neck tension and 6mm rem.

[C. Collins]

1.) 6mm rem has a long neck for a 6mm round
2.) Can this long neck lead to neck tension/accuracy issues if not sized with a bushing sizer?
Thoughts?

The Chef ???

 

[Steve Blair]

Only the bullet engagement length is relevant, not the neck length. So, the answer is that neck tension can cause accuracy and consistency issues. I have three 6mm Remingtons and size all with full length bushing dies and anneal every three firings. The cases last reasonably well, considering the pressure. Two require turned necks and the third is a standard chamber. My loads use .002 tension for naked bullets and .003 for moly or hBN.

 

[C. Collins]

What type of brass do use? The problem I have is consistency issues. I'll put two on top of each other and a third of fourth will go wacko.

 

[Steve Blair]

I use both Winchester and Remington brass and have seen good and bad lots of both. One Win lot was more uniform than any I had ever seen. I tried to buy more of the same lot but was unsuccessful. I still have about 350 which are kept locked in one of the safes.

The usual prep regimen is:

1. inspect for defects - both will have occasional problems
2. weight sort
3. uniform flash holes - both manufacturers punch flash holes and leave internal burrs
4. trim to length and inside chamfer with VLD-style reamer
5. turn necks and outside chamfer


Winchester has a little better life than Remington, around 15 firings versus 12, at full pressure.

Take a look at the usual gun problems, too. Check your bedding, scope, bore condition, rest, bench technique, etc. Two of my 6mms need a firm hold to shoot well. The third weighs almost 20 pounds and can be held a little softer.

 

[C. Collins]

This was my first year of shooting 600 yards. I shot at the range 2-3 days a week. I worked alot on technique and it has improved quite a bit. With one rifle I can shoot groups in the .20 range at 100 yards. I know my technique at this time is solid. I am trying to work on the load to make it as solid as possible. My barrel has 750 - 800 rounds down it. The barrel is new this year. I have one load that will shoot well, but i get flyers. I continue to work on coal. I now a benchrest seater die on order to establish a uniform seating depth. That will only do so much is neck tension is whacked. I think? ???

 

[Steve Blair]

Are you using a standard sizing die? They often oversize the neck and the expander ball will introduce uniformity problems.

 

[40X Guy]

you could possibly buy some 7X57 Norma brass( parent case for 6MM Rem) and neck down to 6MM in 2 stages. I just did this after learning how thru this website and am having very good results with it. Very uniform brass and neck wall thickness. I was spending too much time sorting Win. brass and not getting the results I hoped for. I size neck after fireforming in my Ackley chamber exactly half way down neck to a .002 neck tension with a Redding S Match bushing die.

Frank

 

[Steve Blair]

Norma does make dimensionally uniform brass with some lots a little soft. Cost then becomes a factor as 6mm Winchester brass is $.35/case and Norma is ~$1/case. My experience with 6.5X55 from both manufacturers is that they have about equal life.

 

[C. Collins]

Only the bullet engagement length is relevant, not the neck length. So, the answer is that neck tension can cause accuracy and consistency issues. I have three 6mm Remingtons and size all with full length bushing dies and anneal every three firings. The cases last reasonably well, considering the pressure. Two require turned necks and the third is a standard chamber. My loads use .002 tension for naked bullets and .003 for moly or hBN.

So, where the bullet makes contact with the neck when using a standard sizing as opposed to a busing sizer can create increased tension in different areas on each cartridge which will then create accuracy issues. Is that about the jist of it?

 

[C. Collins]

What type of accuracy do you get with your 6mm and what load do you run? I have been trying the 107 smk cant get this to shoot well, 105 amax with reloader 17, 95 nbt with h4831, 105 ncc cant get this to shoot well. Its the vld hpbt bullets I have a hard time with.

 

[Steve Blair]

What is your twist and barrel length?

My 788 with standard chamber and 26" 9" twist shoots in the range of .5 or a little under. The 700 with 30" 7.5" twist shoots 115 DTAC and Bergers in .75-1.0 at 300 yards as wind allows. The 40XBR with 27" 8" twist will shoot the 95-108 bullets about the same as the 700.

I typically use Varget for 58 grain V-Max, H4350 or Reloder 19 for anything in the 80-108 range and Reloder 22, H4831 SC or IMR 7828 SSC for the 115s.

 

[C. Collins]

I have an 8 twist with a 27" barrel. The rifle is a savage with a douglas barrel from sharp shooter.