AR Sponsor
Posted: 4/28/2008 5:11:47 AM EDT
I have this idea to build a .260 AR around the 139 gr Scenar. I would like to push this at 2800 fps to match the drop of my .300 WSM load but I don't want to run a 26 inch barrel. I'm no ballistics genius here so..any help would be appreciated. I'm thinking a 22 inch barrel might be a good trade off between length/weight and FPS. The purpose of the rifle would be for fun and to provide sub .5 - .75 MOA out to 600 yards. Ballistic Explorer shows that the 123 gr scenar at 2850 also matches my .300 WSM load and wind drift seems to be VERY similar. My question is, first, general thoughts and second, how much FPS do I lose per inch of barrel here? Can I even get up to 2800 without building a musket? Thanks in advance.
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You'd need a 26" barrel to push a 139grn at 2800 fps... Now if you want to shoot the 123gr Lapua Scenar at 22", you might pull that off. It's got a BC of .547 and will probably be around 2800 fps. Click me! |
That is a tough one, since there are three different and distinct .308 AR series weapons out there. And none of them have interchangable parts. (except furniture etc.) Go with the one that gives you the most confidence for reliability, and accuracy. |
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I do have a 260 upper that JP built for me, two years ago. 22 inch. I was not able to get up to 2800 with 139's. You can get the 123 to 2800 or 2850. I ran into big preasure spikes until John Paul sent me down the right path for powder. I really love it now. 90TNT at about 3300 and the 123 at 2800 and the brass is reloadable. Jerry |
That's what I was afraid of. I knew the 139 would never make 2800fps out of a 26", but the 123 out of a 22" is definitely right on the border line...and doable. |
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