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More 257 Allen Magnum range results....

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Unread 01-25-2005, 02:53 PM
Junior Member
Join Date: Jan 2005
Location: Howard , CO
Posts: 12
Re: More 257 Allen Magnum range results....

wow, very impressive post Mr Allen. I have been considering building a longrange shooter on the .257 cal. Would you explain what the parent case is for your 257 magnum? thanks in advance.
good shooting, AJ
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Unread 01-25-2005, 06:23 PM
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Join Date: Jun 2004
Location: Fort Shaw, Montana
Posts: 6,848
Re: More 257 Allen Magnum range results....


My 257 Allen Magnum and the 6.5mm Allen Magnum are based on the full length 338 RUM case. This case is 0.100" shorter then the other RUM rounds and as such offered the maximum usable case capacity. The shorter case holds about 8 gr less then then say a 7mm RUM fireformed to teh Allen Mag shoulder configuration.

The case is nearly absent of body taper, about 0.008" over teh entire length of the case body. The shoulder angle is also increased substantially over that of the 338 RUM but not quite to Ackleys 40 degree shoulder.

CAe capacity filled to the mouth with H-335(settles evenly) measured 123 gr.

I am offering pre neck sized cases that will be properly sized and then annealed as the brass is work hardened quite severely going from 338 to 257.

The necked down and annealed cases will run $38.00 per 50 cases plus shipping. All that will be needed is to load a fireformign charge and shoot. Then trim and your ready for full tilt loading.

Because this round is such an extreme performance round, there has only been one powder that has produced excellent results with all bullet weights tested including the 100, 115, 130, 145 and 156 gr bullet weights. That powder is AA 8700.

The bad thing is your limited to one powder, the good thing is it works great with all bullet weights and is much cheaper then most reloading powders on the market.

This powder will drive a 100 gr pill to 4100 fps with groups in the .3"s as well as drive the huge 156 gr ULD bullets to +3350 fps in one of my 30" Extreme Sporter rifles.

Using this huge 257 bullet, this will make an excellent extreme range rifle as it has a B.C. higher then a 300 gr Sierra Mk .338" bullet and can be launched 250 fps faster then even the 338-378 Wby can drive the 300 gr pill.

This bullet will stay supersonic past the 2000 yard mark easily.

I will be building myself one of my V-Block rifles in this caliber probably this summer.

Lilja will be making the 1-10 and 1-7.5" twist barrels for the 257 AM.

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

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