How do you incorporate neck tension into your load development?

[tom]

Below is a 1000yd Neck-tension test that shows significant variation in dispersion between 0.001" increments in bushings used:


View attachment 1443656

I found notes to go with this !
6-6-2015 40°
Ff+3 non annealed (ever) lapua cases
6 dasher (so 2016) lol
269 neck
2665 loaded
Lot 6503 VT
32.375 h 4895
Seated 2.874 (+7)

262 Wilson = 4.0 holds and is what tune was started on. +- 41 lbs, held 2.5 vertical but got wide for whatever reason.

Vs. 264 TN redding= 3.3 holds. +- 37lbs and went vertical bad , about 5.5.


Vs. 263 TN redding = 4.7 holds. +-51lbs, and held 1.6 vertical for a 1.8 group, and became the "new pet load" until further testing. I wound up staying on the 263tn after those follow ups.

To add to the conversation, I do believe I learn more comparing powder ladders to one another loaded each at differing tensions. But this is also comparable doing groups x vs y vs z as well, as I've not seen any difference in final powder charge after going full circle on a barrel yet.

Tom

 

[JFrank]

@tom
Damn’ those are good notes.

 

[tom]

@tom
Damn’ those are good notes.

I remembered most of it in my head from 2015 lol.

Tom

 

[Longtrain]

Usually .002 of tension, some of my buddies use mandrels to get to .001. It works for me.

 

[Dimner]

No rule really

So ...having followed the statistics thread where you explained powder selection testing, would you try neck tension after your powder selection test? Something like

1)powder choice test
2)neck tension
?)bullet seating
?)charge

Until you get to bullet seating would you test 0.010 off the lands or touching?

 

[Dimner]

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.

You will never learn anything with three shot groups I kid!

 

[Dimner]

Reading this post has me thinking.

I have noticed that when I seat my bullets some are as smooth as silk and other take a higher pressure to start the seating motion.

I have wondered many times shooting at 1K, why one shot would be .5-1 MOA higher that the group. I'm thinking maybe the higher tension was causing the pressure to build higher in the case before the bullet started moving. Thus causing a higher FPS at the target (some times as high as 40 FPS faster) to cause the higher POI.

The next time I seat my bullets I will take the ones that took a little more pressure to start it, mark them and see if my thinking is correct.

This was happening to me, the seating pressure, not the long range results as I don't have a place to shoot that far. I started off marking the cases like you suggest, but found that around half worked like I expected and the other half were problem cases.

But it all worked out when I changed from hand annealing to using an automatic annealer. Also annealing after every use. My neck tension became very consistent. I should also mention I switched to forster benchrest dies, but I'll bet a whole 2 dollars it was the consistency of my annealing that made it better.

 

[spudgun]

This was happening to me, the seating pressure, not the long range results as I don't have a place to shoot that far. I started off marking the cases like you suggest, but found that around half worked like I expected and the other half were problem cases.

But it all worked out when I changed from hand annealing to using an automatic annealer. Also annealing after every use. My neck tension became very consistent. I should also mention I switched to forster benchrest dies, but I'll bet a whole 2 dollars it was the consistency of my annealing that made it better.

I do anneal, but not fter every shot. I maybe do about 2-3 times a year. I have about 200 cases of Starline brass and usually wait until I have used most of them then anneal.

 

[Northridge]

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.

Agreed Alex, there are lots of barrels in the corners of reloading rooms that ended up there do to a bushing combo that simply wasn’t proofed.. if the bushing is “correct” for a given situation the platform will not resist clean windows within a given ladder rather “wrong” bushing will develop finicky unpredictable ladders… if you have to “force” a gun to shoot or tune likely the bushing is not correct for the combo of barrel , bullet or powder

Shawn Williams

 

[Skedaddle Shooter]

I found notes to go with this !
6-6-2015 40°
Ff+3 non annealed (ever) lapua cases
6 dasher (so 2016) lol
269 neck
2665 loaded
Lot 6503 VT
32.375 h 4895
Seated 2.874 (+7)

262 Wilson = 4.0 holds and is what tune was started on. +- 41 lbs, held 2.5 vertical but got wide for whatever reason.

Vs. 264 TN redding= 3.3 holds. +- 37lbs and went vertical bad , about 5.5.


Vs. 263 TN redding = 4.7 holds. +-51lbs, and held 1.6 vertical for a 1.8 group, and became the "new pet load" until further testing. I wound up staying on the 263tn after those follow ups.

To add to the conversation, I do believe I learn more comparing powder ladders to one another loaded each at differing tensions. But this is also comparable doing groups x vs y vs z as well, as I've not seen any difference in final powder charge after going full circle on a barrel yet.

Tom

In your notes what does the “=4.0 holds” mean?

 

[tom]

In your notes what does the “=4.0 holds” mean?

That would be .0040" difference between sized and loaded dimensions.

Tom

 

[Alex Wheeler]

So ...having followed the statistics thread where you explained powder selection testing, would you try neck tension after your powder selection test? Something like

1)powder choice test
2)neck tension
?)bullet seating
?)charge

Until you get to bullet seating would you test 0.010 off the lands or touching?

It depends on how the tuning is going. If things are looking good an tunable I will test NT almost last. If I am struggling with the tune I will jump to bushing test right away.

 

[Alfred]

Agree. Lacking any proper tools, consider a well-calibrated Kinetic bullet puller

I like it, a well calibrated hammer............

 

[Bill Norris]

You will never learn anything with three shot groups I kid!

Did u by chance miss the last sentence ? LOL.

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.

 

[Dimner]

Did u by chance miss the last sentence ? LOL.

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.

Oh, I did miss it. but I was just being a smartarse anyway. 5 shot or 3 shot to each his own.I was just mimicing those voices that praise the 5 or ten shot group. I'm sure you have forgotten more about this sport than I have learned as of yet.

 

[Bill Norris]

Oh, I did miss it. but I was just being a smartarse anyway. 5 shot or 3 shot to each his own.I was just mimicing those voices that praise the 5 or ten shot group. I'm sure you have forgotten more about this sport than I have learned as of yet.

And I was only kidding you too Bro. No worries at all.

 

[spudgun]

Reading this post has me thinking.

I have noticed that when I seat my bullets some are as smooth as silk and other take a higher pressure to start the seating motion.

I have wondered many times shooting at 1K, why one shot would be .5-1 MOA higher that the group. I'm thinking maybe the higher tension was causing the pressure to build higher in the case before the bullet started moving. Thus causing a higher FPS at the target (some times as high as 40 FPS faster) to cause the higher POI.

The next time I seat my bullets I will take the ones that took a little more pressure to start it, mark them and see if my thinking is correct.

Well, I reloaded 50, 6.5 CM for my shooting this morning. I did have 15 rounds that took more force to seat the bullets than the other 35.

This morning I was shooting 1000 Yds and Shot 5 easy bullets and 5 bullets that took more pressure to set. Out of the 10 rounds I had a SD of 6.9. Really did not see any difference in FPS. Went ahead and shot 5 more of each and they performed equally.

Then went to the 1200 yd range shot the remaining 5 hard to seat and same thing.

I was hoping that I would get different readings so I could make sense of why I was getting in some times 40FPS fast/slower reading on the target.

Logic tells me that if it takes more pressure in the case to push the projectile out of the case it should increase FPS. Right???

Maybe in my situation neck tension does't matter that much.

 

[rhovee]

I did a risky move. Load work up on fired brass not annealed. The. Annealed. (Big case .0055 neck clearance). My original bushing was now sizing the necks more than previously. So did a quick NT test. Only had (2) different mandrels since the necks were already sized to much. 300 Norma that Alex chambered for me. 100 yards. 10.5 pound rifle scoped. Bipod rear bag.

 

[Chilly807]

This is a heck of a rabbit hole.
My 2 regularly-shot rifles are in 6.5 CM and 223 Rem.
The 6.5 with annealed-on-every-firing Lapua brass is boringly consistent, SD under 10 fps is easy to get. Very low neck tension judging by the effort required at the press handle.
The 223 needs more neck tension, and even then it's a struggle.
My experience has been that as the brass ages and hardens, you need less neck tension. The harder brass grips the bullet more tightly than when it was new. This becomes problematic, since you can't be sure how much tension you'll have til you seat the bullet.

Even then, let's say you can quantify how much pressure it took to seat 25 rounds. If you have any significant difference between them, what do you do? Sort them into 3 groups? "Probably slower", "average", and "probably faster"?

At short range, it's not as critical. As you stretch things out, if your neck tension is inconsistent enough to affect combustion you're going to get vertical stringing. I know this from experience.

Neck tension can be measured 2 ways. The first is as a purely static physical dimension, 2 thou for example. This isn't a great way to operate, because it doesn't take into account brass condition, such as hardness, inside neck surface finish, etc.
The second way is much more relevant. It is a measure of how much pressure is required inside the case before the bullet starts to move. Realistically, you can only measure that by knowing how much force it took to seat the bullet, and that's assuming you don't have any cold welding between the bullet and the brass.

This all assumes your primer strength and powder charges are identical, etc.

I believe the reason a lightly jammed bullet in a low neck tension load leads to very consistent velocities is because pressure has a chance to build before the bullet can move, and it's the same every time.

That approach isn't everyone's cup of tea, including me. I want to be sure I can eject a loaded round without leaving a bullet stuck in the lands.

Like I said earlier, a rabbit hole. If you have a cartridge that's tolerant of annealing, there's a good reason annealing is so popular. You can "reset" your neck condition to zero at every firing.
If you have a cartridge that needs more neck tension to operate well, then you might have to get creative to achieve that goal.