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A rule of thumb I was taught when I shot for the All-Army Rifle Team back in the early 1970's was one MOA change for every 15 degrees of temperature change. Thus, if you zeroed your rifle at 60 degrees and then later shot it in 15 degree weather, you'd be 3 MOA low. Of course, this was shooting Lake City Match ammo in Match Grade M-14's. I still shoot Lake City Match .308 ammo in my Ruger 77V, and find this rule of thumb is still pretty accurate.
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When I was with the team....we found that when shooting the .30x338 Any Any Rifles and the 220 gr. SHPMK from 1000 yds. that a change in temp of about 20F would change our zeros about 1 MOA for each 20F change either way! [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]
Steel chemistry… Now I am Not a metallurgist, so I would contact one and ask them; “is there a difference between the two steels and is it not recommended to use the stainless in Cold environments?” For information purposes.. Kreiger Barrels states “that a chrome moly barrel may take longer to break in than stainless steel because it is more abrasion resistant even though it is the same hardness. Chrome moly and stainless steel are different materials with some things in common and others different.”
I mention this only to note a difference between the two steels. It is my understanding that Stainless steel is heavier, and softer than Chrome moly. This is one reason why the Bench-rest shooters utilize it, and one of the reasons that some Gun smiths would rather work with it.
In any regard, it has been conveyed to me that Stainless can become brittle in the cold; and it is my own personal experience that throat erosion has occurred much faster and aggressively in the Stainless barrels when shooting calibers such as the 6mm Remington or the 6.5 X 284, than in the chrome molly. Personally, I prefer not to use Stainless Steel Barrels any longer.
As far as correcting for temps…. Yeah, I kind of agree with you. And since you shot witht the Teams... Shooting the .300 win mag “White Box” with the Lapua load; there is a drop difference at 1,000 yards of 1 moa (almost exactly) when going from 70 degrees F to 30 degrees F. However at 700 yards, the difference is .25 moa. So out to 750 meters, the difference is not as bold.
As a welder fabricator and journeyman millwright I used to work with both all the time. Stainless is far harder to machine than chrome moly. I challenge you to bust out some high speed steel drill bits and try to drill a hole through any piece of stainless. On just one hole you will dull many bits trying and when it breaks through you will break the bit. Now take same set of bits and drill some chrome moly. It drills nicely hole after hole. Stainless is used in industrial applications for its heat and erosion resistance. Now take both and try to cut them with a torch. You will whiz right through CM but when you get to the stainless you are done A torch with the oxygen stream going is way hotter than the temp of some burnt powder. This is why stainless is used in bench rest because the throats lasts longer in the heat of firing. Now days the only reason to use chrome moly for a barrel is if you are dead set on having it blued. As far as reaming stainless it takes special feed rates, special cutting fluids and an understanding that stainless work hardens as you machine it so once you stop or back the reamer out it is hard to restart it. It helps to drill it as close as possible before you bring out the reamer to finish it up. Was the reamers in question carbide or HSS?
The properties of stainless are not changing enough between 200+ degrees and 60 below to cause it to be brittle enough to crack from shooting or affect hardness measurably.
__________________ Some kids want to be a fireman or a doctor to help people. I wanted to be a gunsmith.
It is posts like these that leave me shaking my head. Who is right, who is wrong. Someone has to be, and according to you guys it is me. However, Mr. Krieger has conveyed his sentiments without reserve, that he prefers Chrome Molly Steel over Stainless Steel for barrels. He also states that SS is softer, that the throats polish out easier; and as I previously mentioned, is heavier, takes less time to break in, and is not recommended for freezing climates. I don't think that this has anything to do with his "Ideas" being turned around, and in fact he works extensively with metallurgists to obtain the best steel for the manufacturing of his barrels, period. But you can argue with him all you want; all's you have to do is phone him. Their contact information is s follows: