Neck tension

[KeithR41]

Why sm I getting inconsistent neck tension with R-P .260 brass. My brass is all mixed between 4 and 5 firings, maybe even 6. I annealed 20 rounds tonight the FL sized in an RCBS sizer. When seating bullets I found a very noticable difference in neck tension with the brass.

Am I missing something obvious?

41

 

[The Mechanic]

Re: Neck tension

Where to start. Do you have a good chamfer? How clean is the inside of the neck? Did you trim? Are you crimping the neck any? (long case). Do you have a compressed load? Can you take a few of the annealed cases and crush the necks to find out if the tension is the same? Maybe over or under annealing.

 

[Victor N TN]

Re: Neck tension

Have you checked the wall thickness on any of your brass? Brass from different makers or even different lots can have different wall thicknesses on the case necks. Check that first. That will have a great impact on neck tension.

 

[KeithR41]

Re: Neck tension

All the brass is trimmed and chamfered. The load is not compressed but I have not checked the thickness. I've never turned my necks. That sounds like it might be the best place to start.

Keithr41

 

[KeithR41]

Re: Neck tension

I also tried squeezing a couple necks with pliers. They felt like same as a new one.

 

[427Cobra]

Re: Neck tension

The anneald brass should what appears like more NT, this is because it is soft again and has held it's shape, unannealed brass is springie and expands slightly giving the appearance of less NT

 

[BK7saum]

Re: Neck tension

What process did you use for annealing? Sounds like some cases are softer than others. I doubt neck thickness is your problem. If you haven't experienced this before with this batch of brass, then neck thickness shouldn't be your problem.

I keep my brass sorted by headstamp and also lot number (meaning if I buy 100 lapua brass now and more later, the first 100 will always stay together and not get mixed with any later batches I buy). This really isn't an issue with Lapua, but I've noticed differences in case weight from batch to batch from Win, RP, Fed, etc.

If you were dealing with mixed RP, Win, and Fed, It might be possible that the annealed brass from each manufacturer exhibited different "springyness when annealed. Since all RP, probably not the problem.

Doublecheck your annealing process.

 

[Jeffvn]

Re: Neck tension

Your used brass is work hardened. Assuming you are doing your annealing properly, and not overcooking the brass, your annealed brass is now returned to it prior state. It will feel different meaning have a different seating pressure to seat the bullets from the work hardened brass.

I anneal my F-Class and tactical 7WSM brass every 2 firings, and can tell the difference in seating pressure between the two. If you are anal like me you will also have felt a difference in effort required to resizing the brass after annealing it.

JeffVN