Neck Tension questions

[dkhunt14]

My theory on it is it evens out the chamber pressure. I think it holds the bullet a hair longer and raises the pressure slightly. I have no way of testing this and just is my assumption. That is also probably dependent upon where the bullet is seated in reference to the rifling. It might help more if jammed or maybe jumped. Not sure about that. I just know the paper says something is changing. Matt

 

[mike a]

Its Neck Squeeze. That's what the bushing does. .002 Neck Squeeze

 

[jlow]

So if both seating depth and neck tension works through affecting barrel time as a common path/mechanism, are there really any differences in terms of their effect on precision? Certainly one can accept differences between the two on the shape of the pressure curve and the mechanism of how they affect it, but if both are still doing their magic on precision via barrel time, it is hard to prescribe a difference on precision?

 

[noload]

I don't know about u guys, but I'm going to set up some test loads with more neck tension.

 

[Dusty Stevens]

I loaded up some the other day on a .262nk that had so many holds it had an hourglass neck. N133 likes a lot of holds and its hard to get it with the thin necks

 

[Dusty Stevens]

Ferdinand Guffey said:

 

[Tozguy]

Now hold on for a minute here, you shouldn't be smoking while reloading!

 

[Patch700]

^^ Lol^^

Seriously though , has anyone ever noticed there is a peak with regards to increasing bullet grip?

In several 6.5 calibers i have played with as little as .001" fit and continued up to the point where the neck was sized in two steps to where it would in theory have .010" fit... And what i found was that at a certain point you plateau and the difference between .006" and .010" was not noticable.
In a nutshell , if you had a case mouth that had an id of .2380" and ran it up onto a .2630" mandrel would it have more grip than a bullet that was seated and measured .2430" ?? Probably not as the brass is expanding in both cases.

 

[dkhunt14]

^^ Lol^^

Seriously though , has anyone ever noticed there is a peak with regards to increasing bullet grip?

In several 6.5 calibers i have played with as little as .001" fit and continued up to the point where the neck was sized in two steps to where it would in theory have .010" fit... And what i found was that at a certain point you plateau and the difference between .006" and .010" was not noticable.
In a nutshell , if you had a case mouth that had an id of .2380" and ran it up onto a .2630" mandrel would it have more grip than a bullet that was seated and measured .2430" ?? Probably not as the brass is expanding in both cases.

Yes I believe there is a Peak. I think the gain per .001 of tighter works out less per .001 because of expansion. The other thing that is happening maybe is spring back from setting around after bullet seating.

I don't understand your above numbers. Did you have a Typo? Matt

 

[Tozguy]

It makes sense that a 'peak' could be associated with the yield point of the brass. Would it not be possible to get an idea of where this peak is for a specific brass lot by seating a bullet and then pulling it? The neck OD of the empty unfired neck should indicate a threshold beyond which there is no extra tension to be added by smaller neck sizing.
Could this become a way to determine when its time to anneal or time for a bushing change?

I have tremendous respect for the time and effort some of you put into testing.
I have tremendous respect for anyone who can shoot a 5'' group or under at 1000 yds.
I have even more respect for someone who realizes that this does not make them a scientist.

However it is the science of it that fascinates me. It is very hard to explain why a certain load will shoot one day and not every day. Once I get the bullet/powder and seating depth sorted out for repeatable good performance I go to a barrel tuner. But none of this is happening at more than 200 yds. You 1000 yd guys are amazing.

 

[LHSmith]

However it is the science of it that fascinates me. It is very hard to explain why a certain load will shoot one day and not every day.

This is why I try not to fill my head with theories. I test, take notes, and prepare for the next match in conditions that seem to prevail at that venue. When I go to the line, I can better keep focus on the task at hand.....my mind is not left wondering about the "why's" of what makes a load work. Being simple -minded, I am satisfied just knowing "how" to keep a load working.
At a typical match(short-range),in the loading area you hear enough "theory" to make your head spin. I learned long ago to keep my muffs on and ignore the chatter....what work's for one does not necessarily work for others.

 

[Joe Salt]

And the Guys with the most record please Stand up! These guys are trying to help you none believers. I believe It works.

Joe Salt

 

[dkhunt14]

And the Guys with the most record please Stand up! These guys are trying to help you none believers. I believe It works.

Joe Salt

That would be a tough one JOE. Matt

 

[Joe Salt]

Matt Like I tell people this is not Hollywood other than the guys and Woman that shoot, your not Tom Cruise! What tic's me off is the guys that don't believe you when you tell them about something you have tried that works. They must think we lie like Hillary.

Joe Salt

 

[dkhunt14]

Matt Like I tell people this is not Hollywood other than the guys and Woman that shoot, your not Tom Cruise! What tic's me off is the guys that don't believe you when you tell them about something you have tried that works. They must think we lie like Hillary.

Joe Salt

No he's called TOM Mousel or Mighty Mousel Matt

 

[SHootSTraight22]

Have any of you guys ever used the shape of the carbon ring around the neck to aid in tuning neck tension?? I've seen by looking at the carbon ring shape when I need to adjust neck tension.. The results seem to be seen on paper as well... It seems to me one needs a sine/cosine shape and ring on the lower half of the neck for proper release and expansion of the neck... What about yall???

 

[dmoran]

...... It seems to me one needs a sine/cosine shape and ring on the lower half of the neck for proper release and expansion of the neck.....

Interesting....
Could you post pictures showing the shape/ring to what you feel is good (and bad would be great as well).
Thanks
Donovan

 

[SHootSTraight22]

Interesting....
Could you post pictures showing the shape/ring to what you feel is good (and bad would be great as well).
Thanks
Donovan

I don't know how to post pics, had to have someone do it for me on here last time... Just imagine a perfect ring around the case neck but with a sine shape on one side and a cosine shape mirroring it directly opposite.. This is when neck tension is right compared to the carbon ring being smudged around the neck or even down into the shoulder area... When it's down in the shoulder or smudged badly it seems to be to little tension from what I've seen and someone needs to add about .002 of tension.... Possibly when the ring seals in a perfect circle just above the shoulder then tension may need to be less so the case seals higher up the neck...

 

[Dusty Stevens]

Those waves appear with perfect neck clearance not relative to tension. Youll have 2 dips on a 2lug action and 3 on a 3lug. Tony boyer writes about this in his book. I have tested it and it does go away with more clearance starting around .003 on a loaded round. If youre seeing it on anything but an extreme low clearance ppc you should turn your brass a tad more

 

[Joe Salt]

If you want a crimp Lee makes the die's to do that! I wonder why they would do such a Dumb Thing?

Joe Salt