Raised Headstamps


#1

The question of raised headstamps seems to have emerged. Do we have raised headstamps on record? It just seems to me to have been a lot easier (cheaper?) to have produced a negative, engraved, bunter than one with + profile lettering? Obviously I can think of issues like headspacing but I would have thought these issues could have been managed.


#2

Russian 7.62x54R, 12.7x108 and 14.5x114mm rounds (as well as others from other countries) used raised headstamps. These were made as you say by a bunter with an impression of the headstamp engraved into it. To me this has always seemed to be the more economical way of doing it.

Here is an example of a raised 14.5 x 114 headstamp from municion.org:

Most (but certainly not all) rounds of this calibre used raised headstamps. The headspace wouldn’t be an issue as the impressed ring doesn’t cover the whole case head.


#3

Falcon, you are correct of course. It is much easier to change hs bunters when necessary + the wear is lower than with traditional ones.
You can add the 7.62x25 TT, the 20x99R ShVAK and the 23x152B (+ some CADs) to the range of Russian made calibers where this was/is done.
Worth to notice that not all countries which produce Russian calibers do follow this system.


#4

So, if it is more economical to produce raised headstamps, why is the majority are NOT raised?


#5

Besides the Question of Economics in Bunter production, the question of where to place the raised HS is also germane to the situation of headspacing.
One will notice that Raised HS are usually found on a bevelled rim, or in some other situation which will not affect headspace tolerances. ( ie, in BP Cartridges a lot of raised HS were on the outer rim of an “A” type head; Whilst in post-1895 Italian cases, the raised HS was in the Head groove; IN later Russian Large calibre shells, the Raised HS is in a deeper machined channel around the Primer, leaving the Main contact surface for HS purposes untouched.

Now, as to the economics of Bunter production, the traditional “Impressed stamp” bunter is made using Coin Die technology…First a “Hob” is created ( reverse image, Engraved, and then hardened. The Bunters are then pressed into this “Master” as soft steel, and the resultant “Coin image” is then Hardened to give the final stamp. Many Bunters can be formed from One Hob…

Now the “relief HS” system, requires the engraving of each individual HS Bunter ( although the Hob method can be used here as well, either by creating TWO hobs, or by simply engraving a single “Reverse” Hob (much more involved work) to creat the “Bunters”).

The other disadvantage of “Relief HS” is that the relief can be worn away over time, by either Firing pressures or friction, making Identification of the Case difficult, especially in BP days, when many Cases were regularly reloaded by both Military and Civilan users.

IN larger diameter cases, HS Bunters can be of the “Assembled” kind, where individual stamps are set in a Tool holder, to apply the impression…hence there is not the high cost of making a “one-piece Bunter”…changes of dates etc can be accomodated by simply changeing out individual stamps. But this system is not suitable for Rifle sized cases, for metal fatigue and size considerations of the Bunter head.

One other thing to keep in consideration, is that the “Work Hardening” of the head of smaller cases (ie, SAA) is affected by how the headstamp is applied, in fact, the Italian “ring channel” system was applied because the head of the M1891 case was too soft, and required an additional Hardening, to make it more reliable ( M91/95 case–the inner ring also aided in sealing the Primer cup in place at the moment of firing as well).
The US adopted this “Ring Hardening” system for .30 cal AN-M2 Ammo from 1918, and the French used it in 7,5 MAC M29 cartridges, and after 1949, in Fr. Made .30cal as well ( even though both US and Fr. used a simple, impressed HS).

Regards,
Doc AV
AV Ballistics.


#6

The original 1873 45-55-405 Carbine cartridge is a good example of a raised headstamp. They were very short-lived and many were destroyed, so they command a very high preminum when found.

For cartridges of that period I doubt if the headspace issue was serious enough to demand a switch to impressed headstamps. Most rifles of the day were probably long on headspace and the raised stamps may have even been beneficial. It’s a different story today.

The old methods of making bunters was time consuming, expensive, and required the skills of master die makers. Today, a programmed machine can turn out bunters in a fraction of the time and cost.

Doc - I believe the hob is an exact image of the headstamp and the bunter is the reverse image.


#7

Dear Ray, yes, you have it right…I meant that the Hob is the reverse of the Headstamp Bunter; Just my absence of clarity in grammar. Of course it (the hob) is Identical to the finished headstamp (in the shell).
And nowadays, Bunters are more than likely directly formed by CNC Electro-erosion machines (Just as they do in a Coin Mint, only that the CNC works from a large scale (5x or 10x) Hand-made Model ( Just like a reduction Pantograph).
The “Geometric shape” of a Headstamp can be CAD from a computer program of the design, thus eliminatign the need of the “model”.

The use of Computer headstamp Bunter Generation also makes Forensics a bit more difficult, as the Bunters don’t have as many “Individual differences” as they used to under the Hob and Bunter system, so differentiation between Case lots is rendered more difficult. LIke “Cloning” Fingerprints…the wonders of science…

Regards,
Doc AV