Neck tension problem

[mikecr]

Sized brass is measuring .328 neck and a loaded bullet is .3295 on my micrometer. Yet I still do not have enough neck tension.

It's not the die, bushing, expander, or neck thickness, etc.
It's your annealing. You killed em

 

[Zero333]

I came across the same problem before with 300winmag Remington brass.

Sizing the brass AFTER annealing fixed the problem permanently

I quit using Rem brass all together due to one too many off center flash holes.

 

[Grimstod]

So I did some more checking and the brass does still have .001 of spring back just as it should. That means the annealing is ok. I talked to my gunsmith and he quickly figured it out. Because the bullets are seated so deep they are seated beyond the gas ring. Attached are some photo. As you can see the bullet shrinks a full .001in and leaving only .0005in of neck tension. The fix for this will be to throat it so the gas seal portion of the bullet is in the neck of the case. This also explains why I never had this problem when I was using a much shorter 168r Berger bullet.

 

[BenPerfected]

Good to hear that you figured this out, we all need a good coach.

 

[243winxb]

Here is how many I am loosing. the batch in the shell holder are good. The rest on the table are too loose.

Then why are some OK, and others are not? Were all at the same OAL?

 

[Webster]

I'm not an expert in the neck tension area but it seems to be a simple concept. I don't feel like reading and understanding any of the many replies, so excuse me on that point. You didn't mention if you have the ball expander in your bushing die. Doesn't it wipe out anything you accomplished with the bushing? You size with a specific bushing size then jerk a ball of some unknown diameter through the neck. Also it appears you are determining neck tension by measuring at the pressure ring at the back of the bullet? I would think a better measure of grip would be measured on the bearing surface. Not implying that the small pressure ring doesn't contribute. I think the pressure ring is only a few 10 thou over the bearing surface diameter on most bullets, so maybe it's meaningless. Maybe you have a big pressure ring?

 

[Ggmac]

I don't buy it , your neck length would surely grip the larger base of the bullet , as seen in your picture of it seated correctly next to the one pushed in by hand . Bergers aren't known for having a 2 diam bullet . You still need more tension ,or some of those case necks or bullets wouldn't be ok.
Since some were ok that tells me either those necks had thicker or more tension or the bullets were larger .

 

[Ggmac]

Get a mic that reads a couple more digits

 

[jlow]

Then why are some OK, and others are not? Were all at the same OAL?

Different work hardening, different spring back.

 

[Ggmac]

What size neck of a fired case ? Are all fired case necks the same OD fired ? Is all the brass sorted , number of firings , neck wall thickness , what size is the cases that held the bullets vs the soft seated bullets ?
I hope your smiths theory works , but something is going on because of the hit or miss case neck tension .

 

[Joe R]

You need to go to a .325 or even .324 bushing.

 

[Webster]

You need to go to a .325 or even .324 bushing.

Agree, It makes more sense to try a smaller bushing than ream out a longer throat. If you make the throat longer you may still have the same problem with excessive freebore.

 

[Joe R]

Grimstod said:
So I am working on a wildcat. This is a .308x54r Improved. Shoulder moved forward about .190 and a 40d shoulder. Barrel is a 308 and I am shooting 308 Berger 190gr VLD bullets.

I Just got in a new bushing for my custom made Redding Type S Die. Its a titanium .327 bushing. Sized brass is measuring .328 neck and a loaded bullet is .3295 on my micrometer. Yet I still do not have enough neck tension. This brass has only been fired twice. I can actually push the bullet in with my finger and the air pressure makes it pop back out.

I had the same problem with my .308 when I started thinning my necks down to .010. I'm using a Redding .326 bushing to size Lapua brass. I also anneal with a drill, I do it for 6 seconds. If you're annealing longer there will be less spring back so you will need a smaller (.325 or .324) bushing.

 

[Joe R]

By the way Grimstod, get a pin gauge to check your micrometer and calipers. I'm very familiar with the Berger 200 hybrids and my measuraments and experience don't jive with your mic's readings. It could also be that the 190's are different.



.

 

[Pumba]

Gimstod,

Yip I think you nailed the problem. I had the same with Sierra Pro Hunters. A bad batch I guess.

As little as 0.0005 thicker at the base will make your bullets slip through the neck if the base go past the neck sholder junction no matter what bushing size you use.

I use the batch bullets for fowlers now

 

[dkhunt14]

I don't buy it , your neck length would surely grip the larger base of the bullet , as seen in your picture of it seated correctly next to the one pushed in by hand . Bergers aren't known for having a 2 diam bullet . You still need more tension ,or some of those case necks or bullets wouldn't be ok.
Since some were ok that tells me either those necks had thicker or more tension or the bullets were larger .

Almost all bullets have a larger pressure ring then the shank. I have seen it go more then .005 on some lots. I agree you need a better micrometer. I use a friction thimble Mitutoyo that reads to 4 decimal places. It is really repeatable and will read the same measurement over 9 of ten times. I still think a little more size on the necks will help. If some stay and some slip there is also another problem someplace. Necks are not the same thickness, cases are not fired the same amount of times, Not quite enough tension, over annealed or not annealed the same . Matt

 

[Ggmac]

Yes bullets ,esp flat bases , have press ring , but not as large as what his mic is showing . Long ago 6.5 bullets made here had a 2 dia bullet . That bullet was near .001 different . Which is near what his Mic is showing the Bergers to be . I think , can't really tell with his mic.

 

[Grimstod]

I'm not an expert in the neck tension area but it seems to be a simple concept. I don't feel like reading and understanding any of the many replies, so excuse me on that point. You didn't mention if you have the ball expander in your bushing die. Doesn't it wipe out anything you accomplished with the bushing? You size with a specific bushing size then jerk a ball of some unknown diameter through the neck. Also it appears you are determining neck tension by measuring at the pressure ring at the back of the bullet? I would think a better measure of grip would be measured on the bearing surface. Not implying that the small pressure ring doesn't contribute. I think the pressure ring is only a few 10 thou over the bearing surface diameter on most bullets, so maybe it's meaningless. Maybe you have a big pressure ring?

I have been struggling with this for over a year now. Never had problems with short 168r Bergers or 155r Hornady. All the things recommended, annealing, bushing size, expander ball removal etc. have been tried multiple times.

 

[Grimstod]

Different work hardening, different spring back.

In the past I once loaded up a batch of these 190gr Bergers and sorted out all the loose ones. I took to the range only bullets that had enough tension. 2hrs later at the range as I was loading and shooting them I noticed that some were now loose. Could be the car ride jared them loose or the 40d temperature change. Not sure, but at any rate All of these are the same annealing batch. And they all have the same number of firings.

 

[Grimstod]

I had the same problem with my .308 when I started thinning my necks down to .010. I'm using a Redding .326 bushing to size Lapua brass. I also anneal with a drill, I do it for 6 seconds. If you're annealing longer there will be less spring back so you will need a smaller (.325 or .324) bushing.

View attachment 979595

What thickness did you turn the necks to? These are unturned but still thin at .0105