Confusion on LN 03's

[swampyankee]

I have read all the warnings on shooting LN receivers. I understand that the receiver may handle a pressure round, but it is the way the receiver handles a case head separation or other cartridge related problem that will cause a KaBoom.
The question I am wondering is if the Krags were heat treated the same way, why do we not hear about Krag receivers blowing up or shattering when hit with a hammer. Wouldn't a case head separation blow them up.
Inquiring minds want to know.

[Rick the Librarian]

Krag ammunition created much less pressure - that was one reason the M1903 was developed.

[swampyankee]

Krag ammunition created much less pressure - that was one reason the M1903 was developed.

So if I reload my LN 03's with 30-06 at 30-40 Krag pressure levels, they are safe to shoot?

[Marine A5 Sniper Rifle]

LN 03's are safe to shoot with the ammo for which they were designed. We have a LN 03 hunting rifle in our family that has been used for over seventy years with commercial ammo with no issues. The kids fight over who gets to use it. Five generations so far.

jt

[Ketoujin]

Hi All,

Well, at the risk of sounding like an outright apologist for LN '03's let me preface my comments by first stating that I, myself, err on the side of "better safe than sorry" and wouldn't shoot a LN despite that fact that the likelihood of a catastrophic failure would be low, especially with mild hand-loads.

I would like to add however, in the vein of Marine A5 Sniper's comment, that a man in my local community bought a LN '03 in the 1950's - an SA with a 1905-built receiver. He, like so many did at that time, had the gun sporterized and carried it on board the USS Wahoo II submarine on which he was a part of the engine room crew from roughly 1956-1961 or so. (Incidentally, his XO was William Crowe would later reach Flag Rank and become the Chairman of the Joint Chiefs of Staff immediately preceding Colin Powell in the post. My local contact remembered that XO Crowe was often seasick.....this on the part of a submariner!) On arrival in Yokosuka, Japan he swapped the cut-down issue "S" stock for a finely-carved sporter stock made "on the economy" by a Japanese carpenter. During several subsequent cruises throughout the Pacific and adjoining seas and oceans, my contact had several opportunities to fire his personal rifle when the boat was surfaced and during the required periods of small arms firing and practice when the weather and ocean conditions cooperated. He fired the Navy issue M2 ball kept aboard ship for use in the BAR's kept in the small arms locker in his '03 with no problems.

Just another LN anecdote I found interesting.....although I myself am far more cautious....which I suppose I could put down to temperament.

Best,

Gunnar

[Parashooter]

To answer the question specifically, the design of the Krag's chamber, breech, and cartridge is very different from that of the M1903. The Krag cartridge is rimmed, lacking the deep groove ahead of the rim needed to enable extraction with a "rimless" cartridge like the one used in the '03. As a consequence of this, the Krag cartridge seats fully into the chamber and the bolt face completely surrounds the rim. This leaves virtually none of the brass cartridge case exposed and helps ensure that even if the case should fail, little or no gas can escape. In addition, the Krag's breeching system provides that any gas which does escape from a failed cartridge is vented directly to the atmosphere where it can dissipate.

In the Model 1903, the cartridge enters the chamber only as far as the front edge of the extractor groove, leaving significantly more of the brass case exposed. The bolt face flange is also partially cut away to provide controlled feed, leaving more brass exposed. Furthermore, any gas escaping from a failed cartridge is not vented directly outside but enters the semi-enclosed space encompassed by the receiver ring, where it is offered a substantial area to damage the surrounding steel.


Yellow dotted line shows how far cartridge enters chambers of US M1903 and Krag rifles. Green line indicates extent of .30 Army ("30/40") solid web as compared to that of several .30/06 cases.

In summary, while the M1903 has a stronger locking arrangement, the Krag has a more robust breeching arrangement to mitigate damage from a failed cartridge case. Consequently, the Krag's integrity is significantly less dependent on strong and resilient materials than is its successor.

[Rick the Librarian]

Thanks for the detailed explanation, Parashooter, I knew the answer was a lot more "complicated".

[kragluver]

Excellent post Para! I knew about the bolt design comparisons but I had never seen the explanation showing cutaways of the cartridge heads. Most excellent. I'll have to file this one away...

[blackhawknj]

IMHO Hatcher's Notebook is THE source to read regarding the LN Springfield question.
He found the bad vintages were from 1906 and 1911 IIRC. Both the steel and the manufacturing processes were improved and the decision was made in the late 1920s to eventually withdraw the LNs from service, due to the tight defense budgets of those years that was not implemented.

[rcmkhm]

Very good post from Para. To expand on what he wrote, General Julian Hatcher was in charge of the investigation of the receiver failures in 1917 and he noted that the cartridge cases on the .30-06 round projected out the rear of the chamber a distance of from 0.146" to 0.1485", a distance of about 1/8" where the pressure during ignition was held in only by the brass. Anecdotal evidence seems to indicate that the softer brass composition used in cartridges being hurriedly manufactured for WWI, coupled with a decidedly more brittle steel in the single heat treated receivers, caused the known failures when the exposed portion of the cartridge that Para mentions ruptured in an area outside of the walls of the breech, which then caused lateral pressure against the sides of the receiver that were never designed to handle it. The reported cases of failures were, however, statistically very small and there were still reported failures of high serial number receivers into the late 1920s. Presumably, if the soft brass ammo from WWI had been exhausted around that time, that might explain why the number of reported receiver failures stops. Heck, those old LSN rifles never seemed to bother the Marines and they had no reported issues with later manufactured ball ammo.