Don't want to hijack 7RUMloaders post so I will keep this quick and simple.
The initial three Allen Mag rounds are the 257 Allen Mag, 6.5mm Allen Mag and the 270 Allen Mag.
The 257 and 6.5mm versions are based on a full length 338 RUM case with the shoulder sharpened and body taper reduced to very minimum. Case capacity when filled to the case mouth with the fine ball powder WC872 is in the 118 gr range.
The 270 Allen Mag, by far the easiest to form is based on the full length 7mm RUM case(0.100 longer then the 338 RUM) and again with the Allen Mag shoulder configuration. This round has a case capacity filled to the case mouth with WC872 of 125 gr compared to 117 gr for the 7mm RUM parent case.
The 257 and 6.5 Allen Mags have slighlty more case capacity then the longer full length 7mm and 300 RUM cases.
Here is a simple performance listing for the rounds with general bullet weights used in my 30" barreled Extreme Sporters:
257 Allen Mag
100 gr......4090 fps
130 gr......3650 fps
142 gr......3500 fps
156 gr......3350 fps
6.5mm Allen Mag
100 gr......4100 fps
120 gr......3800 fps
140 gr......3550 fps
155 gr......3375 fps
169.5 gr....3200 fps
270 Allen Mag
130 gr......3850 fps
169.5 gr....3380 fps
YOu will see some unusual bullet weights for these rounds. Yes 156 gr 257 bullet is correct!!! One of the aspects to these rounds that produce such amazing extreme range performance is the custom bullets Richard Graves or Wildcat Bullets has designed specifically for these extreme performance wildcats. They are also designed for use on game up to large deer as well. Here is a list of the BCs I have gotten from testing his bullets over 500 and 1000 yards:
257 100gr BCFBHP..........0.450
257 130gr BCFBHP..........0.550 J-4 jacket
257 130gr BCFBHP..........0.520 Heavy Jacket
257 142gr ULD RBBT........0.780
257 156gr ULD RBBT........0.820
270 169.5gr ULD RBBT......0.750
This summer there will be a fourth Allen Mag joining the group. This will be a 7mm version based on a different parent case. Performance should easily top what the 7.21 Firebird from Lazzeroni will produce. Richard is also hard at it designing bullets for this new monster 7mm. He has sent me prototype bullets that are a 200 gr ULD RBBT with an expected bc in the mid to high .9 range!!
We are looking to get 3200 fps with this bullet in a 30" barreled Extreme Sporter rifle.
These are all designed for the specific purpose of long to extreme range big game hunting and as such they offer barrel life long enough for a lifetime of big game hunting for even the most active big game hunter.
If you would like more details on the rounds such as pictures and information on the rifles and fild testing and range testing results with these new rounds drop me an e-mail at: