Neck tension for AR load?

[Tim K]

Been using a cheap Lee set of dies for my precision AR loading. It's given good results, but I'm thinking its time to get a set of Redding competition dies like I use for my bolt gun. The sizer will be a bushing die.

How much neck tension is typically used for gas guns? I assume more than is typical for a bolt gun.

[ray1970]

You need enough tension so that the bullet doesn't dislodge from the case and jamb into the lands when the bolt slams the round into the chamber.

Not the best answer, but its all I've got.

[Tim K]

I get it, Ray, I just need a number.

[ray1970]

I get it, Ray, I just need a number.

14.

[JM Ver. 2.0]

I get it, Ray, I just need a number.

42?

Sent from my teepee using smoke signals.

[Tim K]

You guys are not helping...

It's obviously 220 or 221.

[Great-Kazoo]

Mine mic out to 221 after being resized on a standard 223 sizing die. I put a barely noticeable crimp on then loaded rd. Say the seated bullet -neck is (without a mic an seated rd in front of me) measures .227 i set crimp to give me a .226 Again this is off the top of my head without any hard numbers to go off of.

[ray1970]

You guys are not helping...

It's obviously 220 or 221.

Sorry, Tim. I was just having some fun.

I honestly don't have a good answer since I don't do any precision stuff with my semi-autos.

Best of luck.

[Hoser]

Get a Dillon Carbide size die and run with it. Mine gives me about .004 - .005 tension depending on the age of the brass and how much spring back it has.

The Redding or Forster micrometer seat die is worth its weight in gold.

[IceAxe]

On my 6mm x 45, 2.5 thousandths is holding bullets up to 100 grains. That is with a trimmed neck thickness of 11 thousandths. Since these are 5.56 cases necked up, they are probably thinner than yours....you might be able to get away with less tension. I suspect a lot depends on your neck thickness and how heavy a bullet your going to use. I have noticed that switching to a nib carrier on one of my rifles has increased the bolt carrier speed so will probably limit that gun to the lighter bullets.