Nosler Partition - Efficacy and Defects

[rookhawk]

I was gearing up for Africa and found these old mementos from last summer to share with you. Other people were asking about some of this info but I felt bringing it up in their threads would become a distraction from the conversation.

I'm a 7x57mm lover, a heavy bullet for caliber lover, and an impact at 1900-2400fps for proper controlled expansion and energy transfer fan. Thus, I've had very good luck with Nosler Partition 175gr projectiles.

The picture is of a retrieved bullet from an Ontario black bear and a Greater Kudu from last June and August. As you'll note, they worked very well. I also had no defects, bolt-of-lighting efficacy on Warthog, 9 impala, 2 baboons, steinbok, and a few other animals in the past 12 months.

I share this info because I had to find out for myself why I've had such great luck and others have had such bad luck with Partitions over the years. (jacket separation, total franging, etc.) I don't believe it is luck and I don't believe the complainers are liars so I did a lot of research and some interviews on this topic. After speaking with some of the top commercial/custom loaders in the business, this is the working theory:

Bullets less than 150-160 grains and in diameters less than 7mm / .284 seem to be group A that has occasional problems with partitions.

Bullets of 7mm and greater fired from guns in the 2600-3200 fps range with high twist rates seem to be the group B that has problems.

The experts believe that the centrifugal force of the Partition at high speeds and high rotations is dislodging the jacket from the core during firing OR during initial impact resulting in these problems. They believe the .22-25 caliber partitions have too little core area to adhere the jacket too properly and the bonding fails.

For what it's worth, I'd not hesitate to use partitions in 7x57, 30-06, 35 whelen and the other calibers that push bullets at that ideal 1900-2400 fps impact velocity. The stories of bullet malfunctions appear to not apply to these calibers/velocities.

 

[Clayton]

Interesting. I've wondered about mine over the years, I've never recovered a partition and never had to put more than one into an animal. Thanks for sharing the info.

 

[spike.t]

i like them.

 

[Witold Krzyżanowski]

Very interesting.
Witold

 

[JGRaider]

I'm not very scientific, and much prefer actual epxerience over numbers. I've taken well over 100 big game animals with 7mm 140,150,160 partitions running from 2800-3050 fps. I've never experienced a failure of any sort, rarely recover one, and if there's one bullet I would consider to work as designed every single time it would be the Nosler partition. Other bullet manufacturers have been trying to emulate, or play catch up for the past 60 years.

 

[sheephunterab]

Let's not forget that the Partition in 1946 technology. It shouldn't come as a big surprise that jacket separation and excessive fragmentation happens with very high velocity hits. The bulk of these high velocity chamberings didn't exist in 1946. The bullet was designed for low-medium velocity hits. Each bullet has their own performance envelope and many of the new magnum chamberings fall outside that envelope for the Partition. Use a bullet for what it was designed and expect good performance.....stray outside that performance envelope and expect less than ideal performance.

 

[JGRaider]

Lot's of hunters call a partition a "failure" when the front end sheds it's weight and fragments. They don't realize this performance is exactly how it was designed. Weight retention of 60'ish % is normal, very deadly, and exactly the way they have performed for me when I've been able to catch a 160gr 7mm bullet.

 

[Big5]

I must agree with JGRaider.

I've hunted a wide variety of game species with Nosler Partitions since the early 70's and haven't experienced a single failure. That's why I've continued using them for so many years in my .270 Wby, .300 Wby and .340 Wby . . . all considered to be reasonably high velocity chamberings.

To each his own and good hunting to you all.

 

[Velo Dog]

Hi JGRaider,

I am +1 with you on what the NP bullet was designed to do, specifically.
In other words, it was designed to shed the front end at relatively high velocity impacts, leaving a cylindrical shaped projectile, with sharply jagged face, to then "drill" it's way through the target, and yet at lower velocity impacts, the front end often stays attached, but easily deforms, leaving a more or less classic "mushroom" shaped projectile to do the work.

The sort of similar looking Swift A-Frame departs from that design a bit by being made with the front core tightly bonded to the jacket, so that it only "mushrooms", even at very high velocity.
In the times that John Nosler was an avid moose hunter, common bullets were very soft, compared to current "Premium" bullets.
The quite fragile Winchester "Silver-Tip" was one of, if not the most commonly available bullet in factory live ammunition, for the .300 H&H.
My understanding is that, after a serious bullet failure, John Nosler conjured up his partition design to give his ammunition better penetration while hunting Canadian moose, with his Winchester "Model-70 Westerner", in .300 H&H / 180 grain.

If that is so, then the original concept was designed around a 180 grain .30 bullet, leaving the muzzle of a 26" barrel at about 2850 fps to 2900 fps, more or less (not exactly low velocity IMO).
Just like yourself, I have enjoyed perfect success from the Nosler Partition on hooved game (including while using the .300 H&H / 180 grain in Namibia).
Who cares if the front part flies apart, as long as the rest of it bores on through the vitals.

All that being said, the NP can completely fly apart, from point to base, (like any dreaded "cup & core" bullet can) if driven fast enough against a hard target (partial or total combination of: dried mud, thick leather, thick muscle, thick tendons, heavy bones).
But since I don't care to use small / fast bullets for large / heavy animals, it does not adversely affect me.
However, I do very much like the Nosler Partition for deer/antelope hunting in more open country hunting conditions, where shots tend to occasionally go beyond 200 yards, or perhaps even beyond 300 yards on the odd occasion.
Although the NP in .416 / 400 grain or .458 / 500 grain might or might not be just the ticket on African buffalo, it is not the soft that I would choose for buffalo, in those two excellent calibers or, any caliber for that matter.
The much tougher A-Frame is commonly available in many buffalo calibers, and it would be my preference for buffalo (as always, provided it regulated well in whatever rifle I planned to use).
But for typical "plains game" (and most world-wide hooved game species), I believe the NP to be one of the very best choices.

Cheers,
Velo Dog.

 

[MarkCZ]

Just got back from Namibia. I shot Baboon, Warthog, Red Hartebeest, Oryx, and Springbok and all dropped to the spot almost, except for an Oryx that I hit a bit high and had to be followed up. I used 165 grn Nosler Partitions in my 30-06. I cannot tell you how much I rate this bullet. 3 trips now to the "Dark continent" and I would not go with out the "partition".
MarkCZ.

 

[PHOENIX PHIL]

Lot's of hunters call a partition a "failure" when the front end sheds it's weight and fragments. They don't realize this performance is exactly how it was designed. Weight retention of 60'ish % is normal, very deadly, and exactly the way they have performed for me when I've been able to catch a 160gr 7mm bullet.

I must totally agree too. I've recovered only one NP. It was a 160gr 7mm fired out of my 7mm Rem Mag at my Idaho Shiras moose almost 15 years ago. It was found under the skin on the offside, moose went about 10 feet and dropped dead. It's after use weight was right at 80gr so a bit below the 60% average. But this is exactly how it was designed to work and what John Nosler was after.

Personally I think that the Swift A-Frames which are simply a bonded version of the NP and the North Fork Bonded Cores are even better bullets particularly on big DG. But in most situations I would not hesistate to use one. I would like to see Nosler develop a true bonded version of the bullet giving the option of essentially another A-Frame.

 

[Sako AV]

Never had a Partition fail to penetrate or put an animal down quickly if I did my part! Too much emphasis is put on what a bullet looks like after it is retrieved from a game animal. Obviously, if the bullet can be retrieved it did not fail.

 

[sheephunterab]

Actually I'd say what Nosler was after was compensating for the poor cup and core performance of the time with the solid partition toward the rear of the bullet. One needs to remember this was at a time when bonded bullets hadn't even been imagined. It truly was innovative for the time but with more advanced metallurgical processes it's become easier to retain weight at the front of the bullet, negating the need for a solid partition in front of the rear of the bullet. This has unquestionably resulted in more accurate bullets. If there's been one constant knock against Partitions it's accuracy.

 

[Divernhunter]

I have used partition bullets on a lot of game and they never "failed". Most of the time I never recovered the bullet but I always recovered the animal and a short trailing job was the most I had to do. If I recover a bullet(from a dead animal) or just collet a dead animal then in reality the bullet did not fail. It may not look like some picture someone thinks it should look like BUT it did NOT fail.
I have heard the accuracy thing about Partitions/A-Frames but I have been able to get max speed with groups of 3-5 shot from my hunting rifles using only a front sandbag that are basically all touching. That is accurate enough for me and that is with 257R/25-06/257W/6.5X55/264win mag/7mmRem mag/7mm-08/308win/30-06/300win mag and 338win mag rifles.

The A-Frame is like the Partition except it has a pure copper jacket and a bonded core. To be honest I now prefer the A-Frame for my mag cartridges and my 25-06. I also used the A-Frames in Africa for my daughters 257R with 100% one shot no tracking kills. Same with my 338win mag. I do think a Nosler Partition would also have worked but why not use something one step up the ladder and also a proven performer.

Yes the Nosler bullet was designed for the front part to wipe away and to actually loos 50% of its weight. It also was designed before we had so many super mag rifles. It worked then and it still works. Hunters need to remember to choose the bullet for what and where they are hunting. Some of the super bullets are actually too hard and do not expand/preform well at lower speeds and lighter skinned/body animals. Sometimes a lesser bullet is really better. That is one thing I like about the Nosler bullet with the front quickly expanding and wiping away while the rear section keep driving on. It works for small light bodied animals and larger ones also in almost any cartridge.

My 2 Cents

 

[colorado]

Let's not forget that the Partition in 1946 technology. It shouldn't come as a big surprise that jacket separation and excessive fragmentation happens with very high velocity hits. The bulk of these high velocity chamberings didn't exist in 1946. The bullet was designed for low-medium velocity hits. Each bullet has their own performance envelope and many of the new magnum chamberings fall outside that envelope for the Partition. Use a bullet for what it was designed and expect good performance.....stray outside that performance envelope and expect less than ideal performance.

Actually the Partition was designed to do two things, hold together at relatively high velocity (think 130g bullet at 3000 fps out of a 270 Win) and still expand reliably out to 500 yards on North American big game (think deer, elk, black bear and grizzly). The front section would disintegrate and cause massive damage at close range while the rear section would continue to penetrate, yet it would still reliably expand at under 2000 fps at 500 yards. Very few bullets today will perform at both high velocity and low. A damn good design for it's time. The 150g Partition is still our go to bullet in our 270 Wins

 

[sheephunterab]

I seriously doubt there was much thought given to 500 yard performance in 1946 but no question it would work at those impact velocities . Accuracy, however, is the limiting factor for it being a contender in the long-range arena. I'm not sure 40-50% weight loss is considered holding together but the rear section does maintain it's weight. It was indeed a damn good design for the time though and remains an effective killer.

 

[MarkCZ]

Actually I'd say what Nosler was after was compensating for the poor cup and core performance of the time with the solid partition toward the rear of the bullet. One needs to remember this was at a time when bonded bullets hadn't even been imagined. It truly was innovative for the time but with more advanced metallurgical processes it's become easier to retain weight at the front of the bullet, negating the need for a solid partition in front of the rear of the bullet. This has unquestionably resulted in more accurate bullets. If there's been one constant knock against Partitions it's accuracy.

I would agree to this .The Partitions group in my gun about one and half inches at 100 yrds. Sierra Gamekings group much tighter usually half inch. I can cope with inch and half as in hunting conditions it really dose not matter. The quality of the bullet is what counts on African game. I would use the Sierra gamekings on any U.K. game.
MarkCZ

 

[colorado]

I think the North Fork bonded softs are about as good as one can get for an expanding bullet these days. The Swift A-Frames are good too. Neither has a great ballistic coefficient, but then again I tend to shoot up close and personal these days so it doesn't matter much.

 

[Mekaniks]

Nothing wrong with NP bullets and I think they work great in any hunting caliber traveling between 2000fps - 3000fp. I have taken a Kodiak Brown bear and several deer with handloaded 210g Partitions from a .338 Federal leaving the barrel at about 2500fps. I am confident enough with them that I am going to take the same to SA plains game hunting in September.

 

[colorado]

My 270 using 150g Partitions at 3000 fps have accounted for dozens of elk, seven black bears, and more deer than I can remember. Like I said, our goto bullet for our 270 Win. We like the A-Frames in our 375s, 416 and 500 Jeffery though the TSX seems to work well in the 500 as well.