.308 Winchester 125 grain Accubond - Test

[andrewctillman]

Test results are in.



Muzzle velocity, 3,160 fps.

Velocity at target, about 2,985 fps.



Target:

two 5 gallon nylon Home depot buckets filled with water at 75 yards. (90% correlation to critters for frontal area and 95% for retained weight). 11 inches deep x 15 inches high. Center hit.



Expansion, uniform .604 average diameter. (.573 x .608 x .627 x .610).



Weight retention, 80.2 grains, 64%.



Height of bullet, 0.324 inches.

Penetration, 1 1/2 buckets or 16 inches. (No sign of denting rear of second bucket). And no noticable damage to the second bucket. (Lid remained tightly on).



Likely over pressure, .270 winchester class on first bucket which is unusual for a .308. It split the front and rear of the bucket open which is similar to a 130 grain 270 winchester, and a good indication of a bang flop on a heart shot. Almost completely tore it in two which is very unusual for a .308. (Usually requires magnum ctg at point blank range).



Observation about this bullet. I was plesantly surprised that it maintained its frontal area without the mushroom being swaged down parallel to the bearing surface of the bullet. The jacket was thick enough to support the expanded mushroom. About 1/4 inch of bearing surface left unexpanded above the boat tail solid base. Bright shiny lead core, probably has alot of tin in it? Lead fragments fused onto base of bullet and underneath mushroom suggests the bullet turned over 180 degrees and traveled base forward after penetrating the second bucket. Surprising since it is so short and over stabilized from 1-10 twist and with high MV. Generally not a good thing for a bullets integrity since the metal work hardens when it expands and can break off easily base forward. (This is how long for caliber Barnes X bullets loose their X petals).

7.62 NATO Mk 319 ammo (130 grain solid base fragmenting HP) has MV of 2950 fps and compltely tears first bucket in two at point blank range, severely damages second bucket, and recovered in third! 51 grains retained weight but only .324 diameter copper base remaining. Nosler not likely to duplicate MK319 as barrier blind load but far better than an unbonded bullet of this weight. Pictured 556 Mk318 on left and 762 Mk319 on right. (The Nosler 64 grain bonded solid base at 556 velocities equals or exceeds performance of the Mk318 on most targets).



The similarity of MK319 and 125 AB on first bucket demonstrates that the large expanded FA of a good bonded bullet at high velocity can nearly equal over pressure and temorary cavity of the most extreme fragmenting bullet.

Percentage of weight retention of the 125 grain AB is actually similar to a 180 grain Woodleigh out of a 30-06 at 400 fps less velocity! I like it.

 

[DrMike]

Very informative. Your tests should give those use the 125 grain AB in their 30 calibre rifles great confidence. Thanks for posting.

 

[andrewctillman]

On closer examination of the bullet I see why it lost 35% weight.

What appears to be lead adhered to mushroom is either a very thin coating of lead or just solder. The lump you see in the center of the bullet is lead. Everything else you see in the surface area of the bullet is not. I dont know if another 25 - 30 grains of retained weight would have increased penetration or not. That is greatly determined by FA. I think the lead alloy is quite brittle and flakes off though. I am used to Bitterroot, North Fork, original TBBC, Kodiak, and to a lesser extent Swift, and they all appear to be pure lead core which is very ductile. Woodleigh, TBBC by Speer and this Acubond appear to have more tin in the lead. But it will be dandy for small game it is intended for.

 

[CatskillCrawler]

The AB was designed to duplicate the 65% weight retention of the Partition using a bonding process instead of the more expensive Partition design. It should expand violently early after penetration and then retain enough mass to penetrate deep.

From my experience, it does this superbly. Your results seem to validate the design objective. That 125gr pill seems to be the little caboose that could!!

 

[Guy Miner]

Yup. It acts about like a Partition, which was the intent.

 

[SJB358]

Man, that bullet looks really good. Impressive penetration as well.

 

[andrewctillman]

Catskill and Guy,

Do I understand you correctly? The front of the AB is not bonded but rear is? So it fragments 35% like a PT, but it stops expansion/fragmentation with a bonded core instead of a Partition?

PT lead and jacket fragments can be quite large and tear up alot of meat and organs as we all know. The AB I tested had miniscule lead fragments that were more like sand than what you get from a PT, cup and draw bullet, or the 762 MK319.

I am pretty sure that neither Woodleigh, Swift Scirocco, or TB by Speer wanted to end up w 70% weight retention, they just did based on their choice of materials.

Still way better than a conventional bullet but a long, long way from the original bonded bullet the Bitterroot, or the best currently made for FA and weight retention and able to handle HV with low SD, the North Fork, which equaled or exceeded the original TBBC.

Obviously I want my bonded bullets to retain more like 90% which the better ones can do. (See my test of premium 458's).

I loaded up 50 more of the 125 AB's though, so Nosler got my money.

If I were hunting plains game or elk w a .308 win up to .300 magnum I would certainly use a North Fork rather than any of the bullets in the 70% class.

Just my 2 cents.

 

[Ridgerunner665]

The whole core of the AccuBond bullet is bonded, that is to say the outer perimeter of the core is bonded to the jacket....but its an alloy that "peels away" as it expands...the bonding holds the core to the jacket, but the core will still come apart and peel off due to the forces of impact.

By design...within its velocity range...the AccuBond loses ~30% of its weight during expansion...the other bullets (Swift, etc.) likely did design their bullets to do the same...though I don't know that for a fact.

Bonding doesn't mean the core won't come apart (fragment)...bonding only means the core won't separate from the jacket completely.

At least thats always been my understanding/observation of it...the alloy of the core dictates how much fragmentation occurs within a particular velocity range...bonding only holds the core inside the jacket, it doesn't hold the core itself together.

 

[nvbroncrider]

Andy look at the tests Scotty and I did on the 6-90AB I sent it into jugs at 3714 he got them at 3kish and then again somewhat slower. They are just really impressive. Weight retention depends on a few factors from what I've seen. First is design second is expansion and last is velocity. There was a really neat article on premium bullets in a magazine done and what's awesome is the consistency of these bullets. They are unreal. You also have to account for penetration and expansion which directly correlate to each other. I'd rather lose some weight and have expansion and good energy transfer with a good blood trail than a bullet that punches through retains all of its weight and leaves no blood trail or one that expands rapidly and disperses all of its energy quickly and leaves no blood trail. Just my 2 cents.

 

[andrewctillman]

Thanks Guys,

Guess I am spoiled.

Ive seen antelope, deer and elk shot with 140 grain Bitterroot at 3400 fps on some pretty tough shots, close range and bone, and they retain 90 - 95%.

And they are the benchmark for expansion.

180 grain Bitterroot in custom 300 weatherby (0.3085 bore) makes over 3300 fps with fire formed winchester brass and case full of 4831. Expands flat as a pancake on elk and bison and still retains 90%.

faster you drive them more they penetrate.

North Fork nearly as good. 400 grain .458 Point Blank on Cape Buffalo and 2750 fps. Same thing. 90-95% weight retention with .82 caliber expansion.

Pure lead cores and pure copper jackets, not tin and gilding metal.

Makes a difference.

AB's were accurate and not at all fussy about powder or OCL.

Thanks for 6 mm link.

 

[andrewctillman]

Another range day.

1/2 x 1/2 inch center to center five shots, twice. Just one big hole. About 1 3/4 inch high from my 175 grain Black Hills ammo. Very convenient.

Over 3,200 fps now with latest powder throws. 2.81 OCL still works in AI magazines. Rifle seems to like Winchester once fired brass. Trimed to length is all. No run out or neck turning. Amazing accuracy.

Previous dispersion in new brass with neck run through expander die was 3/4 x 3/4 inch.

More consistent neck tension I imagine with once fired brass, a bit more powder, and a bit longer OCL. Wow!

 

[Guy Miner]

Some of us don't believe that more weight retention is better... I like to see some bullet fragments coming off and destroying the lungs.

Even the 260 gr Accubonds I've tested, and subsequently used on bears have shed quite a bit of weight. The very sturdy base though remains completely intact, driving forward - just like a Partition.

I just think of the AccuBond bullets as Nosler's answer to those folks who keep asking for a poly tipped Partition. The AccuBond performs just like that.

Regards, Guy

 

[andrewctillman]

Guy,

Interesting observation about the poly tipped Partition. I can see the AB as a substitute for that.

The Bitterroots, original TBBC and North Forks also destroy heart and lungs but do so with expanded frontal area and large permanant cavity they create. I have always tried to hit something hard when using them to create bone splinters.

The 375 caliber Bitterrots would cause instant death on bison w a heart shot. I believe a 250 grain at 3100 or 275 at 2975 fps (improved case) caused brain death. 75 caliber bullet (expanded) at that velocity is just a killer.

I have seen bison just stand there with most of its heart gone using a .300 until its brain ran out of oxygen, and am sure many here have seen deer run 30 yards with heart gone from HV 30 caliber. It normally takes an animal 20-30 seconds to run out of 02. But the large expanded FA of the best bonded bullets kill instantly. No fragmentation required.

When I killed my huge Kudu in 2005 with a 450 grain NF at 2550 fps, my PH was sure I hit its spine the way it piled up but it was just effect of an .82 caliber (expanded) bonded bullet at high velocity (for a .458).

I would have thought a 260 AB was light for bears but guess you proved otherwise. I am betting it was accurate too!

 

[SJB358]

I have read a bunch about the Bitterroot Bonded Bullets from the older writing of Bob Hagel and others but haven't ever fired the first one. I know the folks that have them are holding onto what they have dearly. I have seen the same as Guy, with the AB being a sort of poly tipped PT. I understand some bullets may hold onto more weight or expand larger or penetrate a little deeper, but the plain old Partition still seems to do really well. I have some 338 225's Northforks to try and some 358 270 Northforks. Actually looking forward to seeing both of those two in action. Everything I have heard, seen (alot from you AT) makes them look like great bullets.

Keep the bullet testing going. This is great stuff. Hopefully as Fall gets closer we can see and hear of some more animals being taken with these different bullets.

Andrew, have you worked with the 338 Win Mag and the Northforks at all? I wrote them about seating depth's for their bullets and they said to start at .050" off and work from there. What has your experience been with them? I know every rifle is different and such, just wondering how they have worked for you?

 

[andrewctillman]

SJB,

I have most experience with the .450 Dakota and in that rifle they did best seated long (even by 450 standards). They were not at all difficult to work with. Only powder that thy did not like was IMR 4350, and for some reason it fouled the barrel terribly. Yet 4350 worked great in my 375 improved. They are longer than a Bitterroot and I lost about 100 fps using them. (2700 fps instead of 2800 fps with the 300 grain). Anyone else wold consider that fast from a 375 improved with 22 inch barrel.

I have not tried them in 338, but did in pre64 7mm Remington mag w 26 inch stainless barrel. I was using RL25 and it acted like a 160 AB. Go figure.

They are not fussy about OCL. I would just follw their advice which is good advice for any solid base (TBBC style) or monometal bullet and begin 5% below a conventional product load density. The 225 should be a winner and would be my first choice in a 338.

I began using the Bitterroot in 1979 or 1980. Previously I had used partitions in 257 weatherby and 300 weatherby. Totally different wounding mechanism as Guy has pointed out. FA vs fragmentation. Ruins less meat than a PT. (I threw away a 300 pound deers front shoulder once w a heart shot using the 180 PT in my dads 300 weatherby).

Bill Steigers and I visited Nosler in 1988 about making bonded bullets but that was too controversial of a move for them back then. What made the Bitterroot such a good bullet besides pure lead and copper was the way Bill swaged the interior dimensions of the jacket into a deep V shape. The jacket near the heel could be 0.064 thick yet it was very thin at the meplat. The bullet expanded rapidly and then was slowed down and supported by the thick and ductile (annealed) pure copper jacket.

Bill taught me alot about bullet performnce and was a mentor who also taught me alot about life and how to be a man. He was (is) a real pioneer and a perfectionist. Former NRA board member. Mike Brady who founded NF wrote the best and most accurate article to date about bonded bullets for Dakotas magazine. Dont know if it is available on NF website but it should be. No "payola" journalism there as you may have seen from other authors. I helped get Mike and Bill together for an interview.

the NF's work so well because they start out with hard copper alloy (it is available in hard or half hard) and by the time it is annealed (bonded) it is just right. I got to know Mike as I was conducting my test of 458 bullets and like Bill Steigers, he was a perfectionist who loved to experiment and test his products. Bill would consider them a medium expansion bullet since they are a TBBC pattern which he credits PO Ackley with inventing. Bill tried it in bonded form and abandoned them (too long). All of this long before TBBC and Swift. Great article if you can find it.

You wont be sorry you tried the NF.

No other bullet made today can stand up to such HV with low SD.

 

[SJB358]

Great info AT. Really like hearing about bullets and how they work. Keep passing the information. I'm listening ears and eyes wide open.