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  #1  
Old 08-25-2007, 04:37 PM
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270/08 Wildcat


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Dear all, this in my first message as I have just become a member 2 minutes ago!

I am thinking of building a 270/08 ( using standard 20 degree shoulder, ie 7mm/08 cases necked down at accept .270 bullets )

What barrel length would you guys recommed?
I,m thinking about a twenty four and a half inch barrel, with a 1:10 twist!

I will be building the rifle on a Howa action.

I live in Australia, and will be using the Rifle on Pigs, Goats and Fallow Deer
I also invite and load data and I have it in mind to use Nosler 130 grain Ballistic Tips to start with
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  #2  
Old 08-25-2007, 08:26 PM
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I'm not a wildcatter...but the Q comes to mind why?

I'm thinking that there wouldn't be a nickle's difference (5 cents) between it and either the .270 and/or the 7mm-08 and you can buy both of those all over the place.

The reason you wild-cat (again I don't do it) is to get an improvement on what is on the shelf. Say a .270 AI or an 08 improved (which are not much of an improvement...especially compared to the .280) make more sense

I don't think that it is logical.
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  #3  
Old 08-25-2007, 08:35 PM
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Hi Dale and welcome to the forum...

The 270-08 is a fairly popular round as is it's bigger cousin, the 270-284...

Here are a couple of loads that I have loaded for the 270-08 using Noslers 130 gr. Ballistic Tip...

CASE: W-W 7mm-08 necked down to 270-08

PRIMER: CCI-200

POWDER: IMR-4350 / 46.0 gr.

BULLET: Nosler 130 gr. Ballistic Tip

VELOCITY: 2,890 fps.

.................................................. .................................................. ..............

CASE: W-W 7mm-08 necked down to 270-08

PRIMER: CCI-200

POWDER: IMR-4831 / 46.0 gr.

BULLET: Nosler 130 gr. Ballistic Tip

VELOCITY: 2,762 fps.

Both velocities listed are from 22" barrels...


Both loads have been fired in various 270-08 barrels and were perfectly safe but as always, start at least 10% lower than listed load and work up gradually, watching for signs of excessive pressure...

Your barrel length should be just fine for this cartridge as should the 1-10" twist and the 130 gr. Ballistic Tip for busting pigs, goats and fallow deer....

A
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  #4  
Old 09-22-2007, 12:53 PM
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Quote:
Originally Posted by ASSASSIN
Hi Dale and welcome to the forum...

The 270-08 is a fairly popular round as is it's bigger cousin, the 270-284...

Here are a couple of loads that I have loaded for the 270-08 using Noslers 130 gr. Ballistic Tip...

CASE: W-W 7mm-08 necked down to 270-08

PRIMER: CCI-200

POWDER: IMR-4350 / 46.0 gr.

BULLET: Nosler 130 gr. Ballistic Tip

VELOCITY: 2,890 fps.

.................................................. .................................................. ..............

CASE: W-W 7mm-08 necked down to 270-08

PRIMER: CCI-200

POWDER: IMR-4831 / 46.0 gr.

BULLET: Nosler 130 gr. Ballistic Tip

VELOCITY: 2,762 fps.

Both velocities listed are from 22" barrels...


Both loads have been fired in various 270-08 barrels and were perfectly safe but as always, start at least 10% lower than listed load and work up gradually, watching for signs of excessive pressure...

Your barrel length should be just fine for this cartridge as should the 1-10" twist and the 130 gr. Ballistic Tip for busting pigs, goats and fallow deer....

A
Guys, I was googling the .270-08 and that's what brought me to this site and this post. (I now am a member here.)

I need HELP comparing the ballistics of the 270.08 and the .260. Need your opinions contrasting the two calibers. Need your opinions on the two in target shooting (F Class) as well as wild game.

Let me be more candid. I'm stuck in a position of having to offer advice on these two calibers and know a 'little' about the .260* and nada about the 270-08.



Warthogg


*As an example, I know the .260 will remain supersonic all the way to a 1000 yard target.
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  #5  
Old 09-22-2007, 03:40 PM
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Warthogg,

The 6.5 bullets usually have a higher ballistic coefficient and sectional density over that of the 270 and as such, for long-range shooting, the 260 will have a slight advantage over the 270-08...

The main thing I have noticed about the 260 round or any 6.5 caliber for that matter is that you need to first decide on what bullet weight range you are wanting to shoot and then match your barrels twist rate accordingly. With the 270-08, a 1-10" twist rate will cover all bullet weights from 110 gr. up to 150 grains with excellent accuracy for all weights...

With loading die availability and the inherant accuracy of the 260 Remington, for both game and targets, I think the 260 would be a better choice. Like I said before though, match the twist rate to the bullet weight range you want to shoot...

By the way, welcome to the forum and God Bless....

A
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  #6  
Old 09-22-2007, 04:05 PM
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Like it's parent case, a 20 inch varmit wgt bbl would suffice and give you a little more repeatability when shooting more than one round. Trade the 24 for the 20 hvy bbl, you won't notice the wgt difference littly handier in the bush.
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  #7  
Old 09-22-2007, 04:34 PM
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Quote:
Originally Posted by Swany
Like it's parent case, a 20 inch varmit wgt bbl would suffice and give you a little more repeatability when shooting more than one round. Trade the 24 for the 20 hvy bbl, you won't notice the wgt difference littly handier in the bush.
Re barrel twist bullet weight, I've been a believer for a good many years now.

In 5.56/.223, the 1:9 twist will handle a vareity of bullet weight but the accuracy sweet spot is 69 grns.
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  #8  
Old 09-25-2007, 01:12 PM
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Quote:
Originally Posted by stinky
I'm not a wildcatter...but the Q comes to mind why?

I'm thinking that there wouldn't be a nickle's difference (5 cents) between it and either the .270 and/or the 7mm-08 and you can buy both of those all over the place.

The reason you wild-cat (again I don't do it) is to get an improvement on what is on the shelf. Say a .270 AI or an 08 improved (which are not much of an improvement...especially compared to the .280) make more sense

I don't think that it is logical.
stinky,

points well taken.

The .270 casing and bullet is too long to fit in the particular weapon I have in mind. Soooo.......in the .260 or the 270-08, improvement would be had but improvement over the .308 and I can ONLY choose between the .260 and the .270-08..

Improvement over the standard .308 is what I'm after.

W.Hogg
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  #9  
Old 09-26-2007, 02:11 AM
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Quote:
Originally Posted by Warthogg
stinky,

points well taken.

The .270 casing and bullet is too long to fit in the particular weapon I have in mind. Soooo.......in the .260 or the 270-08, improvement would be had but improvement over the .308 and I can ONLY choose between the .260 and the .270-08..

Improvement over the standard .308 is what I'm after.

W.Hogg

7MM/08 ACK IMP OR 270/08 ACK IMP Both will leave the 308 for dead for sure
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  #10  
Old 09-26-2007, 06:03 AM
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Quote:
Originally Posted by rock hard
7MM/08 ACK IMP OR 270/08 ACK IMP Both will leave the 308 for dead for sure
Sooooooooo, now to find out about the .270-08 ACK IMP.







WartH.

Last edited by Warthogg; 09-26-2007 at 02:13 PM.
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  #11  
Old 09-26-2007, 07:06 AM
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WartH, when considering any wildcat, there are three rules of thumb that you can use to very closely predict performance. All use two constants and one variable.

* If case capacity and bore size are constant, potential velocity varies inversely at one half the percentage change of bullet weight.

* If case capacity and bullet weight are constant, potential velocity varies at one fourth the percentage change of bore area.

* If bore size and bullet weight are constant, potential velocity varies at one fourth the percentage change of case capacity.

The wildcat you are considering changes the bore size, so let's compute a bit. A .264" bore has a cross sectional area (bullet base) of .055 Sq in, and a .277 bore has .060 Sq in. The .264 is 8% smaller, so a same-weight bullet in the .270-08 will have a muzzle velocity of 2% more. Why? because the gas has slightly more "piston" area to push on and the shorter bullet of the same weight will have less friction.

Whether that slightly higher velocity (if we assume 2800 fps, 2% is only a 56 fps gain) is offset by lower sectional density is up to you to decide.

BTW. the third rule is why the so-called "Ackley Improved" rounds aren't all that much improved at all. Blowing out a case to get an 8% volume improvement (which is about average), gives you only about that same 56 fps boost UNLESS YOU LOAD TO HIGHER PRESSURES. Anybody who boasts that his fabulous new AI chamber gives him 200 fps more than the parent chamber is running the round at significantly higher pressures, plain and simple. Unless he also changed the powder to magic pixie dust.

This usually starts a firestorm with AI lovers, but science is science and opinions are only opinions.
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Last edited by Rocky Raab; 09-26-2007 at 07:11 AM.
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  #12  
Old 09-26-2007, 09:31 AM
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Believe Rocky is correct in the above. Have been an AI fan for some years and have noticed the best advantage is case longivity. The normal 4 to 5 percent increase in velocity is accomplished by the equal amount of increased powder charge.

Guess I'm coming full cycle, but of late have taken more and more to the old standard cartridges and trying to develop better loads with the newer powders and bullets that are available.
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  #13  
Old 09-26-2007, 10:16 AM
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In fact, when you blow a case out, you have to increase the charge weight a bit just to get back to the ORIGINAL velocity. That often takes up most of the volume you gained.

The only advantage I've seen in AI cases is that they don't tend to stretch as much. But that's all.
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  #14  
Old 09-26-2007, 10:22 AM
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Quote:
Originally Posted by Rocky Raab
In fact, when you blow a case out, you have to increase the charge weight a bit just to get back to the ORIGINAL velocity. That often takes up most of the volume you gained.

The only advantage I've seen in AI cases is that they don't tend to stretch as much. But that's all.

This is getting scary.

You folks are so good at explaining that I fear I'm actually beginning to undesrsatnd !!

Wart
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  #15  
Old 09-26-2007, 11:28 AM
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You are treading into a hazardous situation. Remember the 280 Rem has a longer case body length so that the 280 CANNOT be loaded into a 270 chamber. When Winchester came out with the 7mm and 277 Magnum short cases, they had a recall to modify the 7mm chambers so that the 7mm could not be loaded into the 277 chamber. What happens when you(or more so a new owner) size 7mm-08 cases for your 270-308 and inadvertantly forces a 7-08 into the 277 chamber. Your future grandson may empty his skull at the shooting bench. I'd say forget the interest in this venture. Ackley Improving won't do a thing to alleviate this problem.
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  #16  
Old 09-26-2007, 01:01 PM
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Uh huh, that's the problem of mismatched headstamps. Going one step down is fine if somebody somewhere loads a .270-08 cartridge (that they found on the ground) into their 7mm-08 rifle, there isn't likely to be a problem other than wondering why it went "Blooop" instead of "Boom!"

But if you necked up from a .260 and somebody found one, they just conceivably might be able to cram your .270-08 into their large-tolerance rifle's chamber. Pressures would be high, but I doubt that anything other than the shooter's bowels would let go.

That's why I always neck down. I make my .25-308 cases from 7-08 brass (I started making it before they came out with the .260) and won't buy a 7-08 rifle just to be sure. With WW brass, I can even use .308s to make .25-308 - Federal brass is too thick in the neck.
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  #17  
Old 09-27-2007, 12:05 PM
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The necks are to thick on 308 Federal brass to use in my 7mm-08 which aggravates me because I have a bunch of it.
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  #18  
Old 09-27-2007, 12:11 PM
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Do you have a way to inside neck ream or turn the case necks?

A
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  #19  
Old 09-27-2007, 02:42 PM
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If Trailblazer is like me, we'd rather pee into a wall outlet than turn case necks.
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  #20  
Old 09-29-2007, 06:48 AM
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Well put, Rocky. I do have a way to turn them but I also have other brass that works w/o turning so it hasn't come to that.
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