6.5creedmoor neck tension

[pby5cat]

I have been reloading for my semi-auto DPMS pattern AR, 24in Fulton Armory. when i need to pull a bullet, it takes 10 wood deforming strikes on the hammer. I am also having increasing ejector swipes. I am using the Hornady Custom Grade New Dimension 2-Die Set 6.5 Creedmoor and hornady brass fired many times in my rifle. I have the seater die set so no crimp is applied to the shell. I know i need some tension/crimp for AR mags and BCG slaming the rounds around.

bullet diameter is 0.264
my expander in my die measures 0.2615
A many times fired case after full length resized.
If i measure the outside of the neck and subtract the neck wall thickness i get 0.260
If i measure the inside of the neck directly i get 0.259

So my bullet seems to be larger then my case by a lot, any suggestions on fixing this?
Will decreasing the neck tension reduce the ejecter swipes?

 

[mdmp5]

What is your neck diameter of a loaded round? Check the diameter before and after you seat a bullet.

The ejector wipes are most likely not from neck tension. Reduce your load by a half a grain

 

[OF&B]

I have been reloading for my semi-auto DPMS pattern AR, 24in Fulton Armory. when i need to pull a bullet, it takes 10 wood deforming strikes on the hammer. I am also having increasing ejector swipes. I am using the Hornady Custom Grade New Dimension 2-Die Set 6.5 Creedmoor and hornady brass fired many times in my rifle. I have the seater die set so no crimp is applied to the shell. I know i need some tension/crimp for AR mags and BCG slaming the rounds around.

bullet diameter is 0.264
my expander in my die measures 0.2615
A many times fired case after full length resized.
If i measure the outside of the neck and subtract the neck wall thickness i get 0.260
If i measure the inside of the neck directly i get 0.259

So my bullet seems to be larger then my case by a lot, any suggestions on fixing this?
Will decreasing the neck tension reduce the ejecter swipes?

Reducing the neck tension probably won't reduce the ejector swipes much if at all.

If the load is within reason, an adjustable gas block probably will. As the gun gets rounds through it and cycles easier, sometimes the bolt timing needs to be slowed down. The ejector mark is from the bolt starting to open too early rather than over pressure.

As the brass ages, it gets harder and will spring back more. Since the last operation is the expander ball, the sized neck diameter gets a little smaller with each loading. If you were using bushing dies, the last operation would be reducing the neck diameter and it would be getting larger as the cases aged. A smaller bushing would solve the problem. Annealing the brass will put you back to square 1 and reduce the neck tension with your setup.

Measuring a case neck before and after you load it is the most direct way to get the neck tension. .003"-.004" is considered ideal for auto loaders. I've lived with as much as .008" with thick necked brass and a Dillon trim die. When the bullets were knocked out of the cases, the remaining neck tension was only .0015"-.002". Pretty much just the spring back. You might try that drill and see what you come up with. If you're not shaving jacket off the bullet or setting case shoulders back when the bullets are seated and the load isn't internet hot, the numbers you posted should not be causing your problem.

 

[pby5cat]

So before seating a bullet the outer diameter of the neck was 0.288. After seating the bullet, the neck is 0.291.

I had to pull 3 rounds, 1 bullet had the jacket striped off on one side, the second one had scrape marks on the bullet. the last bullet was fine.

I have noticed when making my last batch of rounds, that there would be copper building up where the neck meets the bullet. I am going to assume that if i pulled that bullet, copper will be stripped off the bullet.

 

[OF&B]

So before seating a bullet the outer diameter of the neck was 0.288. After seating the bullet, the neck is 0.291.

I had to pull 3 rounds, 1 bullet had the jacket striped off on one side, the second one had scrape marks on the bullet. the last bullet was fine.

I have noticed when making my last batch of rounds, that there would be copper building up where the neck meets the bullet. I am going to assume that if i pulled that bullet, copper will be stripped off the bullet.

0.003" is good for neck tension, that shouldn't be your pressure problem. Chamfering the case mouths will get rid of the bullet shaving.

A 24" 6.5 with a standard length gas system is going to have higher port pressure and longer dwell time than a 20" 308. Only so much can be covered up with port size, and the manufacturer will err on the side of all guns always cycling. If you're getting ejector swipes from loads that didn't do it before, it's probably the bolt breaking in and opening faster. An adjustable gas block will enable you to adjust for that.

 

[Rob01]

So before seating a bullet the outer diameter of the neck was 0.288. After seating the bullet, the neck is 0.291.

I had to pull 3 rounds, 1 bullet had the jacket striped off on one side, the second one had scrape marks on the bullet. the last bullet was fine.

I have noticed when making my last batch of rounds, that there would be copper building up where the neck meets the bullet. I am going to assume that if i pulled that bullet, copper will be stripped off the bullet.

That's .003" of neck tension and is fine. Wouldn't cause any pressure. With some auto loaders you will get swipes from the ejector no matter what load. I had a rifle I got that with any load I put it. Just the nature of the beast. If primers aren't flattening out or other issues showing up then I wouldn't worry if using a safe load.

Chamfer the case mouths as mentioned to provide a smoother path for the bullet to enter case and take off any burrs.

 

[LV 426]

My Hornady Custom Grade New Dimension 2- Die set # 546289.
Expander is 0.2630. Inside neck is 0.2620 Hornady Brass. Hmmm.

 

[LV 426]

Before seating bullet outer die. Is 0.2880.
After seating bullet neck is 0.2895 ... 140 hornady and 142 Smk.