Competition Tuning with neck tension

[Tim Singleton]

Would some folks with experience in tuning with neck tension talk about what they do?

More specifically what the target tells you that you then make an adjustment lighter or tighter

Im not to interested in chronograph information.
Just what you see on the target

 

[BartsBullets]

Would some folks with experience in tuning with neck tension talk about what they do?

More specifically what the target tells you that you then make an adjustment lighter or tighter

Im not to interested in chronograph information.
Just what you see on the target

Tim,
You should come to the house sometime and shoot. We could play with some of this stuff.

When Tony was working with me, I asked him about neck tension and he said it was the last thing he tested as far as tuning.

It’s a lot bigger deal at long range then it is for us short range types.

Bart

 

[Alex Wheeler]

Neck tension does not change your tune. So you can do all of your load work then just shoot that load with different neck bushings. Bart is right, is a really big deal at long range. So much so that some of us test it first. You can just run a standard ladder test at long range with each bushing you want to test and it will be obvious, then you start tuning. I have had barrels I almost pulled off because they shot so bad, until I tested NT and they shaped right up. The wrong bushing at LR is a deal breaker. I have done a little testing in my ppc and it still shows up but its not as drastic.

 

[BoydAllen]

Back in the day, I was shooting a good load (based on group size) for a 6mm PPC. I was shooting 133 with frederal primers.) My standard load was with .003 neck tension. The chamber had a .262 neck so case necks were around .0086. (More recently I am using more clearance and slightly thinner necks.) Since I had the bushings needed to test both .001 and .002 neck tension, and conditions were good. I shot groups with both. The results clearly showed that with .001 the group was a lot bigger, a little smaller with .002 and the best with .003. This is just another example of the advantages of loading at the range. It allowed me to adjust my initial load to peak accuracy before starting the test. One more thing worth mentioning is that those results were only for that particular powder. Another powder that is used for that caliber, LT32 shoots better with .001 to .0015 neck tension.

 

[DaveTooley]

I've found if I err on the tighter side I seem to get more consistent results in both SR and LR. YMMV
Time to fireform some brass for next week.

 

[marchx]

Very important question by @Tim Singleton. I test 0.001-0.003 NT at 200m and after few sessions I pick up the NT that gives me consequtively smallest groups.

 

[AICS308]

Could this test be done with one size bushing then adjusting final neck tension with different mandrels? Would the results still be reliable?

 

[Schippergreg]

Back in the day, I was shooting a good load (based on group size) for a 6mm PPC. I was shooting 133 with frederal primers.) My standard load was with .003 neck tension. The chamber had a .262 neck so case necks were around .0086. (More recently I am using more clearance and slightly thinner necks.) Since I had the bushings needed to test both .001 and .002 neck tension, and conditions were good. I shot groups with both. The results clearly showed that with .001 the group was a lot bigger, a little smaller with .002 and the best with .003. This is just another example of the advantages of loading at the range. It allowed me to adjust my initial load to peak accuracy before starting the test. One more thing worth mentioning is that those results were only for that particular powder. Another powder that is used for that caliber, LT32 shoots better with .001 to .0015 neck tension.

Be sure to test with lt32 also. I’ve had better success with a bushing .003 under loaded neck diameter.

 

[L.Sherm]

Could this test be done with one size bushing then adjusting final neck tension with different mandrels? Would the results still be reliable?

I prefer bushings only but there's only one way to find out and that is test it.

 

[Tim Singleton]

Tim,
You should come to the house sometime and shoot. We could play with some of this stuff.

When Tony was working with me, I asked him about neck tension and he said it was the last thing he tested as far as tuning.

It’s a lot bigger deal at long range then it is for us short range types.

Bart

Bart
id love to take you up on that

I had been working with a new barrel. I usually use a 260 bushing loaded round is 266
it kept popping one out like a hot load does changed to a 262 bushing and it seemed to help

 

[Jerry Wick]

Bart
id love to take you up on that

I had been working with a new barrel. I usually use a 260 bushing loaded round is 266
it kept popping one out like a hot load does changed to a 262 bushing and it seemed to help

Tim, boattail or flatbase bullets?

I'll guess boattail as those seem to be the most popular lately.

 

[Northridge]

I find so often that short range is almost the hundred percent opposite for good results vs long range approach… I’m of the approach for long range if bushing or Hold is correct everything else follows so I verify that early on if “color affinity “ is lacking and or general shape is not favorable ….

Shawn Williams

 

[Tim Singleton]

Tim, boattail or flatbase bullets?

I'll guess boattail as those seem to be the most popular lately.

Yes boat tail

 

[jackieschmidt]

I generally shoot a rather light neck tension in my 30BR, my 6PPC, and my 66BRA. With my 30BR, it is just enough to hold the bullet.

So I do not tune with neck tension. I have three other things to tune with, powder charge, seating depth, and the tuner.

 

[Alex Wheeler]

One thing I will ad is that I normally test up to .005" but have had customers send test data up to .010" of NT. The groups keep changing. I know that at some point the neck will yield but the paper says it still matters. If I want to be lazy Id test .002 vs .005. Those are the two main areas. But theres still some that have preferred less than .001 and in the middle around .003.

 

[BartsBullets]

I find so often that short range is almost the hundred percent opposite for good results vs long range approach… I’m of the approach for long range if bushing or Hold is correct everything else follows so I verify that early on if “color affinity “ is lacking and or general shape is not favorable ….

Shawn Williams

You nailed it. What is critical in long range often isn’t in short range, and vise versa. Which has caused some heated exchanges on here at times.

Bart

 

[Tim Singleton]

I’m a little hard headed at times which isn’t good. I’ve been in the Jackie camp and never messed with it used my tight bushing and tuned with everything else.

Testing at 300 yards showed me I had a problem. No matter what I did I had a shot or two popping out of the group like it was too hot. Finally thought well lets try a different bushing a 262 was the biggest I had and right away the jumper went away

 

[Tim Singleton]

When you say popping out of the group, do they look like these ? I’m thinking I have a touch too much hold on this brass. It’s sure acting like what you’re describing.

Yep
pretty spot on
at 300 yards 3 in a tight wad two out the bottom.

 

[Tim Singleton]

Bushing change

 

[RustyInBend]

Would some folks with experience in tuning with neck tension talk about what they do?

More specifically what the target tells you that you then make an adjustment lighter or tighter

Im not to interested in chronograph information.
Just what you see on the target

It's like pretty much everything else ... start with a low starting point, and gradually increase until you see the perfect intersection of SD, ES, consistent Velocity, and tight groups near and far. There's no magical system ... you just have to do the work. That said, my AMP Press makes it MUCH easier to quantify neck tension and definitely shortens pretty much all fact-finding missions I've gone on that have anything to do with neck tension. If you don't have an accurate way to measure seating force, at the end of the day, everything is a "guess".