Most of the 140gr 6.5CM data I've seen the bullet slows down past 24" bbl length. Not sure why you'd want/need a barrel burner either (isn't thats what people pick 6mm/243 win for?) The stock Hornady 140 ELD-M load is already comparable ballistics to 300 win mag. I've shot 6.5CM out to 1200yds. You trying to "get meat" from the next state? Get someone to run your planned data through something like quickload. Would save a lot of experimenting.
On Tue, Jul 18, 2017 at 12:11 AM, Gene Heskett <[email protected]> wrote: > On Monday 17 July 2017 23:28:36 dave wrote: > > > On 07/17/2017 09:23 AM, Gene Heskett wrote: > > > On Monday 17 July 2017 11:08:19 andy pugh wrote: > > >> On 17 July 2017 at 15:42, Gene Heskett <[email protected]> wrote: > > >>> I saw that, and the long pipe gripped in the chuck with the huge > > >>> bearing so it all turned. The bearing is nice but $$$$$$ and not > > >>> needed if the tube is turned truly round. > > >> > > >> I imagine that a suitable bearing could be found that would not be > > >> all that expensive, especially as you could make the tool to suit > > >> the available bearing. > > >> http://www.ebay.com/itm/280920636178 looks like it could work. > > >> > > >> And I seem to recall that rifle barrels are very rarely circular. > > >> (though in the case of that rig in the video the real problem would > > >> be the gun carriage trunnions) > > > > > > In the case of a bolt action hunting rifle, that stuff is on the > > > action, barrels are generally turned smooth. Any taper is optional, > > > this one tapers to .82" at the muzzle. The only place where the > > > installed barrels rotation is important is a flat just wide enough > > > to clear the claw style extractor when the bolt is closed. Its often > > > filed by hand after the barrel is screwed in and an impression made > > > in some modeling clay to mark the boundaries by the bolt, with > > > extractor mounted, being pushed into the clay. Or a witness mark > > > made on the bottom. It could be cut with the right sized milling > > > tool. Remove it, file the flat, and reinstall to the same torque, > > > with a 4 or 5 foot handle on the action wrench. > > > > > > One thing I'd like to see some attention paid to, is designing a > > > taper that doesn't have a natural resonant frequency. But most just > > > turn for pretty, or hitting a max allowable weight. Such barrels > > > tend to be quite picky about the load for best accuracy, often found > > > by loading in slowly increasing charges, and shooting to see the > > > movement on target as the charge is increased. The most accurate > > > load will generally correspond to the widest swing of the string on > > > the target because at the peak of the widest string, the barrel is > > > moving the slowest as it peaks at the swing point at the instant the > > > bullet leaves the muzzle. At that point, a small variation in charge > > > or ignition has the least effect on the impact point. Change the > > > load so its at the mid-point of that vibration, perhaps a 2% change, > > > and it becomes much more sensitive to a .1% change in the load > > > because that movement swing is at the highest velocity. > > > > > > Bug hole guns are a whole science in themselves. So are the > > > shooters who can make them perform. At my age and eyesight today, I > > > am long past my peak. So I cheat with ever more powerfull glass > > > sights. I can recall a shooter on an adjacent bench in 1978, calling > > > my attention to a fly sitting on the corner of my target, 100 meters > > > out. I moved a few grains of sand in the bags and said "do you mean > > > that one?" as my rifle spoke. He said I missed, so we bet a 6 pack > > > and walked out to look at the target. The bullethole had > > > bloodstained edges. ;-) But that was 39 years ago. And I had a Bud > > > to wash down dinner that evening. > > > > > > Cheers, Gene Heskett > > > > Gene, > > I've seen strips of pop cans used as a buffer (static) between > > the chuck jaws and a barrel. > > More than likely a steel barrel, where any traces of alu would be > polished away, and then hot salts blued. About the only thing I can do > to this SS is improve the polish, which for a meat collector, is a bad > show. Ideal would be to cork it up, and using a fine grit, sandblast it > to give the surface some "tooth", and paint it, using an assortment of > flat camo colors. 100% coverage being the most important attribute. > > > There are also some steady-rests done with hydraulics so that there is > > always a dampening > > load on the barrel but not binding. Good, fast, cheap: pick any two. > > Some try to dampen the barrel by bedding so there is upward pressure out > at the forearm tip constituting a dampening friction. But you have to > keep weather records so you only take it out of the rack to shoot it on > days when the weather has been just so, for the last week. :( I want it > to shoot well anytime I pull it out of the cabinet, weather being the > least of my worries unless its too cold for my diabetic feet. > > I bought a couple boxes of Hornady's new ELD-X 140 gr bullets, and 250 > new Starline cases so should have stuff to load it on the shelf right > now. Downright sexy, with a G1 BC of about .620. The only place that > carries a warning is the box itself which has a notice of 8 turns per > inch minimum, and probably would be 700 meters out before any yaw > settled if sent out of a 9" twist barrel. The chrono will tell me if I > can get 3000 fps out of a 30 inch barrel. Most data stops at 2900, in a > 24" barrel. > > > Dave > > > > ---------------------------------------------------------------------- > >-------- Check out the vibrant tech community on one of the world's > > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
