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How do you incorporate neck tension into your load development?

HTSmith

Silver $$ Contributor
My process up until now is to find a seating depth by starting at hard jam and working my way back .003" at a time. Then I'll work on the powder. With the 6BR and Dasher I know about what powder range to use. I've not really used neck tension as "tunable" variable. I use a bushing .002" under the loaded round neck diameter and run with it. It has worked well enough and I figured when I'm seating pretty deep into the lands it shouldn't make much of a difference. Watching the groups folks were getting at a recent 600 yard IBS match is making me think about upping my game.

So long story to ask a short question. How do you incorporate neck tension into your load development process?
 
This isn't a difficult proposition and you already know the answer.... test.

Your starting point is just fine and that 0.002" NT is a rough figure to aim at with just about any typical 6mm centerfire.

Almost every recipe has a share of elastic and plastic stress/strain in the neck. Those amounts and the effect on the seating force or grip on the bullet are non-linear but that 0.002" is a good starting point for 6mm.

Considering we are not discussing a full or semi-auto, I would say you shouldn't have a struggle to adjust your recipe up and down a little and run yourself an exploratory test.

Just keep all the other recipe details under control to get a well organized look at the effects without chasing your tail. Details like cleaning, annealing, chamfer, brushing or lubing, etc., all have their say so make sure you are only changing your NT diameter and not three things at once.

Some guns/ammo live in a wide NT window where they perform very well and forgive NT changes, but others will hit a place where the performance can tip. Sometimes, a change in NT demands a change in depth and/or charge to come back into tune. Sometimes it has no significant effect on the target.

The caliber (diameter), the composition and thickness of the brass, the cold work state, friction coefficient, base style of the bullet and jacket composition, etc., all have a potential effect but they may or may not affect your groups either way. Only your own testing in your exact context can answer the question.
 
marchboom said:
I don't run my bullets into the lands. I start at .010" from the lands and use a mandrel that will give me .002" neck tension. But I guess if you jam the bullets into the lands neck tension doesn't matter that much.
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I am .006 into the lands and use a .264 bushing in my rifle.
Some powder and bullet combos need it.
 
HTSmith said:
I know you are right, but I was hoping for a shortcut:) Thanks for the detailed answer.
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In some places in life, the folks on the podiums are prodigies or they rocketed there with the help of strong mentors. Most of the time, the folks on those podiums have put in the work and struggled to get there.

We have a juniors team in CA that is very successful called the Grizzlies. We hand them the recipes and advice and they get to focus on the shooting. Some will take it upon themselves to go explore the boundaries on their own and some never will. In my view, the ones that take that upon themselves will be stronger performers in the long run. They will not only know what to do, but they will know the why and how much before things fall apart.

The 6 BR and 6 Dasher are a shortcut, as are working with really good brass, powders, bullets, etc.

The 0.002" NT starting point is yet another short cut if you think about it.

Once we are past "the shortcuts", we are doing you no favors if we tell you everything else is easy. Folks owe it to themselves to do both, that is, take advantage of the advice and shortcuts, but also to run their own testing when they have the opportunity.
 
I also do seating, then powder, then if I’m really curious primer.

I have tested neck tension on several occasions and .002-.003 has always worked the best or more than good enough. I mostly care about 0-600 yards, and I have heard Alex say that more tension helps at 1,000, but I have not yet had the need to try it.

I do believe that tension is an independent variable that can be tested at any point during the process.
 
Doing load test is another reason to go shoot, it can also be rewarding!
and yes some one’s shortcut can be helpful if used as a starting point. I’ve heard people at matches that didn’t do shoot good say “ well Joe Blow on the internet said he won with this load” but that was in his rifle.
load testing can be rewarding because
1 you did it yourself
2. it’s custom fit to your gun with you pulling the trigger
3 you not only learn what YOUR gun likes but also what it don’t like
just my $.02
 
Seating first has never worked for me unless I already knew the powder from previous experience. Neck tension does not seem to change the rest of the tune. So if things are going well you can take your final load and just try different bushings. However if you are fighting the tune and you feel like you shoudnt be then I would go with the best load you had and jump right to the bushing test. Neck tension is by far the most overlooked part of the tune and yet its as important as seating or powder.
 
Neck tension testing will be the last item for me. If I test it would be .001 or .002 on either side of whatever I was loading with when I began load work-up. According to the Pros, neck tension is in the Combustion Category. Sam Millard of Panhandle Precision says he will only test neck tension if he cannot get low E S numbers.
 
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If theres anything I could change about the way people work up a load its the lack of neck tension testing. I dont know why its this way but you cant tune a rifle on the wrong neck tension. Its citical. I had my eyes opened by Shawn Williams and Tom Mousels testing. I used to be a .002 nt guy too.
 
Alex Wheeler said:
If theres anything I could change about the way people work up a load its the lack of neck tension testing. I dont know why its this way but you cant tune a rifle on the wrong neck tension. Its citical. I had my eyes opened by Shawn Williams and Tom Mousels testing. I used to be a .002 nt guy too.
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Did the test show the loads wanted more neck tension or less as a general rule ?
 
Reason I asked that question is this is a test I did with my 30BR back when I was almost done with load work-up for it and saw the 5-shot groups open up on both sides of the .324 in which I was using to develop the load.
 

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Brx6 said:
Doing load test is another reason to go shoot, it can also be rewarding!
and yes some one’s shortcut can be helpful if used as a starting point. I’ve heard people at matches that didn’t do shoot good say “ well Joe Blow on the internet said he won with this load” but that was in his rifle.
load testing can be rewarding because
1 you did it yourself
2. it’s custom fit to your gun with you pulling the trigger
3 you not only learn what YOUR gun likes but also what it don’t like
just my $.02
Click to expand...
I hear ya, but the dang bullets cost $.60 each and an itty bitty primer costs a dime. Never mind the $700 barrel that you can use the better(best) part of its life testing loads. On top of that it takes a year to get a barrel and good 'smiths ain't sitting around waiting for work. Whew! I feel better now that I got that out ;)
 
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