Discussion in 'Gun Project Questions & Gunsmithing' started by Borisserge, Mar 18, 2019.
Who’s brass is being use for the test - tight chambers push pressure up even more don’t they.
I still don't see how a even test can be made. tight chamber, tight neck, loose or tight neck tension, different bearing surface length on bullets, bullets jammed or jumped, annealed or old brass , groove diameter of barrel all will reflect in pressure....
they just tested a double rifle in 500 nitro and a cannon right before it- what could go wrong?
I’m remembering why we kicked the “King” out. Maybe you should move over to our side of the pond.
Because rifle ka-booms are a serious threat, and, look around, we’re almost out of humans.*
*Note for the excessively literal: mild sarcasm.
Does the barrel have a short throat? The closer the bullet is to being jammed the more pressure it will create. Might consider pushing it out a bit. A 25% overcharge will definitely give a sticky bolt lift in any action. Is the bore a tight bore?
H.P White is one of the few companies that does proof testing in the US. I've talked with them at length, but it's been a long time ago now. As I recall, they tested at way beyond 25% over. I think they use their own receivers specifically for this purpose and special proof barrels with copper slugs that are used in establishing CUP, or copper units of pressure. The barrels have a hole in the chamber area that the piece of copper fits into. The amount of crush that the copper shows after firing is the measure by which the pressure is measured. That's the gist of how it works anyway. I may be off on some of the details but you get the idea. I guess one could google something like cup pressure testing for more detail on the procedure.
Just another preview of coming attractions------too damn much government !
Thats for getting CUP pressure from a load- like for factory loads. Proof testing is using the actual gun in its final form with a 20% over max load fired in it. They do the loading with their stuff so worrying about what bullet or case or even powder is a moot point.
Your last sentence indicates that you may have a serious misconception as to the construction of aluminum actions. Actions of that type have a steel insert that contains all of the forces that result from a cartridge being fired. The barrel threads into it, and the bolt lugs engage abutments that are part of it. Experience has shown that these inserts are not prone to failure. I have never heard of a single instance.
What likely happened was that several factors combined to make the bolt require more effort to open after the proof shot, none of which had anything to do with eminence of failure. One could have been chamber finish. There are others. I think that it is fair to say that the number of rebarrelings that are done in this country is probably several orders of magnitude greater than in the UK and I cannot think of a single example of a problem from that work being done that was due to material failure of the action or barrel. Most that I have seen were do to someone using the wrong powder, or some defect in the brass case, either a manufacturing defect, or caused by repeatedly reloading a case without proper attention to shoulder set back during the process.
We , our government, proves every military rifle when built = was called the blue pill . I forget , but I think 3 std rounds with the blue pill next . If headspace was still good it passed . The blue pill was in the neighborhood of 70,000 when the 30-06 was 48,000-50,000 . Well over the 20 percent the Brits use .
I've read that the Brits use to also oil the chambers while testing but that was in the days on SMLEs if true .
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