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270-338 RUM

 
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  #1  
Old 11-03-2004, 05:56 PM
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270-338 RUM

Anybody have any experience with this one? Case would be a 338 RUM necked down to the 270. If I would get one chambered, I would probably go with a 28" barrel. With this combo I would hope to drive a 150 grain bullet at 3400-3500 fps. Any comments, experiences, suggestions?
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  #2  
Old 11-03-2004, 06:12 PM
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Re: 270-338 RUM

Did you read this post about "Allen's"? http://www.longrangehunting.com/cgi-...c&f=3&t=002521

IMO - Cases that can hold 120 grains of powder have a very limited uses. I have a wildcat 7mm STW so it's slightly bigger than the production model. I can make 3300 fps with 160 grain bullets with only 80 or so grains of powder and have nice case life.

I would think a 270 STW would be a fine weapon and not give up that may fps to the super cannons. That's why i use such long barrels
[img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]
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.270 Ackley improved 29 inch 1.250 dia. target barrel 7mm STW 28 inch 1.250 target barrel. I also love my .458 mag for varmints and the biggest game in the world.
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  #3  
Old 11-03-2004, 07:03 PM
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Re: 270-338 RUM

Thanks for the heads up, very interesting.
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  #4  
Old 11-03-2004, 10:35 PM
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Re: 270-338 RUM

7Ultra,

I am designing and releasing a family of rounds based on the 338 RUM case. They will include the 257, 6.5mm and 270.

My rounds named the Allen Magnums will be modified quite heavily compared to the standard 338 RUM parent case.

These rounds are being designed along with Richard Graves of Wildcat Bullets in Alberta Canada who is designing some very impressive bullets for these new rounds.

Just a few of them are the four new options for the 257 AM. A 130 gr Bonded Core FBHP, 145 gr FBSP, 150 gr FBHP and a 145 gr Rebated Boattail ULD design.

For the 6.5mm version there will be the 140 gr Bonded Core FBHP, a 160 gr class RBT ULD and this winter we will be designing a 180 gr ULD for the 6.5 AM.

The 270 version will also have new bullets but of more traditional weights such as 130 gr but also aome heavy 169 gr pills as well.

The AM case will be the largest practical case for thes rounds and substantially more then the parent case 338 RUM simply necked down.

The trick is to use heavy bullets to make this big case run hard.

About the 338 RUM having 120 gr of usable powder volume, this simply is not true by any means.

Comparing the 257 STW, 257 AM and the 25 RUM, the case capacities are as follows when filled to the case mouth with H-335:

STW: 104 gr
AM: 120 gr
RUM: 128 gr

Now if you compare usible powder capacity, its more like:

STW: 80 gr
AM: 95 gr
RUM: 105 gr

This is filled to the base of the neck. This is certainly alot of powder espeically if you plan on using light for caliber bullets but for the heavy for caliber bullets this case size will perform very well in a barrel length that you want to use.

My AM rounds are designed around 30" barrels.

Good Shooting!!

Kirby Allen(50)
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #5  
Old 11-04-2004, 08:55 AM
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Re: 270-338 RUM

Fiftydriver - I'm proud of the work your doing. One of my friends bought one of the first 30-378's to come out. I was very impressed when we got into the Chrono work. It made the 300 win mag. look like a 30-30 compared to 30-06

I like the idea of your middle of the road approach between STW and RUM.

So little time and so many choices!!!!!!!!!!
[img]images/icons/smile.gif[/img]
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.270 Ackley improved 29 inch 1.250 dia. target barrel 7mm STW 28 inch 1.250 target barrel. I also love my .458 mag for varmints and the biggest game in the world.
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  #6  
Old 11-04-2004, 06:53 PM
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Re: 270-338 RUM

Fiftydriver,
Those are definately some very interesting cartridges. You've definately got my attention. But for the rifle I have in mind, I want to keep it as moderate (10-12lbs) and mobile as possible. What do you think the longest barrel, given this criteria, would be best while still utilizing the cartridges capabilities. Specifically, I want a tube that is going to have a fair amount of rigidity and not have to be hung off of a barrel block. Thanks for the info, agian it's definately got my attention.
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  #7  
Old 11-04-2004, 11:42 PM
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Re: 270-338 RUM

7Ultra,

All the prototype(if you will) AM rifles I will be building will be using a #6 contour Lilja Stainless steel barrel of 30".

As I said, these are designed as hunting rifle, that being, carry rifles for use in open country where the 30" pipe will not be a bother.

I have used my wifes 257 STW built on this same configuration, in fact it is the rifle I used to take my whitetail this year. This rifle is inthe 9.5 lb range ready to hunt with this barrel length and contour and I am getting 1 1/4" three shot groups at 500 yards so the stability and rigidity must be there.

Also this barrel is totally floated. This was kind of an experiment to see how the #6, 30" barrel would perform as far as barrel flip was concerned. I do not see a problem as of yet and do not expect to.

The barrel that is on order for the 257 AM is another #6 contoured Lilja Stainless 30" blank. The only difference is that I had Dan flute this barrel with the larger diameter flutes designed for the 50 BMG barrels.

What this will do is give me the stiffness and rigidity of the #6 contour which is obviously working with a barrel weight slightly less then a #5 contour barrel. Put another way, I will be able to cut 1/2 lb off the rifle weight compared to my wifes 257 STW.

I will also be using a Holland Signature Series Laminated stock which is about 1/4 lb less then the Boyds Thumbhole sporter I fitted to my wifes rifle.

These are certainly portable rifles that will easily be under the 10 lb range.

As you know there is always some sacrifice in accuracy trading rifle weight for portability, at least at a certain point.

I am looking to build rifles that will perform as a portable rifle that will allow the hunter to engage deer size game, up to 500 lbs even, at ranges out to 500 yards without major sight adjustment.

Here are a couple pics of her rifle. The three initial AM rifles will look similar to this but will have the heavy flutes and a traditional sporter Laminated wood stock.





One could also go with one of the light weight composite stock as get down to very light rifle weights for a 30" barrel.

I feel the #6 contour is as light as I would go out to a full 30" and still be comforatble with rigidity with these rounds.

Again, with this barrel weight, there is no need for exotic bedding systems, just a quality pillar bedding job is plenty to support this barrel length on a Rem 700 action in my opinion.

Good Shooting!!

Kirby Allen(50)
__________________
Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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