Stiga rifles and European Nito Proof Testing

[Potashminer]

I own two Swede 96 in 6.5x55, one Husqvarna 648 in 8x57 and now a "new to me" Stiga in 30-06 - all, of course, built on the Swede M96/M38 action. The Stiga appears to be built on a surplus Swede 96 made between 1918 and 1923 (the receiver stampings are ground off, but the serial number starts with H.K., which would be Inspector Helge Koltoff - I stand to be corrected on the dates). I have found lots of opinion expressed on Internet regarding the conversion of Swede actions to longer cartridges, but not much regarding reference material to support those opinions.
Two things I notice about the Stiga - the cartridge feeding ramp has been shortened about 1/4" to accommodate the extension to the front of the magazine (thereby reducing the depth of the material supporting the lower locking lug), and there is a "proof" mark on the barrel. The proof mark is a "crown over SL" (the SL is in cursive font) Beside this mark is "Nitro Test". It appears "from the Internet" that the Stiga barrels were made by Schultz and Larsen in Denmark for Stiga, and I presume this is their proof mark.
So, I am curious about how proof testing is done. It would seem to me that a proof test would minimally require a chambered barrel, installed and headspaced in a receiver, with a proof cartridge seated by the bolt. I can not see how a barrel alone could be validly "proof tested". I also doubt that a production run of barrels could be "proofed" on a universal receiver, since each barrel would have to be chambered and therefore individually head spaced to such a universal receiver. Does anyone know if the proof testing that is marked on the rifle barrel is actually a proof test of that barrel only, or if it is a proof test of the barrel, chamber, receiver and bolt assembly?

 

[Baribal]

It's a proof of the assembly. Just keep in mind that Sweden never joined CIP so they have their own laws / rules as for firearms making, but it usually mimmics the CIP ones.
The rifles usually are tested with proof loads of 1.25 X the MAP of the said caliber.
Also, for these rifles, they used a very long throat which considerably lowers the peak pressure when fired. And yes, some of the Stiga barrels came from S&L.
Forget about any previou inspector marks as the action was taken from a military rifle which was used before de-militarizing.

 

[Potashminer]

Thank you for the information, Baribal! Since the assembly is proofed together, that should alleviate any concerns about the "safety" of these conversions for MAP pressure level loads.

You were certainly correct about the throating! Using both Winchester bulk 180 grain spitzers and Speer 165 grain spitzers seated backwards, it appears that the throat of this one is in the order of 2.700" from the bolt face (headspace checks perfectly with Forster SAAMI gauges) - so, about .200" from max case length mouth to start of rifling.

Regarding the Inspector mark - since the markings on top of receiver are removed, I was using the Inspector mark to guesstimate the actual original date of manufacture of the receiver itself, when it was made for the Swede military.

 

[Baribal]

A lot, if not most of these "sporters" were made from M/94 receivers / bolts as a large quatity became available by mid '50 'til the '70s.
As for action strenght goes, if something as to happen, it will start by headpsace growing, a sing of set-back and a "built in" safety Mauser designed. With the loooong throat, there should be no problem regarding case head separation, so you're good to go.

 

[Potashminer]

You are "bang on" regarding the M94 business. Thank you! I found in the book "Crown Jewels" that H.K. was Inspector at Carl Gustav from 1912 to 1923, and this receiver's serial number 784XX matches up with M94 serials for 1916; else, that number belongs in 1900 production of M96's with different Inspector G.F. So it is indeed an M94, complete with typical M94 bent bolt (not a sportered type bend).

According to that book, "When horses were phased out in the 1950's, so were the carbines in Swedish service" (p. 57)

You, sir, are a bounty of information of things Mauser and Swedish!