Neck tension question

jmccracken1214

jmccracken1214

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Using Hornady custom grade dies.

I notice on some of my brass, when seating bullets, some go in pretty tight (hard to seat) and some (not many) go in pretty loose feeling. Most seem consistent, Just wondering what causes this? Is there a solution?
 
Have you checked the thickness of the necks between the 2 groups?
Tight and lose fitting brass?
 
The sizing die reduces the outside diameter of the case smaller than it should be. The expanding plug increases the inside diameter of the case to what it should be. This works very nicely for most cases that have different thicknesses. I have run into cases in which the case wall evidently was so thin, however, that the sizing die could not size the case to be small enough for the expander plug to do anything except go in and out of the case without expanding the case at all since the inside diameter was already too big.
 
Neck tension is a key to precision loading. I have measured Lapua brass and found 0.001+ difference in neck thickness when measure at 120 degree increments. The picture below is of neck turned Lapua brass and it clearly shows the inconsistency. That said, this is Lapua brass, on Hornady brass I have found similar results and on Federal, well I don't load it anymore.

The expander ball should set the internal diameter of the neck, properly and consistently, but if the neck thickness varies like the picture below, well the results cannot be more consistent than the product you start with.

Laupua neck turned.jpg
 
Slacker said:
This is why folks turn necks.
Basically, a tiny lathe.
Click to expand...
I have had very good results turning necks to achieve consistent neck tension when loading some rifle rounds. I did, however, get a little too enthusiastic when I first got my neck-turning gear and took enough metal off the necks of some 30/06 cases that I could not get any neck tension with the dies I was using.
 
Since we are talking about neck tension, how much tension should you have when you insert the bullet and is compressing/crimping the neck around it? I have a Lee die set for 30-06 with the collar thingie and have no idea of how much I should crank it down.
 
dalek said:
Since we are talking about neck tension, how much tension should you have when you insert the bullet and is compressing/crimping the neck around it? I have a Lee die set for 30-06 with the collar thingie and have no idea of how much I should crank it down.
Click to expand...
Getting a little off topic, but...

IMHO, if it is for a bolt action rifle, don't crimp. If it is for semi-auto, then possibly crimp, but no more than is necessary to prevent bullet setback or bullet jump. Take a test round (no powder or primer) and seat the bullet. Measure and record the OAL. Then chamber the round several times, letting the bolt slam the round into the chamber. Take the round out and measure the OAL to see if it has changed. If it has change more than maybe 0.005"-0.010", then you may need to crimp. Start out with just a slight crimp and keep repeating the process until the bullet does not move. The amount of crimp needed may vary depending on the brass and the gun.
 
dalek said:
Since we are talking about neck tension, how much tension should you have when you insert the bullet and is compressing/crimping the neck around it? I have a Lee die set for 30-06 with the collar thingie and have no idea of how much I should crank it down.
Click to expand...

They say your necks should be 1 to 2 thousands under bullet size for bolt action, and 3 to 4 for gas guns.

Unless all your brass has the same neck wall thickness, and you aneal every time, it's kinda hard to get them all the same.

For testing, I have resized brass that was shot 5 to 6 times that wasn't annealed, and it sprung back open, the tension wasn't even in the 20 or so I tested, even squeezing them with 5 thousands under bushing wasn't doing it, same brass resized like butter after annealing, and held more evenly across all of them.
 
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I load 77gr SMKs for hipower. Lately I've noticed inconsistent feel when seating them. The case necks seemed ok so I checked the bullets. The last bulk box(500) I bought contains quite a variation in base configuration. Some of the boat tail portion of the bullets seem to have almost a concave shape to them, where others have a constant slope to them. The concave base makes for a harder press on the handle to seat them, but I haven't seen any difference in performance.
 
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Boattail. The tapered shape of the base is inconsistent. I weighed about a dozen a few nights ago and they varied a total of about .4 gr where usually it's only about .1gr
 
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