I'm not new to the mono copper concept, but after suffering poor performance (akin to penciling) with the original Barnes bullets, I was reluctant to get back on that horse.
In the 20 or so years since, I have come to learn that not all bullets are equal. Even if they are in the same 'line'. For example, a 30cal 165 gr Accubond and a 7mm 160gr Accubond - very similar bullets, very different performance in my hands. At moderate impact velocity (~2500fps), the 30cal 165er expands well on deer sized game, but, as evidenced by permanent wound channels, the 7mm 160gr does not.
Nosler partitions are another example. I have a fair bit of experience with the 30cal offerings, but take the 180gr and the 200gr for instance. Given similar target resistance and similar impact velocities, those two perform quite differently. I have caught several 180's on the offside of a moose. Never caught a 200, and have sent them lengthwise through an elk on 2 occasions.
When it comes to the 'type' of bullet, I have learned that generalizations CAN be made, but they don't always hold true in the real world.
Nathan Foster gets into the individual performance of specific bullets a bit on his site;
ballisticstudies.net
I know he has been mentioned, but the reference is worth repeating because it's a quality resource, in my opinion.
So... What has this got to do with MONO's?
I don't think it's fair, for instance, to compare Hammers with Barnes. I have used both, and while yes, both are made of copper, the similarities end there.
Where internal ballistics are concerned, Barnes build more pressure than conventional bullets - it's tough to get the same velocity with Barnes as one would with a conventional bullets of the same weight.
Hammers are the opposite. Due to the PDR drive bands, the hammers experience less resistance when engaging the lands and can be pushed to higher velocities with the same peak pressure.
When it comes to terminal performance, above 1800fps, hammers behave more like a Nosler partition than 'mono'.
You will notice Hammers always shed their petals. Barnes not so much.
The 'shedding petal' thing seems to be unique (among copper bullets) to the Hammers. This leads us to 'cavitation' which is a subset of Hydraulic shock.
I understand great pains were taken engineering the petals to shear off leaving the shank as flat as possible.
Based in part on the research here;
^^^ Link
(Another fantastic resource)
My understanding is that careful materials selection, by Hammer, and attention to cooling during machining are prerequisite.
I don't know the specifics, but copper is susceptible to work hardening during drawing and machining.To keep copper soft, it needs to be slow-drawn, annealed and have careful attention to cooling during the machining phase.
Hammer has their materials selection and process dialed in, and as a result, their products are very different from 'the other guys'.
I drank the Hammer kool-aid for the first time last year - only a handful of ungulates taken thus far, but I like what I see.
~3000fps impact velocity, lungs completely liquified
View attachment 309715
Yet very little meat damage. Exit wound butterfly
View attachment 309713
Here are some mule deer lungs from a longer shot. Impact velocity ~2500fps.
View attachment 309714
Not liquified, but severely torn up. Good terminal performance across a wide velocity window.
'pill' was .284 140gr Absolute Hammer
Anyhow, this post is getting long, my main point was that generalizations are dangerous and we shouldn't lump all copper bullets together.
Maybe we could start with like 3 categories, like;
-fragmenting
-expanding but not fragmenting
-non-expanding
...and go from there?
www.longrangehunting.com
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