Strength of Krag actions

[Jim K]

To get back to the original question, P.O. Ackley's tests are reported in his Handbook for Shooters and Reloaders, Vol. 1. I don't know if it is still in print, but used copies are around. The trouble is that the results are about worthless. He proved that rifles will blow up, something most of us already know and that people knew then. He had no pressure taking equipment, so comparisons are not possible.

He did not use any discernable methodology, simply setting out to find a load that would blow a rifle. The results are interesting in showing HOW rifles fail, but of little value in showing at what point they fail. He might blow up one gun with A grains of B powder and another with C grains of D powder, proving nothing except that those particular loads would blow that rifle. He even used heavy charges of 2400, which would probably blow any rifle ever made except possibly a Remington 700, and likely would harm it.

I don't doubt Ackley's basic findings, but I wish he had been more scientific about obtaining the results. He did debunk some myths, especially the one common at the time that the Japanese Arisaka was total junk, made of cheap tin or scrap iron, and that the 98 Mauser was a superstrong product of German engineering and would never fail. Both views were nonsense, and Ackley proved it.

Jim

[jon_norstog]

Jim,

Excellent post. It's obvious that you have a sense for scientific method, something that kids don't get taught much in school, and that a lot of people are openly hostile to, especially when they disagree with its results.

Keep it up!

jn

[richarda]

No "?" on the Model 1885 Winchester Single shot in .30-40; Col. Whelen wrote about his, and I've seen a picture of it. There were a few Remington-Hepburns, too.

[Oldyoti]

Warning: I can not verify this post, as Fred Telke has been dead for ~30 years. It is true to the best of my knowledge.

My father-in-law shot a Krag competitively during the '20's to 30's. He experienced a cracked bolt lug. As a tool maker he had access to all the tools, and heat treating equipment needed. He had taken some college level metallurgy classes so he took the bolt to the prof. The professor concluded that the bolt was indeed brittle, but that one made of a different alloy, and heat treated properly would be much stronger. Fred made one and used it in competition for many years.

Unfortunately, after he married in 1939 the rifle was sold as he stopped service rifle competition.

This is an interesting tid-bit you've posted. Understanding the botched metallurgy of many if not all of the US Krag actions to some degree, coupled with the brittle bolt's single forward locking lug, backed up only by a non-bearing bolt-rib safety lug, it's obvious the reason for limiting these rifles to mid pressures at most.

By contrast there is the Norwegian Krag, which to my understanding was produced with correct metallurgy and processes, then it was case hardened. Work was applied to the bolt as well making the bolt-rib a true second locking lug, bearing against the action's rear ring through careful fitting at the factory. Though not as strong as most dual forward lug actions, the "Norge" Krag is quite a bit stronger than the US Krag...

If manufactured today with modern alloys, with both lugs working to lock the action, how strong would this smoothest of bolt actions become... any thoughts?

[westkraut]

"Contrary to some rumors, the Krag-Jørgensen action can be modified to fire modern, high power cartridges. During World War II, and also in the early 1950s, several were produced in 7.92 x 57 mm, which can hardly be considered a low power cartridge. A number of Krag-Jørgensens have also been converted to .30-06 and 7.62 mm NATO for target shooting and hunting. However, it must be stressed that these were all late-production Norwegian Krag-Jørgensen rifles, made in an era when metallurgy was vastly more advanced than when the American Krag-Jørgensen rifles were made. The American Krag-Jørgensen also has only a single locking lug, whereas the Norwegian and Danish versions effectively had two lugs." Krag-Jørgensen - Wikipedia, the free encyclopedia
The CIP MAP for the 6.5 × 55 is 380 MPa (55000 PSI). SAAMI MAP for this cartridge is 46,000 CUP or 51000 PSI.[2] All Swedish Mauser actions were proof-tested with a single 6.5 × 55mm proof load developing approximately 55,000 CUP (66,000 psi).[3]
-- P.O. Ackley. In his words "It gave no trouble even with powders as hot as #4198 in quantities sufficent to require compression to get in the case. Such loads blew the primers but did not hurt the action." He ended up with a case full of 2400 before the action ruptured and even then it wouldn't have done serious injury to the shooter. He tested four actions, two standard and two that had been re-heat treated. All similar results.

---------- Post added at 06:02 PM ---------- Previous post was at 06:01 PM ----------

And Ackley would have blown up Remington 700s as well!

[Oldyoti]

In a recent trade with a friend in exchange for some shotgun parts, I inherited a complete barreled action, a 6.5x55mm Norwegian Krag with a poorly done flat-gate magazine conversion... Otherwise, the action and bolt are tight and serviceable. The painted barrel and it's bore are in excellent shape. It looks like one of the sporterized models since it is fitted a leaf-spring elevator ramp and buckhorn sight on the rear and a ramped leaf on the front. Centered at the top of the 23" barrel, just ahead of the receiver ring is stamped "Swedish M-94"... the 4 is stamped sideways like a "lazy-4".

A hobbled up stock from another rifle came with it... I checked it out thoroughly then picked up a box of PPU 139 grain 6.5x55 ammo, my chronograph, and headed for the range.

Once there, I opened bubba's flat-gate and rolled 3 rounds into the magazine, closed the flimsy hatch and fed the first round into the chamber. I aligned the sights on the target and squeezed it off. The recoil caused the loading gate to fly wide open... it opens forward like a Danish Krag, with a simple hinge and a poorly engineered snap lock. I taped the damn thing shut and fired the rest in single shot mode.

The rifle handled the factory ammo just fine, no signs of pressure, no primer flattening or primer movement at all, and the cases showed good chamber contact all round... it is obvious it will handle much more. The average velocity was 2381fps with a high of 2411 and a low of 2347. Seems about right for factory stuff thru the short barrel on this Krag.

Now, to fix the badly bubba-ed loading gate and what is left of the carrier assembly... this will take a little time to work out since the magazine box's lower gusseting has been completely hacked off.

[kragluver]

I believe that US Krags were set up with only the locking lug bearing in order to simplify manufacture and improve interchangeability. Springfield was anal about interchangeability. That they weakened the action probably didn't occur to them. The rifle met their requirements in 1892 and perhaps they couldn't envision needing a rifle that could handle more than 45 KSI. Keep in mind that a 220 gr bullet at 2000 fps was really smoking in 1892!

The Krag actually has two safety lugs - the guide rib and the bolt handle fitting into the receiver mortise.

There is a gentleman that posted the story over on KCA of milling off the locking lug and then testing the Krag with full power loads without the locking lug with no I'll effects. I forget the charge he had to use to finally cause failure but it was well above any normal pressure a Krag should ever see! Oh, and the bolt held even in failure. The receiver ring failed as it did in Ackley's testing.

[westkraut]

Ruger in #1 and some Husqvarnas were commercially produced in 30/40 Krag for sport hunting as well.....probably others on a short term production runs that died out as "superior" rounds and rifles were produced