Question for FIFTY (Kirby Allen)????

[Fiftydriver]

Would just like to make one correction to your post. The actual BC of the 142 gr ULD RBBT in 25 cal is more on lines with 0.700.

With this number the two Allen Mags, 257 and 270 loaded with the 142 and 169.5 gr ULD RBBTs are pretty much ballistic twins.

It is true the 156 gr ULD RBBT has a higher BC then the 169.5 gr ULD RBBT 270 bullet but in my testing it will top out around 3300 fps with a comfortable load compared to nearly 3400 fps or a bit more in some cases with the 270 AM.

This is all besides the point anyway, I do not recommend either one of these for any type of varmint hunting use. They can certainly be used for that but the user must realize that barrel life is limited anyway and when used in such a role either will be very hard on a barrel.

As a big game rifle they will last many many seasons and in most cases a lifetime of serious big game hunting.

They are both extreme performance rounds. The 270 has the dramatic advantage in user friendliness as far as case forming and loading. The 257 AM is on the very top of the 25 cal performance pile and as such is a very extreme and sometimes finicky round with special limitations in powders that can be used to load her.

Just wanted to offer my opinion between the comparision.

Kirby Allen(50)

 

[wildcat]

Thanks for the info Scott. The 257 AM sounds like the way to go, however, I am still trying to make up my mind.

 

[scott]

No problem Wildcat, FiftyDriver knows more about it than I do, and I was wrong about the BC of the 142 ULD...
FiftyDriver says he has gotten 3500 fps from a 1:7 with the 142 ULD in the 257, but I would be the 9 twist would do much better....
With the 257 AM you are stuck with Ball powders, they can be somewhat temp sensitive.. meaning.... you might lose 200 fps from 60 deg to 20 deg.. I am just throwing a number... but I have heard they are temp sensitive in velocity... at 700-800 yards, it could make a differance...
Still a .700 BC bullet at 3500-3600 fps isn't going to drift much at real long range... Doping with the wind can be tricky...

Fifty is right, not a good Varmit gun, if the varmits are prarrie dogs or woodchucks, but Varmits like coyotes that are not quite as plentiful... maybe a good gun
Where I live, it would make a good Yote gun... We maybe see 2-3 Coyotes a year, heck I haven't shot at once in over 2 years...
my next gun will either be a 257 AM or probably a 6mm284 to shoot 105's for coyotes at range.

good luck
scotty

 

[THOMAST]

Fiftydriver - what is the parent case for the 257 AM and the 270 AM?

 

[Fiftydriver]

The 257 AM is based on the full length 338 RUM and the 270 AM uses either the 7mm RUM or 300 RUM.

As such, the 270 AM is roughly 0.100" longer then the 257 AM and holds about 8 grains more powder as well.

Kirby Allen(50)

 

[davewilson]

just build him a 6WSM with a 12 or 14 twist so he can shoot those v-max bullets! that would be "mist factor"

 

[Fiftydriver]

Dave,

How about a 6.5mm WSM loaded with some 100 gr Ballistic Tips? POP goes the P. dogs!!! /ubbthreads/images/graemlins/grin.gif

Kirby Allen(50)

 

[41mag]

Yep and if your varmints are like ours "Prairie Hogs" instead of "Dogs" that .270 AM is the way to go definately. And similar to what Kirby mentioned, Pop goes the Prairie Hog....

I can hardly wait till cool weather and they are more on the move than now. I will definately have them dialed in by then and see some dramatic mist factor results. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

I can inject this however, I had this rifle built for a specific purpose and chose this caliber based on several decisions. One was the fact I had a butt load of 150gr Noslers sitting here that were never going to be shot, another was the velocities and range of this particular rig, another was the ease of finding and assembling the components.

If I ever build another similar rig, I am already leaning towards the 338 Edge, or similar rounds. On the other hand, a custom 300 RUM would also suit my needs very well indeed.

For now though, I am slowly working into getting the most out of the .270, and hopefully by years end will have at least one or two hogs at ranges beyong 1K. I have no doubt that a properly placed 169.5gr Wildcat at somewhere between 3200 and 3300fps will do it's job when it gets to the intended target.

 

[robbor]

Hey Kirby, I just have to stand up here. AM's are not for varmint's and should be used for big game. Didnt you just shoot a chimpmunk on steroids at 2300 yards/ubbthreads/images/graemlins/grin.gif???

 

[Fiftydriver]

Yep,

But I only took four shots at it as well, then took her home and cleaned her good, stroked the barrel several time chanting "good girl, good girl!!!" and then knocked on wood several times and killed a spider as a sacrifice to the shooting gods for my good foutune!!! /ubbthreads/images/graemlins/grin.gif

All kidding aside, for high volume shooting I do not recommend any of my Allen Magnums for this use.

If your taking limited, deliberate shots at varmints at long range, go for it!!

Kirby Allen(50)