What does temp stable mean?

At -40, It's closer to .001" on a 1.00" diameter object. Which will actually generate more pressure. More so on 416r stainless.

When I shoot the old .283" Norma bullets in my 7mm WSM, and I shoot the exact same bullet, but the newer .284" diameter bullet. The newer one creates more pressure with the same powder change.
 
Alot of CNC mills use thermal expansion to hold the endmills/cutter in the tool holder now. Nothing more than heating the holder, placing the tool in, cooling it off, then chucking it up and using it. You can use it in manual mills as well. Has very minimal runout, and uses the same principle of thermal expansion.

Holding your micrometer the wrong way, or too long results in a improper reading as well. Metal contracts and expands way more than you think. And a typical mic only ready down to .0001. the larger the mic, the more it changes, and the more improvement it is to use it right, and have the environment you are in temperature regulated.
 
https://x.com/i/grok/share/AIsKGHxPliqqjtqlEFtFmxhGj

Denver Steve - That is really interesting that such a method is used to chuck tools - so simple, and similar to the blacksmith putting the rim on a wooden wheel. I wonder if a metal which has a lower coefficient of expansion would grip tighter because of the range of expansion would be less. (Just a silly wonder).

Also I wonder if pistons of aluminum and blocks of cast iron change enough in size from temperature change to make any difference in how they turn over in the cold - I suspect that being hard to start has a whole lot more to do with the type of lubricant - so I'm suspecting that the same goes for barrel bore - It could even be that copper jackets are more or less slippery in cold. There might be some simple explanation for the occasional increase in velocity in cold. I notice that near the muzzle is the place for barrels to rust because of moisture - which would be from water condensing inside the barrel - usually less than two inches, but I suppose that it could get in further and freeze as a hoarfrost ( like frost on an extension cord) - even a very thin frosting might allow the bullet to accelerate at a higher rate for the last inches of the barrel - but that would affect only the first shot. I can experiment with this - breathing down a cold barrel before shooting over the chrony.

As a rule, any rule we make has weaknesses - requiring that we admit weakness in understanding - my supposings are more wrong than right - so real data like we saw early in the topic is great stuff to listen to.

And I'm off to get the sleds fired up for when the grandkids come.
 
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