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308 HELP!


FireShooter

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I just built my first 308 gas gun. It's based off a DPMS platform. 18" JP enterprise bbl, 1:10. Sun devil receiver set, and all jp internals. I'm wanting some long range loads for this thing, so I loaded up 168gr BTHP over 46gr Varget to 2.800". It chrono at 2750 avg. but the groups are absolutely horrible. Am I pushing this round too fast or should this load be holding descent groups. I'm talking 4" groups at 100yds, and most of it is not me. Any ideas? I'm new to reloading so any help is awesome.

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Why would you start with the max load for that bullet? All loading mfgs suggest starting at 10% below minimum, which is 41gn for that bullet...so you should be starting at about 36-37gn, not 46.

I agree with striped1, get some match ammo and shoot some groups first, then start low and work up with your Varget/168 load, cronoing and shooting groups. That way you will find the optimum load easier and safer.

jj

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Back that charge off to 41.0gr and work up from there in .5gr increments. Fastest load is rarely the most accurate.

That said I just spent some time working up 308 loads for a friends M1A. Varget is my powder of choice but it did not perform well out of that semi auto.

Ramshot TAC performed best followed by IMR 4064.

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Thanks for the help. I tried some ladder testing, as well as some FGMM 168 and here's the results. Apparently I was loading the 308 way to hot for a gas gun. I slowed down the bullets and went up to a hornady 178gr hpbt match. The FGMM held at .6 moa and the 178 gr with 40.6 of varget held .45 moa with 1 flier. These are both 5 shot groups.

Edited by FireShooter
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FGGM is darn good ammo and it will be hard to beat that. DO NOT RELOAD the new federal brass, it is very very soft. Stay away from the Privi bullets, they don't shoot well. The 168 BTHP is an overall good bullet but its old technology. The new "better bullet" replacement would be the 175 BTHP, you can load it almost as fast and the ballistics are better, out of a 22" barrel you can keep them supersonic at 1000 yds, not so with the 168. With that said I would try some Sierra 150 BTHP match bullets if your shooting 500 or less, the profile is the same as 168's with a shorter shank; they will likely shoot as well with less recoil. This aside, I would error on the side of accuracy and function over attempting to hot-rod the .308 like in a .308 30" barrel palma gun. Your real velocities will be slightly less than what's in the books with your shorter barrel but you will likely not see a difference until you get past 500 yds.

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The 175's-178's are much better for long range but my gas gun didn't like them as well as the 168's- especially 168 Amax. You are definitely running them too hot with 46 Gr of Varget. I would stay under 45 grains. I am getting my best groups at anywhere from 43.5- 44.0 grains. About 2,650 fps

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