Too much neck tension

[jacq220]

I believe i am runing about .006 of neck tension. I was running about .002 but switched to lapua brass and dont have the correct bushing for my forester neck bushing bump die yet.

what negative effects might i see from this much neck tension?

 

[littlerascal56]

Re: Too much neck tension

I would say that you won't see much difference...if all your loads have the same .006 tension. Consistancy is the key.

I use my .332 Redding bushing for Winchester & Remington brass, and a .335 for Lapua, due to the thicker brass. This keeps everything at .003 tension.

I did assemble some loads at .006 for a frend with an AR-10T and he swears it was the most accurate ammo he ever shot thru a gas gun.

 

[jacq220]

Re: Too much neck tension

I am currently running a .334 bushing, and thinking about going w/ a .336 i think that should clear up the issue.

 

[Fuzzball]

Re: Too much neck tension

"what negative effects might i see from this much neck tension?"

It's higly likely run-out would greatly increase. And run-out is NOT good for accuracy.

 

[gcoulsey]

Re: Too much neck tension

i have read on here before, that actual neck tension caused by sizing, can never be more than .002-.003"...

the reason was something along the lines of,
due to the metal properties of the brass, its 'elasticity' can only provide .002-.003" of neck tension.

If you are sizing the brass down smaller than that with your die,
the bullet itself is simply sizing the neck back out again, but the neck tension is still no more than the brass's elasticity threshold. ??

Friction plays a part in the equation too, amount of bearing surface/wether the bullet is lubed or not etc etc.. but the actual neck tension itself from the sizing, isnt any different between a .007" reduction, and a .004" reduction. (all other things bieng equal!)

I may not have explained it as good as the guy that wrote the original article about it, but it made sense the way he said it lol!

i have no idea how true this is... but its a different way to look at your question!

*ducks for cover*

 

[jacq220]

Re: Too much neck tension

makes sence... long story short, what i was getting good groups w/ the day before started becoming "split groups" and the only thing that changed was the brass was fireformed (not new lapua brass) and resized w/ a forester bushing bump die which i have NOT had this problem before.

i started putting three in once hole, and two in another about .5 moa away. wondering if it was the load, or the nut. or the equipment.

 

[Clark]

Re: Too much neck tension

If you pull the bullet, measure the bullet diameter and the inside of the case neck with a bore gauge or pin gauge, the difference is the elastic limit of the brass. That is proportional to the real neck tension.

There is probably only .0015" difference on .308".

I am measuring .333" on my 308 loaded with commercial brass.
I am measuring .337-.340" on 308 loaded with military brass.
My die I sent out to get honed to .330".

Per the few measurement I just made, the .334" bushing would right for military brass, but would be too loose for commercial brass.

 

[JByrd]

Re: Too much neck tension

measure empty sized case , shoot for .002, reasonable , it will work