I can’t really speak for this specific .357 cartridge, but a spectrograph of a .45 KTW bullet showed the projectile to be common brass, not berillium bronze or even common bronze.
DK will probably be along with exhaustive info. My recollection is that the composition of the KTW projectile, even the color of the coating, went through several iterations.
wolfgang, I am VERY interested in having you section a number of cartridges for me. PM me with your ship-to address, rates for labor, etc. (My attempts at sections of metallic catridges and projectiles have all been rather disappointing). I have at least 20 different cartridges I’d like to have sectioned for my collection, and for display/example during classes and testimony.
Seemed like brass to me while cutting, but I know nothing! Was told it is a “hand machined copper berilium flat base projectile with Dupont teflon”. With the earlier KTW marked case.
Some had Winchester case, or tungsten projectiles. Read that some bullets sat in a copper cup. One even had a black teflon coating, not green. Made in almost all pistol calibers.
The caliber made with a black coating was .44 Auto Mag. Until made illegal in California, I had a pretty good collection of KTW - not every known variation, but a lot of them. A friend at the U.S. Customs Lab (who is also a member of IAA) did a spectrograph reading on a KTW .45 bullet, after cutting it in half. I still have the note (I had the half bullet with the burn mark on it but somewhere along the line in the last twenty-five years or so it got away from me).
"Spectrographic results show bullet to be plain brass, not beryllium bronze even bronze. Powder charge is … (Deleted by John Moss since it is commonly available powder and therefore, violates IAA Policy); bullet weight is 185 grains.
Spectrographic Plate No. 920
Rack No. 86
Little: (Note - no entry in this field)
No Su be seen (I may have the “Su” wrong. It is definitely “S” but I have forgotten much of the table of element abbreviations, and it is handwritten, and I’m not sure about the second letter.
This cartridge was cut at a time when some advertising was still showing KTW as having Beryllium Bronze bullets. In fairness to them, it may have been during a transition to plain brass - I simply don’t know so will not intimate that they were falsely advertising.
I was under the impression that the earlier KTW brass projectiles which started out in .380 auto, were the hardened beryllium bronze variations or whatever kind of hardened brass it was they were using. Later, NAO was using plain brass, and all of the NAO stuff was brass towards the end (1985-ish). This is also when NAO was using a green coating that was nylon and not Teflon. So the metallurgy and the coating was sort of a cheaper knock-off (They still penetrated relatively well, but not as well as early KTW). This is why the typical penetration tests from magazines, etc. done with KTW blunt ogive .45, 9mm, and other calibers usually have poor results - they are the later NAO version of plain brass.
Of course, the teflon or nylon was not there for matters of penetration, but rather to protect the bore, possibly needed if the originals were, indedd, Beryllium Bronze. Much ado was made about the teflon coating by ignormus reporters and law enforcement officials that should have known better.
John–The chemical symbol for beryllium is “Be”.
Some of the early KTW were made from Kennertium W-2 which is a sintered product of powder with a nominal composition of 97.3% tungsten, l.4% nickel. 0.7% copper and 0.1% cobalt
Ron - thank you. That symbol did not appear on the spectrographic analysis of the .45 round because there was no Beryllium in the bullet metal at all. I don’t know what “Su” is or if I typed it wrong. that is the one which I questioned.
could be Sn tin which is alloyed with copper in many applications
Vic - I think it is tin. Thanks.
The topic of projectile composition for the KTW line makes me wonder if there has been a scientific evaluation of different alloys in regard to penetration capabilities through the different medium intended as combat handgun targets.
My line of thought here being that: Is there is any advantage to a composition harder than something like 70/30 brass at handgun velocities given an equally well designed nose profile? I would assume there is a whole different set of issues at rifle velocities, but below 1500 fps how much difference does projectile composition make?
John Moss? DK?
DaveE - It all depends on whether you desire to penetrate metal or soft body armor. The 5.7x28 and 4.6x30 along with other PDW type calibers were all designed with penetrating helmets and soft body armor in mind. Being able to penetrate standard vehicle doors was a tertiary goal and these can sometimes do that as well. You can have a small projectile, or a softer metal core / projectile made of aluminum or brass as long as it is super high-velocity. If it is a larger caliber like .45 .44 .38 etc… then steel will penetrate better than brass, but this is all dependent on ogive shape, and the length of barrel can affect velocity. There’s so many variables. The absolute best penetrators are the small caliber high-density saboted ones like the 6.5x25 CBJ, which is along the same idea lines as the .308 SLAP rds. The 9mm Snail rd that Libra used to make was a hardened steel penetrator in a uniquely shaped brass projectile that would collapse on itself when hitting the target, and this forced the penetrator forward. In terms of practicality, it seems like governments and agencies will go with whatever is cost effective at being able to penetrate just enough Kevlar & helmet to be useful to them. I assume that this is why the 6.5x25 CBJ has not been picked up by any agency - it penetrates too well. You might not want to shoot clean through a vehicle or person depending on what is behind it. I still hear people report that the German wartime 08mE 9mm projectiles penetrate very well with their iron cores and standard round nose jackets, and those might have been just under or at +P levels?
Thank you for that very informative response. There would seem to be a lot more to the topic than I was thinking!