View Full Version : Neck tension for AR load?
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.
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.
I get it, Ray, I just need a number.
I get it, Ray, I just need a number.
14.
[Coffee]
JM Ver. 2.0
08-02-2013, 08:48
I get it, Ray, I just need a number.
42?
Sent from my teepee using smoke signals.
You guys are not helping...
It's obviously 220 or 221.
Great-Kazoo
08-02-2013, 09:15
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.
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.
[Beer]
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.
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.
Ray, I was kidding about the 220 or 221. It was a reference to the movie Mister Mom.
Hoser, it's really the seating die I like from Redding. I just assumed I needed a bushing die to cope with different wall thicknesses, but if a Dillon is the answer, that's what I'll do.
Jim, sounds like 0.006". Pretty close to what Hoser is seeing.
Get a crimp die if you're concerned.
Get a crimp die if you're concerned.
Bad for accuracy if your bullets dont have a cannalure and are not trimmed to the exact same OAL.
Am I screwing this up then? I load with just the tiniest visible crimp into the Cannelure. I take every 20th bullet and make sure I can't push it home by hand on bench. I don't seem to have any neck tension problems as the bullet shoot just fine. From my reading and studying my manual, 223 does not even necessarily need a crimp.
Zombie Steve
08-02-2013, 11:23
Much as I like the Redding dies, I just use a run-of-the-mill Lyman seating die. For shooting AR's, I'm just not that concerned with getting them to go from 3/4 moa to 1/2 moa. Are you just loading range blasters, or are you trying to get the same performance you get from that .260?
I did just test some Montana Golds with H4895 and they did prefer a light crimp into the cannelure. Not sure what bullet you're using.
Zombie Steve
08-02-2013, 11:25
Am I screwing this up then? I load with just the tiniest visible crimp into the Cannelure. I take every 20th bullet and make sure I can't push it home by hand on bench. I don't seem to have any neck tension problems as the bullet shoot just fine. From my reading and studying my manual, 223 does not even necessarily need a crimp.
Proof is in the pudding. Load some with and without a crimp. See what happens. I generally didn't crimp until I tested these MG's. It was a noticeable difference.
Unless your going to be sorting your brass by neck thickness or turning your necks i think a bushing die is over kill. From what i have read about crimping, it can improve or impair accuracy with some bullets in some guns. You would have to do the testing to see what works best in your gun. A general thought is to not crimp when looking for accuracy because it is one more area an inconsistency could be added to the round but sometimes it works.
Much as I like the Redding dies, I just use a run-of-the-mill Lyman seating die. For shooting AR's, I'm just not that concerned with getting them to go from 3/4 moa to 1/2 moa. Are you just loading range blasters, or are you trying to get the same performance you get from that .260?
I did just test some Montana Golds with H4895 and they did prefer a light crimp into the cannelure. Not sure what bullet you're using.
This is for my accuracy load. It shoots 1/4 moa pretty consistently, and even better on good days. I also load blaster ammo with the Hornady 55g bullet with cannelure. I cripmp those.
The bullet for my precision load is the Sierra 77g SMK, no cannelure.
Zombie Steve
08-02-2013, 13:11
It shoots 1/4 moa pretty consistently, and even better on good days.
Dude, you're done. [Beer]
I might get there one day if I build a free float upper. It's a pretty steep curve of diminishing returns.
I love the load. I'll likely be changing brass which may or may not have a different neck wall thickness. That's what got me started on the idea of a bushing die. Plus, I just love my micrometer seating dies. They are the best.
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