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Final range test before the pronghorn season opens in the morning....

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Unread 10-08-2005, 01:37 PM
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Join Date: Jun 2004
Location: Fort Shaw, Montana
Posts: 6,848
Final range test before the pronghorn season opens in the morning....

Took the 257 Allen Mag out this morning for one final range test/bullet drop confirmation test before I head out in the morning to try to snipe a big mature pronghorn.

I have been playing with the 257 Allen Mag over the last few weeks getting her ready and have learned alot about the round as well as the limits of the rifle its chambered in as far as barrel weight and things like that.

The load I am using has the 156 gr ULD RBBT Wildcat Bullet ripping out at 3315 fps via 91.0 gr WC872. This is not a max load but its as hard as I want to push this very light weight barrel. Plus, I think this is plenty of velocity for a .800 BC bullet(Drop test determined).

Anyway, from several range testing trips I have determined that 700 yards is the max I will attempt a shot with this rifle and load combo. The load has the ballistic potential to hammer a goat at 2000 yards but this very light barrel at 30" simply is not stiff enough to offer the consistancy for anything much past 800 yards.

I can keep shots in the 8-10" range at 800 yards but just not tight enough for me to feel totally confident about taking a shot at this range. TO be honest I am looking to get a 600 yard shot to test this round out.

Anyway, this morning for the final bullet drop chart test which I finalized late this week and typed up and attached to the Weaver Tactical, I set out four water filled milk jugs at 445, 522, 567 and 612 yards.

I loaded the rifle with four rounds, three in the DM and one up the pipe. Started at the closest jug, ranged, looked up on the drop chart for the proper mil dot hold -0.7 mil and let a big 156 gr ULD fly down range. At the break of the trigger, a mist of water blew out from the back of the jug. The hit was a bit off dead center as it was about 1.5" low from center but perfectly centered horizontally.

Shot two, lined up on the 522 yard jug. Ranged it, looked up the hold which was -1.1 mil and sent another Wildcat down range. This one was a dead center hit, again the bullet seemed to impact the instant the trigger broke!

Jug three was then ranged at 567 yards. Looked up the drop hold, -1.4 mil and again the jug danced at the break of the trigger. This shot was a bit lower though. About 2" off center of the jug but again dead center horizontal.

I was thinking pretty highly of myself running 3 for 3 and now it was onto my last shot. I ranged the last jug at 612 yards and looked up the hold. -1.7 mils was what the printout stated. Lined her up and this time the big 156 landed about 1" under the jug in the loose soft dirt. it did however impact with enough force to lift the jug off the ground about a foot and roll it down the hill.

Even though I missed the last shot, I knew all four would have easily hammered any pronghorn at those ranges. In studying the hits I determined that +0.1 mil was needed to be added to the hold chart as the last two impacts were landing a bit lower then they should have been.

Anyway, I revised the drop/hold chart and taped her on the rifle so we are ready to roll at day break on a big buck from anywhere from the muzzle out to 700 yards.

If things go right I will be reporting about terminal performance of the big 156 gr ULD this time tomorrow.

Hope everyone out there has a successful and more importantly enjoyable big game season this fall and winter!!!

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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Unread 10-08-2005, 02:44 PM
Platinum Member
Join Date: Jan 2004
Location: Blackfoot, Idaho
Posts: 8,871
Re: Final range test before the pronghorn season opens in the morning.

Yea, blame it on the wife'e rifle! [img]/ubbthreads/images/graemlins/blush.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

Its raining and I have all of my preps done for Monday's hunt so I have some time on my hands.

Really appreicate posting those drop chart numbers. 1)makes a fella envious and to I like to mess w/numbers.

Hmmmm, lets compare drop charts[img]/ubbthreads/images/graemlins/confused.gif[/img]
Range Kirby's Roys
445 -0.7 -1.1
522 -1.1 -1.8
567 -1.4 -2.3
612 -1.7 -2.6

Ran a curve fit on your numbers and figured that you truncated instead of rounded up. Using my curve fit numbers and rounding up your 522 would be 1.2. 567 would be 1.5 and 612 would be 1.8.

I think that it is amazing that you could, from shooting calculate that 0.1 Mil adjustment. It says a lot for your craftsmanship and field experience.

Also my calcs indicate that you zero'd at very close to 100yds. Am I close?

Compare that to my zero of 290yds [img]/ubbthreads/images/graemlins/crazy.gif[/img] That's the way that I "cheat" to keep hold overs under 5 mils out to 820yds. (I'm not a clicker (come ups) but see myself going that way of a necessity). When I think about some super hooty 338 something its only to get to 5 Mils hold over @ 1K.

Another indication of the flatness of the 257AM is that the curve fit eq'n only had to be to the second order for a near perfect fit. My rifle takes a third order to get'er done. Even a flat shooting 270 warmed up takes a third order.

I'm betting the 222AM or whatever is y=ax+b which is the same equation as a lazer. [img]/ubbthreads/images/graemlins/laugh.gif[/img]

OBTW, the curve over Kirby's drop chart range is straight for all practical purpose. As they say in the dairy barn, udderly amazing.[img]/ubbthreads/images/graemlins/shocked.gif[/img] Velocity loss must be next to nothing.

What case is that thing gonna be based on, huh?

Sure hope you had the opportunity to achieve your goal on the goat hunt. (Bet he misses, Darn wife's rifle anyway! [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]) Just kiddin' fella. That's the kind of stuff I do [img]/ubbthreads/images/graemlins/crazy.gif[/img]

As for what I'm shooting its pretty much apples and coal stones for a comparison when compared to the 257 or any AM for that matter. See my signature line. [img]/ubbthreads/images/graemlins/blush.gif[/img] [img]/ubbthreads/images/graemlins/shocked.gif[/img]
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!
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Unread 10-08-2005, 03:39 PM
Join Date: Jun 2007
Location: Wyoming
Posts: 2,833
Re: Final range test before the pronghorn season opens in the morning....

Good Luck Bud!
One thing I always appreciate about you is you list the facts, even when you miss [img]/ubbthreads/images/graemlins/shocked.gif[/img]
We all do it but we don't much like to talk about it.
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Unread 10-08-2005, 06:07 PM
Join Date: Jun 2007
Location: North Idaho
Posts: 1,891
Re: Final range test before the pronghorn season opens in the morning....


Good luck on the goats hope you tag out at 600+.
Shawn Carlock

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Unread 10-08-2005, 07:07 PM
Join Date: Dec 2004
Location: El Reno, OK
Posts: 1,922
Re: Final range test before the pronghorn season opens in the morning....

Good luck Kirby. I have no doubt that you'll have some pics and a great story in a few days!!!
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Unread 10-08-2005, 09:19 PM
Platinum Member
Join Date: Jun 2005
Location: Yakima, Washington
Posts: 3,775
Re: Final range test before the pronghorn season opens in the morning.


Good luck and have fun. It looks like you've got everything you need but the big buck.

Will be looking forward to the upcoming report and pictures.

Hope they co-operate for you and don't show up at 150 yards, but if he does and he's a nice one, drop him. [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]
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