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270 Accubond Expansion Test

 
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Old 09-13-2008, 01:35 AM
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270 Accubond Expansion Test

I another thread it was reported that Nosler stated that at least 1800 FPS was necessary for Accubond expansion.

Hmmmm, a data point. I like data points. One can pretty much hang their hat on them.

If I could duplicate this stated performance, more or less, it would be a good test of this media I am developing.

I set up the container and added what I estimate would be sufficient moisture to the media.

The first shot impacted @ 1845 FPS. Terminal performance was dismal by some standards and impressive by others. Penetration included the full 24" of the media and the 1/2" plywood back end barrier. The bullet hit the back end of the plastic barrel but only dented it and fell to the bottom of the container.

This shot began tumbling upon entrance to the media, passing through the 14" plastic divider and the plywood end horziontally. The impact on the rear of the container was also horizontal.

Penetration was linear until the penetration of the rear board was completed when the bullet deflected about 3" in 9".

Deformation to this bullet was a loss of the front end leaving 133.2 grains, which in this case is not good.

A 200 FPS increase in impact velocity to 2050 FPS was tried to see if proper opening could be achieved. The bullet again tumbled and passed through the 14" divider cross ways. It hit the back board horizontally, only denting it. The bullet then bounced up hitting the top of the container landing on top of the media. I would suppose that if it were not for the container top being fastened properly the bullet may well have come back and thumped ol' Roy. (gonna get me a helmet......)

Penetration was the full 24" of media with a little energy left. With higher velocity a little more was broken off leaving 100.5 grains of the original 140.

These two similar performances appeared to reveal the need for a bit more moisture which was added.

Shot number three entered the media @ 2014 FPS.

Penetration path was a straight line from front to back. The penetration of the 14" barrier was large and round. The blunt front end of the bullet hit the plywood rear barrier leaving a visible dent. The bullet was found immediately at the front base of the rear back board. Bullet performance was near perfect. Mushroom diameter is 0.511".

Effective range of this shot is 1545 yds & 1565 FPE when launched at 3645 FPS. I wonder what kind of game it would be sufficient for, at that distance.

BTW, 1545 yards is a bit beyond my system's capability. The week part of the system being the driver.




This test would suggest that an impact velocity of at least 1800 FPS as reported stated by Nosler, at least the 270 140gr Accubond will more than likely open and upon entrance into an antelope or larger animal, maintain orientation, open properly, at least to 0.5" diameter, and penetrate a sufficient distance even at extraordinarily long distance (if started at something like 3600+ FPS;)) There ain't no dustin' these suckers even in a very tight twist 3-groove 30" barrel.

Using the 270 140 Accubond as the first recognized reliable expansion calibration point, it was easy to determine the amount of moisture to the media to replicate the Accubond's advertised performance.

My drop cart is developed and tested. I haven't developed the 140 NAB load to its best but quit when 200 yd grouped consistently printed less than 0.5 MOA. SDs are fairly good. Confirmation of down range drops will show if the NABs will shoot along with the 150 Ballistic tips which are super outstanding accuracy wise.

With the additional confidence in terminal performance of this particular accubond I otta be ready to start harvesting stuff......... It's about time!
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Old 09-13-2008, 08:39 AM
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Re: 270 Accubond Expansion Test

Thanks for all the info. I just recently worked up a load for my 25-06 using 110 AB's and I was very pleased with the accuracy.

Jeff
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Old 09-13-2008, 09:11 AM
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Re: 270 Accubond Expansion Test

Great post Roy. We all know that manufacturers claims can be off a "touch". Nice to see real world data.
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Old 09-13-2008, 10:10 AM
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Re: 270 Accubond Expansion Test

Great information Roy! Thanks
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Old 09-13-2008, 10:31 AM
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Re: 270 Accubond Expansion Test

Roy,

Great job on the test, good information. Thanks for all your efforts and post!

JD338
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Old 09-13-2008, 10:52 PM
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Re: 270 Accubond Expansion Test

Thanks for reporting the test & your efforts. I used a 270 last fall for Wy. Antelope & Mule
Deer & Ar. Whitetails. None of the shots were long by LRH standards, only out to 410 yards,
but 1 Whitetail was close & high shoulder shot. All showed great expansion & total penetration in every case. It is also the most accurate bullet I have fired in that rifle, doing 1/2" (3 shot) groups quite often, in fact the first group tried with this bullet was .187". With the BC it has it is a great 270Win allround choice in my view.
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Old 09-14-2008, 08:44 PM
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Re: 270 Accubond Expansion Test

Roy, great stuff as always. my only thought to your results would be the reason the bullets tumbled wasn't the lack of speed, but lack of rpm's. just as a bullet has to spin at a certain rpm to go straight through the air, it also has to spin at a certain rpm to go through "media". it takes more rpm's to stabilize going through media, than it does through air.

wasn't Kirby gonna build a gun for every caliber so we can test all bullets in regular twists at 1500 fps?
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