Neck tension? Crimp?

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13 years 2 months ago #27535 by Scorobe2916
Neck tension? Crimp? was created by Scorobe2916
New to the AR-10 format guns, but have owned several AR-15 rifles, anyway. Was interested to know what the consensus is on neck tension for .308 Win out of an AR-10 or crimp? I only run .001 neck tension in my BR gun and I am pretty sure I couldn't get away with that little neck tension, I also have my bullets seated .005 into the lands which probably wouldn't work either, in testing seating depths in the AR-10 I have found the best spot to seat my bullets are .09'off lands woooo way off , but that's where it likes them. Any info on what you all are running for neck tension and what works for you would be appreciated, better than starting blind.
PS measured my chamber dimensions at 2.035, trim length in the book is 2.005, any body think I would have any problems as long as I kept it under 2.025, pretty sure it's a sloppy chamber.

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13 years 2 months ago - 13 years 2 months ago #27550 by bipe215
Replied by bipe215 on topic Neck tension? Crimp?
I don't crimp any rifle loads. I've checked chambered rounds for movement in my AR-10 and found none. There are more experienced reloaders here than I though, I'm sure someone will chime in. Welcome to the forum.

Steve
Last edit: 13 years 2 months ago by bipe215.

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13 years 2 months ago #27556 by LebbenB
Replied by LebbenB on topic Neck tension? Crimp?
I use a Lee crimp die, so there's no way to measure the amount of neck tension with it. My personal preference is a light to moderate crimp for all my gas guns if nothing more than to mitigate potential bullet set back

You should be good to go at 2.025.

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13 years 2 months ago #27561 by Scorobe2916
Replied by Scorobe2916 on topic Neck tension? Crimp?
I figure some loading techniques might relate but being an auto the first priority has to be that it will cycle. Crimping seams like the safe thing to do, getting a bullet jammed could be a recipe for disaster. Have you noticed more pressure signs in the guns you crimp? Or any deformation in the bullet? Suppose the pressures you would get from crimping are probably far less than I would get jamming the bullets into the rifling in a bolt gun. Anyone out there have any solid proof that crimping would be detrimental to accuracy? Ahhh never mind I should test for myself, I'm sure crimp vs no crimp is one of those things that's 50/50. Thing is I can set up my die to run .012 tension but I am not sure that has the same holding power as a crimp???????
Thanks for the input

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13 years 2 months ago #27563 by LebbenB
Replied by LebbenB on topic Neck tension? Crimp?
I've gotten no over-pressure signs from any of my gas guns, but then I stay away from max charges as well as compressed loads.

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13 years 2 months ago #27595 by LebbenB
Replied by LebbenB on topic Neck tension? Crimp?

Thing is I can set up my die to run .012 tension but I am not sure that has the same holding power as a crimp???????

Make some dummy rounds - 4 or 5 with a crimp and 4 or 5 with high neck tension. Then hand cycle them and check for bullet set back. That should give you an idea of what direction to go.
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13 years 2 months ago #27606 by Scorobe2916
Replied by Scorobe2916 on topic Neck tension? Crimp?
Finding the perfect load can be like looking for a needle in a hay stack, and what is with only getting 2550 fps out of an AR, my F-class single shot 308 Win is getting 3000fps is that normal to be that much slower? Granted I haven't been using more than 42 gr of Varget in LC Brass, in my AR . Would adjustable gas block help?
I love new toys, and it seams like the AR 10 platform has as many aftermarket gizmos as AR-15.
Not really sure which ones help and which don't?

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13 years 2 months ago #27609 by LebbenB
Replied by LebbenB on topic Neck tension? Crimp?

...what is with only getting 2550 fps out of an AR

What length of barrel do you have on your AR10 and what weight/type of bullet(s) are you using?

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13 years 2 months ago #27617 by Scorobe2916
Replied by Scorobe2916 on topic Neck tension? Crimp?
24" 1-10 twist shooting a 168 SMK, my bolt gun has a 26" tube shooting the same bullet w/Varget.Would like to try and keep it from going subsonic Before 800 yds. What kind of speeds are you getting?
I would assume its going to be slower but almost 500fps seams like a lot? Again I am new to this AR-10 thing, and maybe that's just what I'm going to get as far as fps:)

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13 years 2 months ago #27618 by LebbenB
Replied by LebbenB on topic Neck tension? Crimp?
2550 is a bit unusual out of a 24" w/168 SMKs. With a 20" barrel shooting 175gr SMK/BH OTM I'm getting just under 2600, with the round transitioning to sub-sonic ~800m or so. FGMM 168s are 2650 at the muzzle out of a 20" as a point of reference.

Assuming 60 FPS per inch of barrel, theoretically you should be close to 2800 FPS.
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