Lg 1889

[Badger]

Thanks Bob....

MKL entry has been updated....

Regards,
Badger

Information

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[Bob S]

I found this in the "knowledge base" for Swiss rifles:


DO NOT shoot the M1889 Schmidt-Rubin using standard 7.5 x 55 Swiss (GP11) military surplus ammunition. The chamber of the M1889 was not designed to handle the pressures generated by the more modern GP11 round. The Model 1889 action was designed to handle rounds that generated at most 39,000 psi, while GP11 rounds produce 45,500 psi. It is safe to fire modern 7.5 x 55 Swiss (GP11) rounds in Model 1896/11s, 1911s and K31s. If you wish to fire your M1889, you are going to have to reload your own cartridges.

It is true that you should not fire GP-11 in a M1889, but the chamber isn't the reason. The concern is instability buckling failure of the bolt. In the Lg1889, the locking lugs are at the rear of the locking sleeve. The bolt assembly acts as long column with a wobbly joint in midspan. In the Lg1889/96, the lugs were moved to the front of the locking sleeve and made a little larger. This made the bolt "column" significantly shorter and stabilized the back end, eliminating the "wobbly joint". The larger contact area of the lugs allows for higher pressures without increasing stresses. Thus, when the GP-11 cartridge was developed, the Lg 1889/96 was suitable for rebarreling to the 7.5 x 55 cartridge, and nearly all of that model were so-converted and became known as the Lg 96/11. It was determined that the original Lg1889 was not suitable for conversion because of the bolt issue. The GP-90/23 cartridge was developed for the Lg 1889 so that users of that obsolescent arm would have a full metal jacket cartridge. Firing of GP-11 ammunition in Lg 1889 rifles was not authorized, except during the WW II emergency, when reservists and Landsturm who still held the rifle were told that they could use the GP-11 for "war emergency use" only.

The original GP-90 cartridge had a lead alloy bullet with an iron or mild steel "cap" at the nose; the assembly was then paper-patched. The bullet miked about .320-.321 over the patching. The neck of the 7.5 x 53.5 chamber was overly large to accomodate this projectile; and the leade of the chamber was both long and the angle very shallow to guide the projectile into the bore wihout tearing the paper patch. This is the reason that the Lg1889 did not perform paticularly well with GP-90/23, and the reason they don't do real well with our typical .308" bullet handloads (as compared to the rest of the S-R family and the K31).

I have done chamber casts of the three that I own; the length of the chambers on all is substantially greater than the "53.3" of the cartridge name. In fact, the chambers are long enough, and the chamber mouth is of such diameter that "pinching" of the case mouth of an errantly-fired GP-11 cartridge would not be an issue. A GP-11 cartridge would not be expected to generate pressure higher than that generated in a proper 7.5 x 55 chamber, and infact might be a little lower because of the freebore that the GP-11 bullet "sees" in that chamber ... but the pressure developed would be too much for the weaker, wobbly 1889 bolt to tolerate for any length of time.

Take Poyer's book with many grains of salt. Lots of errors in there.

Resp'y,
Bob S.