Home Forums Hunting & Shooting Hunting Rifles Rear core shift in partitions and A-Frames:

From some narrow point of view, some dude here on 24hourcampfire (about the equivalent of a teenage tiktok influencer) claimed that partitions have a tougher rear core than A-frames.

Out of ALL the A-frames I've recovered from Alaskan game and test media, the one bullet that has the most core shift is the 180 grain 30 caliber partition.

Here it is between 2 a-frames that were recovered from the offside hide of 2 bull moose (after breaking lots of dense bone). Be careful of biased bllsht and ask the person what type of business he's had with nosler where bias comes into play.

Secondly, different dude is looking for info on Barnes ttsx failures. This fkn guy is a MODERATOR on the nosler forum. Shady.

The A-Frame is my favorite bullet for anything big enough to matter.

I suspect that Nosler's "Crisis Pricing" has driven a lot of customers off to other brands.

Interesting results there Mainer. I've got some A Frames loaded, but haven't killed with them yet. Everything I've ever seen about their performance indicates they do indeed swell at the rear core, generally, in a way that partitions do not. A friend of mine killed a huge brown bear broadside at about 7 yards with a 300gr .375 A Frame. Seemed to work exceptionally!

The nearest thing to a "failure" I've had with partitions both involved 300gr .375s. The first was on a bull moose that slipped its core, but still managed to come to rest in the neck, up against the vertebrae after traveling through about four feet of animal on a quartering away shot as the bull ran off. The second "failure" was on a brown bear at 2 yards. I hit her as she was jumping up at me, right at the junction of the neck and chest. The bullet wrecked the top of the heart and lung piping before pulping about 8 inches of spine. It never exited, and I couldn't find any remains of it aside from a few fragments.

Anymore, I'd be happy to use either bullet and let pricing, availability, and individual rifle accuracy be my decision factors.

Front core gone is no real surprise, that's what a Partition was designed to do, smear away as it penetrates so as not to hinder penetration.

Rear core gone, that's not supposed to happen.

Don't know who the TikTok dude is, but it is easily proven that A-Frames feature softer rear cores than Partitions. A-Frames have used pure lead for both the front and rear cores since their inception in the mid-1980s--which is when I started using them.

The cores of Partitions are hardened with a little antimony--less in the front core than the rear, to encourage expansion. The rear cores vary a little, depending on the bullet, both to hold up under expansion and sometimes to enhance accuracy. The last I heard the .375 300s use 6% antimony rear cores.

This difference in hardness can also be easily demonstrated with a SAECO lead-bullet hardness tester, or any similar tool.

Many bullet companies tweak their bullets from time to time--including Swift, which tweaked the Scirocco after a few years. Nosler tweaked the heavier, larger caliber Partitions in the 1990s, moving the partition forward to retain more weight--but they didn't make any major announcement. The first I encountered were a pair of 300s from a .375 H&H used to kill a buffalo on 1998. Both shots were angling, and both bullets were recovered under hide on the far side. One retained 88% of its weight and the other 89%. In fact a few months later Phil Shoemaker stopped here for a visit, and of course we starting discussing bullets, so I hauled 'em out. He took one look and said, "That's perfect!"

Have used and seen used both A-Frames and Partitions in sizes up to 400-grain .416s, and both have worked well--except for some 300-grain 9.3 A-Frames, which apparently failed to bond. Between my wife and I we've taken around 400 big game animals with various bullets, and I've seen about as many more used by people I've guided, and hunting companions. Have yet to encounter a bullet that hasn't "failed" in one way or another when used often enough. Though of course many continue to evolve, such as Barnes Xs. Haven't seen a TTSX of any sort fail yet, and we started using them in 2007, including a major field-test I did in Africa on a cull hunt.

Don't know where the bottom cut-off line is for the Partitions that have the partition moved forward, but it might be the 225-grain .338. Have never recovered a .338 250-grain, but the one 225 recovered, from a huge bull muskox, retained 85% of its weight. Nosler designs those bullets so that even if they lose the front core the retained weight will be about 75%--which is what one of the two 286-grainers recovered retained. (The other 9.3 286 recovered, from a big bull moose in northern British Columbia, retained a little over 90%.) The most I've seen retained has been 95%, in a 400-grain .416 that entered a Botswana Cape buffalo at the rear of the left ribs and was found in the right shoulder. They average right around 90%.

PA, would yah look at that. Interesting stuff.

I recently read the craziest testimonial:

A hunter sent a swift a-frame into the fkn brain of an elephant. I was under the impression that a solid was preferred for this task, with all the bone a bullet has to travel through. The expanded bullet looks GREAT. If that ain't a serious test for a Swift A-frame, I don't know what the fk is:

"The second bullet looks essentially the same. However, fired at about 25 yards, it penetrated fully 10 inches into the skull of an elephant above the zygomatic arch. A softnose bullet is not meant for this task; it is slightly more compressed than the bullet from the buffalo, but it too mushroomed perfectly, even in solid bone, and did not fragment or fracture. Impressive performance.

~ Silvio Calabi"

https://www.swiftbullets.com/blogs/...me-bonded-semi-spitzer-416-rigby-bullets

Talked with Patrick at Swift. They disagree with the assertion that lead hardness has anything to do with a swift bullet maintaining its rear core, but rather, it's the rear jacket profile that matters most.

He chuckled and said the rear core could be made of hardened carbide steel, but the jacket profile matters most. They've done their homework on that rear jacket profile as well as jacket thickness.

Obviously looking at PA's heavy partition with a slipped core, this makes sense. Bias is a btch.

Yep, bias is a bitch.

Have seen some A-Frames completely disintegrate, four on the same animal, a water buffalo. The 5th one was recovered and retained 50% of its weight. While it did break the shoulder joint, it stopped against the ribs behind it. The bullet retained 50% of its weight, but was flattened into something resembling a thick quarter.

Do tend to prefer 200-grain A-Frames and Partitions in .300 magnums of any sort, having found their performance more reliable than 180s. And am willing to bet that I've seen far more of each used on game than you have.

As noted, any big game bullet can "fail."

Personally I don't like the 180gr Nosler partition. That's the favorite for most guys to suggest in 300 magnums etc. etc. Have had deer and elk catch them, while the 200gr partition always sails clear thru. You want a great partition, use the 200 instead. Unless you are shooting a 308 winchester. The 200 works like a champ even at 30-06 speeds. I've seen guys fret over not getting enough speed in an H&H with the 200 partition, but if it works like a mac truck plowing through a road block in a 30-06, it's going to be even better in a 300H&H, WSM, WM, wby mag etc. etc... Also, I thought everyone knew the A frame was a more stout bullet/design??? Been that way for years. Even though the partition has been the gold standard.

Another partition fallacy. A bullet shedding 30% of it's weight does nothing to help penetration. Piss poor expansion (like the 30 cal 220 partition) helps penetration though.

It makes about as much sense as marrying a prostitute from vegas.

You apparently didn't comprehend what I stated about heavier/larger caliber Partitions.

But penetration does not totally depend on retained weight--in fact far from it. The frontal area of the expanded bullet is at least as important. Have proven this many times in penetration tests with various bullets--and on game. And bonded bullets tend to expand wider than non-bonded bullets, whether Partitions or monolithics like Barnes TSXs.

The very first Partition I saw shot into a moose was a 150 from a .270 Winchester, which my wife used on a bull Shiras here in Montana in 1989. It was quartering away at 125 yards, and at the shot the bull took about a step and a half and folded up dead. The bullet entered the left ribs and was found in the right shoulder, several feet of penetration.

Just totaled the number of Partitions I've witnessed being used on big game, which ranged from 100-pound pronghorns and springbok to Cape buffalo, eland and moose weighing well over 1000 pounds. None of the 134 have "failed" to penetrate sufficiently to kill the animal promptly, even though several had to penetrate very heavy bone, or on angling shots, such as the moose described, or the Cape buffalo taken with a 400-grain Partition--which penetrated at least 7-8 feet on a very similar shot.

Yep, the heavier partitions retain better than 70%. Big fkn deal? You fail to comprehend physical evidence that even the heavy partitions slip rear cores as well.


I and Swift (and MANY others) disagreee with your biased garbage about about the hardness of the lead in the rear cores of their bullets being some sort of an issue.

I could honestly give a fk if you shot 100 pink balloons. My hunting experiences here in Alaska, always had reliable performance from the swift bullets.

What is your business relationship with nosler? Gushing fallacies all through the pages of their reloading manuals? What were you paid?

How much free product have you received from them? Be honest here, I don't really need your deflections or cocky, narcissistic bllsht. Youre not a nosler defense lawyer, though you sound like one.

Tell me some nam stories, instead......never too late to visit a recruiter station.

Have received plenty of "product" from not just Nosler but Swift and several other bullet companies.

Your initial post here contested my statement that the rear core of Nosler Partitions was harder than in Swift A-Frames. If the Swift people disagree, that can easily be proven untrue, for the reasons I stated earlier. I didn't say it was an issue, but it does tend to result in expanded rear ends of A-Frames, which along with the wider expansion of the front core does tend to reduce penetration compared to some other premium bullets. On the other hand, A-Frames tend to make bigger holes in big game for the same reason, which definitely helps kill stuff.)

You have not presented any evidence that heavier, larger Partitions "slip" rear cores. The only incident you've presented is one 180-grain .30 from a .300 Winchester Magnum.

My job is to evaluate all sorts of stuff, including hunting bullets. Which is why I've not only hunted with plenty of different brands, but tested them in various kinds of media. The bullet companies I've also received plenty of "free product" from have included Barnes, Berger, Cutting Edge, Hornady, Nosler, Norma, Lapua, Remington, Sierra, Speer, Swift, and Winchester.

Have also had many of those companies (often in partnership with ammunition, optics and firearms companies) take me on hunting trips for animals from prairie dogs and coyotes to Alaskan moose and Cape buffalo--usually with several other people. I've often been able to accompany and observe their field results as well.

As an example, have been hosted on hunting trips around North America and sometimes other continents by Benelli, Beretta, Berger, Bushnell, Hodgdon, Hornady, Kimber, Leica, Leupold, Nosler, Remington, Ruger, Sako, Swarovski, Tasco, Vortex, Weatherby and Winchester--and some others I don't recall right now. Also, more than one magazine I've worked for paid for all or part of the expenses for various hunts, including a mule deer hunt in Sonora, a 10-day horse-pack hunt in northern British Columbia, and a Cape buffalo/plains game safari in Botswana.

Have also been invited by outfitters/booking agents on various trips, who provided a "free" hunt if I paid for my travel and hunting licenses. But have also spent plenty of my own money on hunts from Alaska to Africa to Europe. (This included the buffalo hunt where I used the 300-grain .375 Partitions mentioned in my earlier post.)

Quite often "hosted" trips have involved try-outs of new products, some of which did not work out--which is one reason they often invite experienced hunting writers, who can provide valuable feed-back.

More than one of those companies told me they invited me because they'd found readers trusted me to provide an objective opinion, partly because of the tests I often perform after the trips, which have appeared in many magazines and my books. This was also often true of other writers invited on the same trips.

More deflections. You've been PAID by nosler, plain and simple.

Who said anything about a 300 mag? I sure didn't. That 180 grain bullet came from a 308 winchester.

Did you miss the photo PA provided? Do I have to spell it out? That bullet with the slipped rear core, was a .375 partition. Spit the fkn rear core right out.

Dance around the subject all you want. The hardness of the lead in the rear core of a Partition is no advantage over the A-frame, it doesn't mean sht. It's the jacket profile that matters.

It's like I'm talking to a dyslexic politician, unbelievable.

You do realize what the bullet(s) are showing perfectly, no?

That is obvious evidence of tumbling... not good for tracking straight...

mainer,

Sorry I missed some of the details you mentioned. I'd had a long day and was very tired.

My main point, as stated in one of the posts, is that any big game bullet can fail if enough get used on various animals--and I've seen it happen a wide variety, including A-Frames. But I wouldn't have so many A-Frames loaded up and ready to go if it wasn't a very rare occurrence.

Gents, regarding the slipped core with my .375: As I said in my initial post, it was hardly a failure since the bullet penetrated over four feet of animal before coming to rest against the spine so pictured. Again, if that's a "failure" may I be so lucky to have such "miserable" performance for the rest of my days. Correct Art, It tumbled at the end of its travel as it came to rest, as evidenced by the orientation of the jacket, but drove straight before that (I've got a 286gr 9.3 that did the same thing as it snagged on the hide nearly exiting the off side of another bear). Of the other two bullets I shot into that moose, one sailed clean through and the other was recovered looking like sample from a gel test advertisement. In my pile of recovered bullets, besides the slipped core sample I've got 7 other recovered 300 gr .375s that I shot into mountain goats and brown bears at ranges from 12 to 250 yards, and they all look advertisement worthy and retained 68-70 percent of their weight. And that's a small sample of the ones I've used on a pile of brown bears, most sail on through. And no deer has ever or will likely ever catch one. That's just my experience. I like the Nosler: It's hard not to like something you owe your life to. But had I been using A-Frames this whole time I'd probably be just as happy as I am now.

Mainer, let's not totally kook out here, you're sorta being a dick. If Nosler wants to say that the hardness of their rear cores affects performance and Swift wants to say it's jacket profile that does it, they're both allowed to say and believe that. If Muledeer reports what Nosler told him about it, then I reckon that's what they said. There's also no reason to think you're misreporting what the guy at Swift said. You'll have your work cut out for you if you're gonna try to impugn the integrity of Barsness. It's pretty obvious he's got the experience to have a great amount of raw data, along with the wit and journalistic integrity to glean the truth and tell people how it is. He was also pretty frank a post or two ago about how he's been compensated by companies. None of that is unusual in gunwriter world. What is unusual is that he's happily told us the good and bad about what he's seen from all that stuff. If he wasn't being fair and accurate you wouldn't see so many companies on that list of provided stuff. Michael, you've got a great body of real-world experience and the integrity to tell it how it is based on that experience, but slow up on the insults, you're getting mud on yourself flinging it all over.

That is surprising. Why is that?

I assumed that, for example, with the same bullet diameter, weight, and velocity, a NBT would expand more than an AB. Is that not correct?

It's not, as a general rule. The frontal jacket of Partitions tends to fold back alongside the rear jacket/core as it expands, while the frontal jacket of AccuBonds is "supported" by the bonded core. Thus expanded AccuBonds tend to resemble an actual mushroom, wider than the "laid-back" jacket of expanded Partitions.

That said, Accubonds do penetrate very much like Partitions--they just don't pop through the hide on the far side as often. But even then there are exceptions. One I've used a lot, both in North America and Africa, is the 250-grain AccuBond from the 9.3x62--and like Partitions the heavier, larger diameter AccuBonds are designed to retain a higher percentage of weight. The only one I've recovered was from a follow-up shot on a 7-1/2-foot Alaskan grizzly, as it ran angling away after taking the first shot through both lungs. That bullet landed in the middle of the right ribs and was found under the hide over the left side of the bear's neck, retaining a little over 80% of its weight.

pabucktail,

Thanks for your comments--but will make another comment here that also peripherally involves this discussion:

In the last decade Eileen and I have been using more and more monolithics, mostly Barnes TTSXs and LRXs but several others as well, including Cutting Edge Raptors, Hornady GMXs and Nosler E-Tips. We've also used more lead-cored bullets with solid shanks such as the various Trophy Bondeds, especially Federal's plastic-tipped version, or the late lamented North Fork. All of these bypass the rare problems concerning rear cores in either A-Frames or Partitions--and in the past five years our use of monolithics had increased to over 75% of our big game hunting. (It's been nine years since I killed a big game animal with a Partition, and 10 since Eileen used one, though am sure we will again.)

Might also comment that the Nosler folks also believe, like Swift, that jacket geometry plays an enormous role in Partition performance.

John