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Very interesting design. Will it be necessary to mill in an extractor relief for the rolling block rifles or does it make any difference? Taking off the extractor and pulling the firing pin on K-J rifles is easy to do, so there wouldn't be any problems there.
 

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Well, I think all of you have some good ideas about headspace and chamber measurement, and obviously some seasoned experience, so I appreciate the information. What Dutchman is doing should have been done a long time ago, but after a brief flurry of interest 40 years ago the 8x58RD was simply forgotten, until the last few years when the Swedish rollers started entering the market in relatively great numbers. There should be technical documentation in all three countries about the development, testing, and finalization of the cartridge. I know Rubin of Swiss firearms fame helped in a part of the development of the 8x58RD. Unfortunately there was a terrible explosion at the Hærens Laboratorium in København in the 1890s and many records may have been destroyed. The Nazi occupation of Denmark really stripped the country of K-J rifles, so even after the war the Danes had to rely on the Allies contributions and the use of the captured German Mausers.

Anyway, I'm glad to see Dutchman doing this and I will gladly volunteer to field test the prototype gauges whatever their final configuration.:D;)

Now, if we could just get some reliable pressure data -
 

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Dutchman, I agree on the 28,000 psi "best educated guess that we can make at this time". At least for the m/67-89 rifles. When we look at similar rifles of that period with known pressure limits based on some repeatable type of testing with reliable instrumentation, we can extrapolate ranges of pressure that are safe in guns of good condition without flaws in the metal.
With a combination of testing with one of the excellent internal ballistics computer programs and the relatively inexpensive piezo strain gauges available now, we could develop a set of loading parameters that are known with certainty.
I have been looking at the RSI strain gauge setup and would love to glue sensors all over my rolling blocks to see what I can find. Since my funds are limited for that stuff, I've also been writing to the various companies and manufacturers trying to get someone interested in testing the cartridge to develop that knowledge. H.P. White labs used to test loads for individuals (or so I've been told), but I don't know the cost or if they will still do it. Need to find that out.
Dutchman with your knowledge of metalworking what are the possibilities of making a pressure test barrel? Then there would be a permanent fixture with bullet trap and permanently affixed sensors. No need to depend on the old rifles and fiddling around at the range when the weather is good. It could even be set up in a basement or a workshop. I know some of the die and reamer makers have chamber drawings that they will sell to individuals.
Wouldn't that be some setup! Load up a batch of test cartridges at the reloading bench, walk over to your own pressure test barrel, fire away, and then start analyzing the pressure curves and readings on the laptop computer sitting on the bench. I think it is do-able.
 
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