore Capacity 1.7

The term "Bore Capacity" is defined at the end of the thread at http://www.gunandgame.com/forums/general...ion-2.html. The barrel is defined to be at bore capacity when the case volume gives one grain of powder per square millimeter of throat area. The note indicates that doubling the bore capacity reduces observed barrel life to about 1/4 of that of the .308 Win & .223 Rem cartridges. Nothing was said about neck length and shoulder angle.

Using this relationship suggests that the 6.5 Creedmore might see 10% more barrel life than the .260 Remington. Using the 3000 rounds generally seen by precision shooters of the .308 and .223, we could expect a difference in barrel life of about 150 rounds out of a total of about 1700 for the two.

Is this enough to make up for the difference in component costs?

Sounds like an SAT question is in there somewhere...

What would the assumptions be for average brass life? There wouldn't be much if any difference in cost for the rest of the components.

Midway prices mostly

6.5 Creedmore brass-

$32/50 for Hornady,
[SIZE="1"]$110/100 for Lapua[/SIZE]. scratch that- wasn't supposed to be here

260 Rem. brass-

$53/100 for Rem,
$50/50 for Nosler
$110/100 for Lapua
$107/100 for Norma

Once fired .308 brass- ???

[LRRPF52]

You can also do:

$25/50 Winchester 7mm-08 Brass, necked down for .260 Rem Sizing the cases feels like sizing a once-fired .260 case, and is very straightforward. I have yet to neck-trim, and I have done at least 5 loads on my 7mm-08 brass.

I think that is the 3rd-best brass available for .260 Rem, with Sako brass being 2nd, and Lapua 1st. I have only seen the Sako brass in Finland, and it looks and feels like Lapua brass.

[bwaites]

Sounds like an SAT question is in there somewhere...

What would the assumptions be for average brass life? There wouldn't be much if any difference in cost for the rest of the components.

Midway prices mostly

6.5 Creedmore brass-

$32/50 for Hornady,
$110/100 for Lapua.

260 Rem. brass-

$53/100 for Rem,
$50/50 for Nosler
$110/100 for Lapua
$107/100 for Norma

Once fired .308 brass- ???

Lapua is doing Creedmoor brass now? That is cool!

[LRRPF52]

Lapua is doing Creedmoor brass now? That is cool!

Pretty sure they're not. I think he was just comparing prices. Lapua already has the 6.5x47 and the .260 Rem, and it took years of people begging for the .260 Rem and market demand to get them to do it.

[stokesrj]

Hornady claims that their 6.5 Creedmoor brass will outlast Lapua brass because it is softer and doesn't work harden as quickly. Again, I have only four firings on mine so I don't yet know if this is a reasonable asertion or not, I kind of doubt it.

I buy my 6.5 Creedmoor brass from Powder Valley for $30/50 or a unit cost of $0.60. If I get four firings the brass cost is $0.15 per shot. If I get eight it will be $0.075 per shot and if I get 12 firings it will be $0.05 per shot for brass only.
I know competitiors who have gotten 4,000 rounds out of their Schieder barrels with the 6.5 Creedmoor and around 3,000 rounds with their .260. You can't draw too much of a conclusion around this because I've seen that much variation with the same make of barrel and same caliber but is the best information availabel to me and if true then the cost per shot could be as low as the cost of a new barrel $680 divided by 4,000 which is $0.17 per shot for the 6.5 Creedmoor and $0.23 per shot for the .260.
Brass for the .260 is higher quality by a significant margin based on my experiences with other calibers using Lapua brass and 12 firings per case are pretty normal. At Powder Valley I can buy Lapua Brass for $92.30/100 or $0.923 per case dividede by 12 is $0.077 per shot.

The cost of shooting each caliber in terms of barrel wear and brass life with the above assumptions and assuming 12 reloads per case for the .260 and 8 for the 6.5;
.260 = 0.077+0.23= $0.277
6.5 Creedmoor =0.075+0.17=$0.245
Difference = .277-.245=$0.032

That doesn't sound like much and could easily be swamped by other factors or incorrect assumptions, still I shoot around 14,000 rounds a year in competitons so that would add up to $448. Another way of looking at it is I could afford to shoot one more match per year.

Bob

[txgunner00]

Lapua is doing Creedmoor brass now? That is cool!

No- sorry. Cut & past error.

[JASmith]

It appears that the cost of components is slightly in favor of the .260 and in barrels slightly in favor of the Creedmoor. At $400-$500 per barrel, and roughly 15 matches plus a couple of hundred rounds for load development and practice, the two cost numbers seem to offset each other. One could squeze one, maybe two, more matches out of the Creedmore if we assume the rule of thumb from a few posts earlier holds true.

One thing about the Creedmore vs .260: The Creedmore looks more like a grown-up Grendel (I think others made this observation, which must be why i'm thinking about it now!)

[txgunner00]

It seems to me the Creedmore has the edge for a match gun where it's easy to find and save your brass. The advantage would shift to the .260 for a field/ hunting gun.

[stokesrj]

That's kind of how I think about it as well, I have a couple of .260 hunting rifles, but if I build another I will go with the Creedmoor. To begin with, you can buy really accurate factory ammo for the Creedmoor, I haven't found any factory loads for the .260 that shoots worth a flip. That isn't much of a factor to me because I've almost always used reloads for hunting anyway, but it is nice to know you can get factory loads if you need to. Probably not at your local 7/11 though.
Bob

[ss355]

I'll chime in because I just took the Creedmoor plunge with a factory DPMS. I was tempted by the 260, particularly because LRRPF52 is a proponent and made some good arguments, but in the end I went 6.5 CM because Hornday makes match ammo at a reasonable price. I do reload, but life doesn't always afford me the time at the reloading bench that I'd like, so it is important to me to be able to buy a few boxes of quality, factory ammo on occasion. I know that Federal is coming out with a GMM 260 load, but dang, they're proud of their GMM offerings. Just yesterday I picked up a few boxes of 6.5 CM 140 grn locally for $21 apiece (oddly enough, from 7/11). With tax, that comes out to $1.13 a round, and I'll reload the brass. Heck, if that price holds, I probably won't buy any empty brass for reloading.

I've read reviews of the DPMS 6.5 CM, and most users reported what I thought were impressive results. For a sub $1K gun and factory ammo, I'm pretty pleased. Here's a group at 100 from the first box of ammo I put through the gun, and this was from a poor rest with the less-than-ideal factory trigger:



Soon as my scope comes in I'll take her to longer range and report to the horde.

[txgunner00]

Nice shooting

[LRRPF52]

That is sweet. I also noticed recently the prices on Hornady Creedmoor box ammo, and they have them priced to sell for sure. Also, for a factory DPMS, you got a good barrel if it consistently groups like that. Some of those barrels group in the teens, and others will give you 1.5" groups consistently-you just don't know what you're getting until you pull the trigger.

If Hornady continues to support the Creedmoor the way they are, it will likely not go the way of the gun like the 30 TC did. Most people haven't even heard of the 30 TC, which is the parent case for the Creedmoor.