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Old August 11, 2013, 08:32 PM   #30
Metal god
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Join Date: April 10, 2012
Location: San Diego CA
Posts: 1,976
Quote:
what would a chrome lined chamber offer? Any advantage?
Again it helps cleaning and from carbon from sticking to the chamber .It can help with extraction because the chrome lining will have a bit more lubricity then raw carbon steel . Some times when the case does not seal the chamber when fired you can get carbon build up in the chamber more up by the shoulder and neck area . You see this more with steel cased ammo do to the fact that steel cases don't expand and contract as well as brass cases do . This can cause extraction issues and a chrome lined chamber could help . All of that will be a non issue if you keep the rifle clean-ish .

I really feel I'm getting to the point that I'm talking over my head on this issue . I do not have a huge amount of knowledge when come to metallurgy and internal ballistics . If some one else could add to or even correct anything please do .

As for twist : I agree that 1-8 / 1-7 is good . Really 1-9 will shoot 95% of all commercial ammo out there just fine . My twist calculator says you can shoot up to 73gr bullet out of the 1-9 twist . That is right on the line though. Remember it is possible to over spin a bullet . If your shooting cheaply made lighter bullets they are most likely not balanced very well . Over spinning those can cause the bullet to yaw at longer ranges and your accuracy will drop off quite a bit . That is a whole other thread that involves words I can't spell or prononce

Quote from BartB
Quote:
Every bullet has a bit of coning motion, or nutation about the trajectory axis. The more nutation a bullet has, the more drag it has. More rpm's caused by fast rifling twists causes more centrifugal forces that cause that nutation. Which means the BC will be less than those perfectly balanced ones. The center of that coning, or nutation, will be above the trajectory axis .
This can cause inconsistency's from shot to shot . You want the least amount of twist that will still get the job done . This is also more about long range competition shooting but it still rings true for all bullets
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Last edited by Metal god; August 11, 2013 at 08:49 PM.
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