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Thread: Letter "P" and letter "K" marking on K98k stocks

  1. #1
    aka 8x57IS Stephan98k's Avatar
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    Default Letter "P" and letter "K" marking on K98k stocks

    In the last years I have read many assumptions about the meaning of the letter "P" marking on K98k stocks. These markings must have been important, otherwise they would certainly not have been applied to the stocks.

    The Mauser Oberndorf chapter, page 230-231 in the "Karabiner 98k Volume I" book is very interesting. In 1935 the development of alternative stock materials was started and early 1936 tests was completed. The result was that the walnut stock was better than the laminate stock and they said "such a stock cannot be taken into consideration for use during war". Nevertheless, in July 1937 Mauser Oberndorf ordered laminate beech stocks and in October 1937 the first rifles fitted with laminate stocks was shipped.

    Here are some previous assumptions about letter "P" markings:
    - the letter "P" is a code or abbreviation of the laminate blank provider
    - it's a subcontractor marking or lot identifier
    - it's a supplier that developed the first laminate stock blanks
    - it's a marking for a armorer stock
    - the stock was rejected and replaced during manufacture and therefore the marking

    Observations about these letter markings:
    - walnut stocks doesn't have the marking
    - the marking starts with the early laminate stocks
    - letter "K" isn't so common like the letter "P" marking
    - the marking was phased out around 1941 / 1942
    - laminate stocks have the marking and at the same time a different laminate supplier code in the barrel channel or behind the buttplate

    The problem in the first place is not the beech wood, the development of laminated wood has been vigorously tackled since around 1930 and a good solution was achieved by Mr. Kraemer in the department of the Deutschen Versuchsanstalt für Luftfahrt (German Research Institute for Aviation). The main problem was the gluing of the individual layers of the laminate wood. The beech wood has a high absorbency and is particularly suitable for soak-glueing with liquid synthetic resin glue. Different types of wood glue has been used and they had to observe how they behave in the coming months or years in daily use. Many layers of wood provide high stability, but the size and number of glue line negatively affected the moisture resistance, since the binding force of the originally used casein-glue drops a lot upon moisture absorption. But with the synthetic-resin-glue, in particular of the phenol type (Phenol-Formaldehydharzleim), water-resistant binders have been developed.

    In the early days these laminate stocks would certainly closely examined, as there were no long-term results on the durability of the glue of these laminate beech stocks. An external marking of the stocks with the different glue types would make sense, so that they could identify them quickly and easily if problems occur.
    I have named two known glue types, "casein-glue" and "synthetic-resin-glue of phenol type". The German names are:
    - Kaseinleim
    - Phenol-Formaldehydharzleim

    The Phenol-Formaldehydharzleim had advantages over the Kaseinleim and that could explain the much more common letter "P" marking on the stocks.

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    RKI- Reasonably Knowledgable Individual heavy_mech's Avatar
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    You've really been on quite a roll lately. I think the theory of those letters providing a quick look method of identifying which resin type makes perfect sense. I do agree that they would bear much scrutiny in the first few years because of doubts over it's durability. Well written piece Stephan.
    "Wen Tausend einen Mann erschlagen, das ist nicht Ruhm, das ist nicht Ehre, denn beinsen wird's in späteren tagen gesiegt hat doch das Deutsch Heer. Podest nicht die Paten der Soldaten doner die da Sterben sollen, soll man geben was sie wollen, sahs sie Herzen, sahs sie Küssen, den sie wissen nicht wann sie sterben müssen"

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    No War Eagles For You! mrfarb's Avatar
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    I know the early stocks have a "K" to denote Karabiner (as opposed to stocks made for the longer Gewehr). I don't recall seeing the "K" on many laminate stocks, so they must have been the unfavorable type. That said, I think the idea that the "P" could be an indicator of the type of glue is a great theory, and the only one I have ever seen that makes sense.
    Order the new K98k book at www.thirdpartypress.com
    Don't forget to visit www.latewar.com for info on late war 98k's.

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    aka 8x57IS Stephan98k's Avatar
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    You are right with "K" stamped on stock and sight components, in this thread "Another Karabiner 98k from Germany (42 1938)" we have a good example for both letter "K" markings.

    So far it is just a theory, I will continue to search and hopefully I can confirm this theory with documents.

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    Moderator² Loewe's Avatar
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    I find Stephans's argument compelling, certainly the most reasoned explanation so far. Too bad it didn't make the book, though just one more argument for a revised edition one day!

    By the way Stephan, your English is exceptional, grammar and style superior to the vast majority of English speakers one encounters. Obviously you were not educated in the United States...

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    I think this makes a lot of sense. Whatever the glue type the laminate stocks seem to have had up pretty well over the last 8 decades!

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    Senior Member flynaked's Avatar
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    I like the theory a lot sir great reasoning!! This brings up some interesting points and questions. While we see P and K, Czech stocks particularly have some additional letters that appear, possibly other resins? I feel as if there is a predominance for delaminations in Czech stocks for whatever reason, which is interesting. Also a wide range of glue colors are noted on Czech stocks as well which might indicate testing, red, white, green and pink, it would be interesting to trend the stock letters with the glue “type” in accordance with color. As you noted though both the phenol and casein resins are typically both red. Being largely hygroscopic as noted might have had a severe impact on the performance, this being an issue at the time of manufacture of course. Many resins have a very narrow range of acceptable humidity during lay up which can mildly to severely affect the bond. It’s interesting that some stocks I’ve worked on seem to have a rather strong bond remaining in the laminate and others have obviously suffered, UV degradation is one of the biggest killers that breaks resins down. Some show the same kind of crystalline break down that old Ester resins suffer. For people that like to shoot these OLD laminate stocks, especially matching, unsanded valuable ones, depending on the (apparent resin type) or conditions at manufacturer it maybe anywhere from okay at best to extremely susceptible to complete failure (delaminations). Luckily the bond is strongest in shear, however there is one other aspect of these resins and the stock design that makes them susceptible. The resin continues to shrink for a long time after it has cured, you can notice this on untouched stocks and it is one of the best indicators of an unsanded stock. Because of this however the shrinkage in the action area causes the cross bolt to become loose and without that compression the laminate bond begins to take more tension loads where it is weakest and then delaminations occur and then setback in the lug, ending with a split at the wrist as the action slowly hammers rearward. So do yourself a favor if you are shooting a laminate K98 stock and please tighten the crossbolt! The majority of rifles you come across have loose crossbolts because they have sat untouched all these years, no big deal if you are not shooting it, not worth the risk of damage to tighten it if not.

    Another food for thought item, many composite aircraft from the late 70’s/80’s had life limited airframes some to as few as 25years due to resin degradation, we are still shooting stocks with resin bonds from
    the 1940’s so please be mindful of this! Haha

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    Senior Member Eh jbmauser's Avatar
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    Some very interesting info in this thread indeed.

    I have nothing of value to add really but thought I would mention the use of pink glue in the handguards of a couple of my byf44's. Like Clay said, the use of pink and green seems to be more prevalent in the Czech stocks but it seems to have made it's way to other manufacturers as well, at least the pink.
    WTB: Rough milled, blued, unnumbered floor plate as found on late MO rifles. Unnumbered MO bands, both KM and standard type, MO KM stocks including an unaccepted one, MO bands and stock 5897, upper band 0643

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    Senior Member Mauserken's Avatar
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    Here is a Gustloff kkw with Zf41 that has the P on the keel. Wrist stamped Su27 and side stamped Su10. Metal is Eagle N and 749. Not sure if this helps ,but thought I would post a couple photos.
    Attached Images Attached Images

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    Keeper of the Def's Head M1903A3's Avatar
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    Quote Originally Posted by flynaked View Post
    I like the theory a lot sir great reasoning!! This brings up some interesting points and questions. While we see P and K, Czech stocks particularly have some additional letters that appear, possibly other resins? I feel as if there is a predominance for delaminations in Czech stocks for whatever reason, which is interesting. Also a wide range of glue colors are noted on Czech stocks as well which might indicate testing, red, white, green and pink, it would be interesting to trend the stock letters with the glue “type” in accordance with color. As you noted though both the phenol and casein resins are typically both red. Being largely hygroscopic as noted might have had a severe impact on the performance, this being an issue at the time of manufacture of course. Many resins have a very narrow range of acceptable humidity during lay up which can mildly to severely affect the bond. It’s interesting that some stocks I’ve worked on seem to have a rather strong bond remaining in the laminate and others have obviously suffered, UV degradation is one of the biggest killers that breaks resins down. Some show the same kind of crystalline break down that old Ester resins suffer. For people that like to shoot these OLD laminate stocks, especially matching, unsanded valuable ones, depending on the (apparent resin type) or conditions at manufacturer it maybe anywhere from okay at best to extremely susceptible to complete failure (delaminations). Luckily the bond is strongest in shear, however there is one other aspect of these resins and the stock design that makes them susceptible. The resin continues to shrink for a long time after it has cured, you can notice this on untouched stocks and it is one of the best indicators of an unsanded stock. Because of this however the shrinkage in the action area causes the cross bolt to become loose and without that compression the laminate bond begins to take more tension loads where it is weakest and then delaminations occur and then setback in the lug, ending with a split at the wrist as the action slowly hammers rearward. So do yourself a favor if you are shooting a laminate K98 stock and please tighten the crossbolt! The majority of rifles you come across have loose crossbolts because they have sat untouched all these years, no big deal if you are not shooting it, not worth the risk of damage to tighten it if not.

    Another food for thought item, many composite aircraft from the late 70’s/80’s had life limited airframes some to as few as 25years due to resin degradation, we are still shooting stocks with resin bonds from
    the 1940’s so please be mindful of this! Haha
    Fascinating stuff guys, lots of great info and theories here on these stocks and markings. This makes me think of the old Wilson Strata-bloc golf clubs, that were laminated rather than solid persimmon. I think they used maple. Today, these Wilson’s are often found in great condition, not delaminated at all. Whatever they used, it worked! The grips degrade but not the heads. Then again, they ARE pretty heavily coated in shellac! Great thread. We may get to the bottom of some of these markings yet!




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