loose neck

[686]

i am shooting a 6mmbr. .272 neck, size .269 . loading 105 amax. after 5-6 loads i have a few hulls that the bullet pushes in the neck by hand. are the necks getting hard and springing back after sizing? is it time to anneal? i am not working the neck much. i have .002 bullet tension, .002 expanion, and .004 resized. when you use a temp. stick mark on the neck, do you put it on every one or just a few to keep you going correct with your time and temp. ?

 

[GermanS1]

When you say "size .269" do you mean you're using a .269" bushing? If so, you're barely getting any neck tension at all and that would explain the problem. You most likely need a .267" bushing.

I have a short article about neck tension and bushing sizes here (http://riflemansjournal.blogspot.com/2009/10/reloading-neck-tension.html) that may be helpful.

 

[686]

it is a .269 bushing and from sized brass to brass with the bullet seated i have .002 tension. that is with new-3-4 fired. every thinf works good. at 5-6 fired the necks are looser in side after sizing.

 

[GermanS1]

That makes your loaded rounds 0.271" at the neck, thicker than what I've seen before on 6BR brass, but that may well be. You may simply need to go to a smaller bushing after a few firings, that happens with some lots of brass.

 

[RonAKA]

I would try annealing first, and if that does not solve the issue, then you need to go for a smaller bushing. Annealing should reduce springback a little. I'm currently using a 0.267" and get about 0.001" fit. The brass springs back to 0.268, and loaded rounds are 0.269.

The last annealing I did, I used a 800 deg F tempilstick. It was kind of a pain. The next batch I am going to use the tempilstick but do the annealing in very low light -- just light enough to see what I am doing. You need to get the neck and shoulder just to 800 F for a few seconds, and then dump in water. I believe in low light this should just have a dull red glow. My thoughts are to use the tempilstick to train my eye to recognize the color of 800 F. It is too slow and painful to use the tempilstick on every case. Will practice with some trash brass before trying the Lapua.

 

[6BRinNZ]

Hi 686,

I have the same issue after 4 firings. In my situation I am confident that it is the brass that is hardened. I am going to go down the annealing track to resolve, the jury is out for me as to which is better (easier) - chasing neck tension with bushings or just annealing.

 

[4xforfun]

1: Load a dummy that will actualy hold a bullet.

2: Measure the loaded round......is it .269, 268, ...what is it.

3: Only after you get that measurment can you try and figure out your actual neck tension. Or you can measure your neck thickness (.013, .0135, .014,...whatever it is) double it, and add the bullet diameter....in this case... .243. So .243 +.013 + .013 = .269. It is just easier to measure a couple of loaded rounds.

4: If your loaded rounds are .269 you need a .267 bushing to get .002 neck tension.

Simple as that.