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Old September 20, 2014, 08:21 PM   #26
James K
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The coned breech (which was designed for easier feeding) is somewhat of a weakness, but with good cartridge cases is not a problem. The problem with the SHT 1903's was that if/when a cartridge case did let go, the sudden impact of that high pressure gas shattered the receiver, breaking it into pieces. We don't think of an invisible and sort of insubstantial thing like gas having an impact, but it does, and that impact is a very hard, fast blow, not a gentle push. And it is that kind of blow, whether delivered by a hammer or by fast moving gas, that breaks those brittle old receivers.

Make no mistake; ANY receiver on a rifle like that which has experienced case head failure would have been damaged, almost certainly beyond repair. The sidewalls would have been bent outward, the magazine bulged and the floor plate blown out, but a good receiver would have held together. The brittle ones didn't.

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Old September 21, 2014, 09:16 AM   #27
F. Guffey
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The M1903 has a major design flaw; the coned breech. The rear of the cartridge case is unsupported for about 1/10 inch. A cartridge head separation in a coned breech rifle is often a catastrophic event. Couple the coned breech with a soft cartridge case and you have the recipe for a kaboom. The original M70 Winchester and the M1917 Enfield rifle also have coned breeches.
The coned breach: Before I knew scary music followed 'coned breach' I measured case head protrusion and case head support on the M1917 and the 03. 03A3 etc.. I found less case head protrusion and more case head support on the cone face barrels than on other receivers. Case head protrusion on the M1917 and the 03 is .090" when measured from the bottom of the extractor groove. that is .020"+ more support than most Mausers.

More support, the P14 chambered to 303 British has a rim that protrudes and most of the case is supported by the chamber, a few of the P14 went through for repairs, some of the barrels had a gas escape cut in the face of the barrel in front of the rim and over the top of the chamber. then to really cut down on the possibility of hot, high pressure metal cutting gas escaping the British drilled a hold through the chamber in front of the receiver. that one drilled hole through the chamber dropped the price down from $400.00 to$50.00.

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Old September 21, 2014, 09:39 AM   #28
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then there is the case, as I have said before in the form of a question "Who measures?" It is rat after that the snarky(s) get snarky. Military case heads have a case head thickens of .200", R-P commercial 30/06 case head thickness is .260" (there goes the theory surplus is thicker than commercial).

rather than talk about it I suggest someone purchase tools to remove a barrel, measure from the case head forward and from the front receiver ring back to the bolt face. With a military case and 1/10"? (.100") protrusion the case head is supported by .100".

Meaning? It takes a lot of pressure to blow a plug out of the side of the case at the extractor cut. Then there is case head separation, and for me a boring story always starts with "Hatcherr said ...."

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Old September 21, 2014, 12:00 PM   #29
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rather than talk about it I suggest someone purchase tools to remove a barrel, measure from the case head forward and from the front receiver ring back to the bolt face. With a military case and 1/10"? (.100") protrusion the case head is supported by .100".
Yep, i've got the spiffy tools and have done that stuff, many times.

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Meaning? It takes a lot of pressure to blow a plug out of the side of the case at the extractor cut.
That is true with a properly made new cartridge case. With a soft case or a case that has been reloaded numerous times maybe not so much.
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Old September 21, 2014, 02:42 PM   #30
F. Guffey
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AND THEN?

There is crushing the case head. When the case head is crushed the thickness of the case head from the bottom of the cup above the web and case head is reduced.

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