Neck Tension for AR-15

[billmo]

Been doing a lot of reading about neck tension for these things.
I am single feeding for now off of the sled. Is .002 enough tension or should I get a smaller bushing. My loaded round neck diameter is .247 with the IMG brass and I have a .245 bushing in my die. It seemed fine when I initially loaded those first 25 rds. of new unfired brass. Any comments guys? Thanks, Bill

 

[Spotcheck_Billy]

Bill,
Your neck tension sounds ok, but Redding now recommends a bushing only .001" smaller than loaded neck diameter rather than their old .002" recommendation. It would probably be best for you to experiment with it, but if your results are good now you might not notice any improvement at all.

My method loading for my AR's is not to use a neck bushing at all when loading new unfired brass. Instead I just run the new cases through a Sinclair expander body with the .224 expander mandrel. This ensures that the neck is round and concentric with the case body and gives what I find to be perfect neck tension. I then go to the neck bushing on the fired cases. Just my way of doing things, and I'm sure that there's plenty of other methods that will also work well.

 

[billmo]

Thanks Billy for the info. Are you using the .001 under or .002 on your fired brass?

 

[Spotcheck_Billy]

Bill,
I'm using a .002" bushing and Winchester brass. I just haven't got around to ordering a .001" smaller bushing for my .223's yet, been too busy messing around with my 6.5-284 and 6.5x47L this summer.

 

[Asa_Yam]

NOTICE: An AR-15 is a semi-auto rifle, and not a benchrest gun!

Going too light on neck tension is a potential disaster if the bullet telescopes into the case, or jumps forward into the rifle. This is made worse by work hardening of the case neck - over time, neck tension will decrease unless either a smaller bushing is used, or the case necks are annealed.

Brass is cheap. Bushings are cheap. Eye and finger repair/replacement surgery is not cheap.

 

[Spotcheck_Billy]

Asa Yam,
That is an excellent observation, and the warning should be well heeded, especially for the uninitiated.

In this particular case I was addressing a specific question. Bill is single loading from a lead sled. Yes, the shock of the bolt carrier closing can move the bullet if it's not held in the case with adequate tension but I would think that Bill knows what signs to watch out for when it comes to insufficient neck tension. The first test would be how it feels when seating the bullet with the new bushing as compared to the feel when seating with the tighter neck tension that was previously successful. If the neck tension is too light you can generally feel it. The next test would be to push the bullet tip against the loading bench to see if the round gets shorter. If you can move the bullet with relative ease the neck tension is too light for the AR15.

There's a very informative discussion about neck tension in regards to loading for the AR that can be found in Glen Zediker's book " The Competitive AR15" starting on p.198 of the Handloading chapter. This book is a must have for anyone loading for the AR15, IMO.

 

[billmo]

So should I go to a tighter neck bushing immediately or swap it out before I reload more than 2 or 3 times? Thanks, Bill

 

[billmo]

When I loaded the first 25 new unfired cases the bullet fit was tight. I have not loaded those 25 but I will check them out really good when I do get around to loading them. Thanks for all your comments and suggestions. It is good to have a group of guys who have this kind of knowledge.

 

[Spotcheck_Billy]

So should I go to a tighter neck bushing immediately or swap it out before I reload more than 2 or 3 times? Thanks, Bill

Bill,
You'll just have to experiment to see what works in your particular circumstance. Generally, I settle on what bushing Im going to use when the brass is still fresh and flexible. After the brass has been shot several times I go to a bushing that's .001" tighter, then finally go to a bushing that's another .001" tighter than that when the cases are pretty old.

That's just how I do things, but you know what opinions are like!

 

[billmo]

That's my train of thoughts also. I will keep a close eye on the tension and adjust accordingly.

 

[ronemus]

A case neck will expand elastically,will return to its original diameter) 0.0015-0.002", and beyond that it will permanently enlarge to some degree; you can't increase bullet pull by making the neck smaller past a certain point. However, a smaller neck will increase the bullet seating force, essentially using the bullet as an expander. I use an expander of full bullet diameter to obtain maximum bullet pull while requiring no more seating force than necessary. My sizing dies are dimensioned so that with neck turned brass the necks are sized only a 0.001-2" below final diameter, so the necks aren't overworked; the minimal expansion then makes the cases uniform and mitigates the "evil" effects of using an expander.

 

[billmo]

ronemus, are you loading for an AR-15 with this method? Thanks, Bill

 

[ronemus]

Yes Bill, I'm loading for an AR-15 spacegun,for NRA Highpower competition) in .223. I use the same method for my .284 bolt gun as well.

 

[Spotcheck_Billy]

Bill, ronemus:

I never use an expander. I thought that fact was naturally assumed, but you know what they say about that word I remove the expander and put the dummy button that comes with the Redding Type S dies on the stem and go with that method. As I posted earlier, I use the Sinclair expander die and mandrel when I need to expand the neck or straighten it out.

 

[billmo]

Well, I ordered the floating carbide button for my Bushing die and installed it. But I will take it out and resize without it if you think that will work best. Thanks, Bill