Neck Tension after 6 reloads

[n8ess]

I was reloading some 6mm Br lapua brass last night and noticed 2 of the necks out of a batch of 50 were loose when seating the bullet, at first I thought I must have missed the cases when resizing. I fired the primer and resized them but the neck tension remained the same. I do turn my necks despite having a standard chamber but only remove 75% of the O/D.

 

I am assuming the brass has thinned due to the case stretching, I have never had to trim the cases as such, the case length has remained in spec with de-burring alone. My point is should I call it day on the brass and buy new. I have read on that you should easily get up to 10 reloads from lapua brass in 6mm BR.

 

Cheers

 

Neil

[Andrew]

You really remove 75% of the OD?? That would be a problem.~Andrew

[n8ess]

You really remove 75% of the OD?? That would be a problem.~Andrew

 

I Haven't quite explained that very well. I turn the necks untill I have about 25% of the brass untouched.

 

Cheers

 

Neil

[Elwood]

If the other 48 are fine then use them and bin the two that are troublesome. Or perhaps anneal the two rogue cases and see if that makes a difference.

 

Just for the sake of science, if you don't anneal then send them to me and I will do them for you.

[n8ess]

If the other 48 are fine then use them and bin the two that are troublesome. Or perhaps anneal the two rogue cases and see if that makes a difference.

 

Just for the sake of science, if you don't anneal then send them to me and I will do them for you.

 

Thanks Elwood, I might take you up on your offer, am I right in thinking annealing will return the case hardness of the brass back to near it's original state, I didn't think this would effect the O/D? or is it that the brass becomes soft and no longer holds its position when re-sized?

 

Cheers

 

Neil

[Elwood]

As I understand it, the brass gets work hardened and losses its spring, so as the expander ball comes back up through the neck the neck will stay at that diameter, where as ideally you would want the brass to spring back a little.

 

If I'm talking ###### someone please feel free to correct me

 

Have you measured the outside and inside diameter of the two cases and compared them against the other 48?

[Alycidon]

I am running a tight fitted neck on my 20BR and have a series of neck bushes made up in .0005 increments together with a series of stepped neck id gauges and hand cutters.

 

After initial resize and tumble case necks are inside hand reamed then checked with the stepped gauge. Any oversize are resized with the next bush down and the process is repeated. That normally gets all the necks the same od although just occasionally an odd case requires a third resize.

 

The problem is coming from brass spring back, the odd ones are springing back more that the others.

 

A

[Redfox]

As the brass is worked it does harden a little each time, it actually will spring back more when harder rather than less. I would never turn the necks more than 50% or a fraction under for a standard neck. I only neck turn when the brass is new to get an even thickness all round and if you think about it 50% or less will do that for you.

Over the years and having access to accurate equipment to do annealing, I have done it on different makes of case and had various results, certainly if you over do the annealing the cases will appear tight on the bullet on insertion but as they are actually too soft they dont hold the bullet well and are not consistent from one to another. The biggest factor is the type of brass used in the case, U made cases are certainly different to european cases and tend to be slightly harder, the Norma and Lapua and RWS brass has a slightly higher copper content and tends to be less hard. Norma did some tests on their cases and with correct minimum needed sizing got 80 plus reloads before neck splitting occured, I have had 20 plus out of both Rem and Winchester brass and a few more out of Federal brass.

Having fiddled about and knowing how hard it is to anneal accurately and only in the right area, I now just use the cases until I know they are going off and then scrap them, I have less variable accuracy issues and keeping them in batches of up to 50, I know what number of reloads they have had so how long they have to go and certianly no loss of accuracy with any particular round. Careful prep when new, care in selecting components and in the reloading process has given me far better returns than any other item in reloading.

Now I need to find the formula to offset getting old!

Redfox

P.S two duff ones is excellent I usually find several in any batch that do their own thing, we dont live in a perfect world and if every case was perfect and identical we couldnt afford them.

[baldie]

You've surprised me there Redfox, about federal brass ? its always had a bad reputation ?

I have thousands of .308 once fired federal cases [police]

Some testing is in order methinks.

[Redfox]

I do think it depends on the calibre, I have loads of Fed 222 and can easily get 25+ reloads out of them but it isnt exactly working hard in those, I dont get as many out of 243 or 22-250 as it gets well stretched in those Even Norma and Lapua dont do as many in those cals. It is as you say a matter of trying them out.

Redfox