Doesn't matter what I do... Neck Tension Variance

[Chiquita]

I anneal with AMP every firing, I use good brass (Peterson, Lapua, Alpha), my anvil crush is about 6 to 9 thou, use good bullets (Berger, Barnes, Nosler), good dies (SAC), T7 press, I have tried with and without mandrel.

Doesn't matter what I do, I can't get a consistent neck tension. I have even trimmed all using Giraud trimmer and have about 3 seconds of dwell time in the press.

Is it just the nature of the brass, doesnt matter what I do, I will have certain percentage of cases will never be consistent?

What else am I missing? How do you keep you neck tension consistent?

TIA for your replies.

 

[Superjet]

Do you tumble after you anneal? I flame anneal and have noticed I get some “sticky seating” on cases if I do the tumble after annealing. I am dry tumbling with corncob.

 

[Forum Boss]

1. Use a good single-stage press for case sizing.

2. Seat bullets with a high-quality arbor press with dial gauge.

3. Consider getting a custom, non-bushing sizing die.

4. Do NOT over bevel the necks. A couple spins with a simple 45-degree chamferer (with a quick back spin) may be enough, and you may not have to do that with every loading.

5. Check the DIAMETER of your bullets. We've seen variance of up to .0008" among bullets of same caliber from different makers/different lots.

 

[bugman]

I anneal with AMP every firing, I use good brass (Peterson, Lapua, Alpha), my primer crush is about 6 to 9 thou, use good bullets (Berger, Barnes, Nosler), good dies (SAC), T7 press, I have tried with and without mandrel.

Doesn't matter what I do, I can't get a consistent neck tension. I have even trimmed all using Giraud trimmer and have about 3 seconds of dwell time in the press.

Is it just the nature of the brass, doesnt matter what I do, I will have certain percentage of cases will never be consistent?

What else am I missing? How do you keep you neck tension consistent?

TIA for your replies.

How.....exactly....did you arrive at that conclusion? What criterion? Measuring sized and expanded outside dimension versus seated OD is not reliable unless you have perfectly turned brass and perfectly consistent bullet OD.

If you are basing our complaint on seating force.....Try brushing the inside of the neck with a blue (iosso brand) stiff bore brush AFTER annealing and/ or before seating.

 

[Steve Donlon]

Are you cleaning out the inside of the neck after annealing, then lube inside the neck before seating the bullet?

 

[Sniper338]

Oh what a rabbit hole. I went down this road years ago. Do what forum boss said. Then become a mad scientist and change one thing at a time. You. An narrow down your process some... but you will never be 100% across the board. I couldnt do it. Get a good chrono and test different seating forces, batches of close to the same.

Its a rabbit hole.

Gotta measure everything... group everything...

Then when you find the bottom of the rabbit hole you figure out that different neck tensions still somehow shoot the same velocity sometimes.

I got to be a better reloader with this rabbit hole. Learned a bit..

I still cant get everything perfect though. I don't think anyone can. Its just another factor that makes shooting competitive.

 

[Fire Dog]

How.....exactly....did you arrive at that conclusion? What criterion? Measuring sized and expanded outside dimension versus seated OD is not reliable unless you have perfectly turned brass and perfectly consistent bullet OD.

If you are basing our complaint on seating force.....Try brushing the inside of the neck with a blue (iosso brand) stiff bore brush AFTER annealing and/ or before seating.

This^^^^^^^^^^^
I wet pin clean and AMP anneal @ time and power brush {Iosso blue} the inside of the neck, light touch of chamfering inside and out and let Neolube #2 or a home brew of ultra fine graphite & Isopropyl alcohol mix be your friend before using a mandrel and you should find that seating force will be much reduced.
Turning the case necks, even if you have a “No Turn” chamber, will also help as a very light skim will ensure that the neck thickness is consistent, also adding to consistent seating force.

 

[Webster]

I anneal with AMP every firing, I use good brass (Peterson, Lapua, Alpha), my primer crush is about 6 to 9 thou, use good bullets (Berger, Barnes, Nosler), good dies (SAC), T7 press, I have tried with and without mandrel.

Doesn't matter what I do, I can't get a consistent neck tension. I have even trimmed all using Giraud trimmer and have about 3 seconds of dwell time in the press.

Is it just the nature of the brass, doesnt matter what I do, I will have certain percentage of cases will never be consistent?

What else am I missing? How do you keep you neck tension consistent?

TIA for your replies.

Neck diameter is not gripping strength. There is an assumption that if if the diameters are the same the bullets are gripped the same. What you need is called hoop strength which we cannot measure. It assumes that if each case is processed the same every neck will have the same residual stress, the same hardness, tensile strength and yield strength. Also tiny variation in bullet diameters. Erik Cortina has a video where he annealed, did case prep and measured bullet seating pressure. The pressure varied a lot. Maybe it's not important. Let the targets tell you if it affects accuracy.

 

[Jdne5b]

How are you determining neck tension, and what variance are you seeing?

 

[CoupleKimbers]

I anneal with AMP every firing, I use good brass (Peterson, Lapua, Alpha), my primer crush is about 6 to 9 thou, use good bullets (Berger, Barnes, Nosler), good dies (SAC), T7 press, I have tried with and without mandrel.

Doesn't matter what I do, I can't get a consistent neck tension. I have even trimmed all using Giraud trimmer and have about 3 seconds of dwell time in the press.

Is it just the nature of the brass, doesnt matter what I do, I will have certain percentage of cases will never be consistent?

What else am I missing? How do you keep you neck tension consistent?

TIA for your replies.

Are you turning your brass? If you are not turning your brass to a specific thickness, you are left with factory variations that could be causing issues. Thicker brass requires more annealing, and different thicknesses will spring back differently, causing variations in neck tension. I measure neck tension by the diameter of the unloaded neck after it has been run through a bushing. If you are not consistent with your brass prep steps and you don't turn necks, things can go south pretty quickly.

 

[Chiquita]

1. Use a good single-stage press for case sizing.

2. Seat bullets with a high-quality arbor press with dial gauge.

3. Consider getting a custom, non-bushing sizing die.

4. Do NOT over bevel the necks. A couple spins with a simple 45-degree chamferer (with a quick back spin) may be enough, and you may not have to do that with every loading.

5. Check the DIAMETER of your bullets. We've seen variance of up to .0008" among bullets of same caliber from different makers/different lots.

I have the T7 press with Creedmoor Sports head.

I bevel by 2 to 3 light pressure turns.

I use Wilson arbor press with 21st century press.

I will have to check the diameter of the bullets.

 

[Chiquita]

@bugman I came to the conclusion that some are harder to seat. I will try the blue brush next time.

 

[JFrank]

Seating force and neck tension ( bullet hold ) are two different things.

 

[Chiquita]

@CoupleKimbers
I don't turn the brass. I don't trim every time either. Other than these two everything else is consistent. I will try the brush and the mica on the necks before seating and see if it makes a difference on seating consistency.

 

[Chiquita]

Seating force and neck tension ( bullet hold ) are two different things.

Doesn't the extra seating force to seat mean more grip on the bullet hence more pressure to release the bullet after firing?

 

[gmr4]

I anneal with AMP every firing, I use good brass (Peterson, Lapua, Alpha), my primer crush is about 6 to 9 thou, use good bullets (Berger, Barnes, Nosler), good dies (SAC), T7 press, I have tried with and without mandrel.

Doesn't matter what I do, I can't get a consistent neck tension. I have even trimmed all using Giraud trimmer and have about 3 seconds of dwell time in the press.

Is it just the nature of the brass, doesnt matter what I do, I will have certain percentage of cases will never be consistent?

What else am I missing? How do you keep you neck tension consistent?

TIA for your replies.

6 to 9 though on primer crush.. thats something Id be thinking about…

Run a mandrel that is 2 thou under bullet diameter.. size neck down with bushing then back up with the mandrel. MAKE SURE the necks are not too clean… I use Neo Lube 2 inside the neck.

 

[Chiquita]

How are you determining neck tension, and what variance are you seeing?

Brass thickness x 2, plus the diameter of the birdie then subtract .002. That gives me the size of the neck bushing.

 

[Chiquita]

6 to 9 though on primer crush.. thats something Id be thinking about…

Run a mandrel that is 2 thou under bullet diameter.. size neck down with bushing then back up with the mandrel. MAKE SURE the necks are not too clean… I use Neo Lube 2 inside the neck.

I just dump the neck into the neo lube/mica or there ie better method that is less messy?

what about the crush?

I take the depth of teh primer pocket minus the height of the primer. The result is deducted from the primer seating depth.

 

[gmr4]

I just dump the neck into the neo lube/mica or there ie better method that is less messy?

I poor a little NEO LUBE into a bottle cap after shaking it up really good then dip a q tip.. swab the inside of the neck.. I doesnt take long to do 100

 

[ronemus]

Doesn't the extra seating force to seat mean more grip on the bullet hence more pressure to release the bullet after firing?

Under most conditions reloaders are using the bullet as a sizer - most of the seating force is used to expand the neck. The neck will contract 0.001-0.0015" after expanding, and that's all the contributes to bullet retention. I take the approach of using an expander (Hornady elliptical) of full bullet diameter; that maximizes bullet pull while minimizing the work done by the bullet during seating and deformation of the bullet (no ring around the nose). I use custom Hornady elliptical expanders because their profile is a good as a mandrel and eliminates a step in my process.

I wet tumble without pins, using 1 mm SS jeweler's polishing balls instead. They're not as aggressive as pins, but they're too small to lodge and the brass gets clean inside and out. I moly coat my bullets, so there is no need for lube and bullets don't cold weld.

I use an Induction Annie to anneal (actually stress relieve) every firing, so neck hardness remains consistent. I also trim every time using a Gracey with a Giraud cutter so chamfers are fresh and neck lengths are uniform.

I'm not set up to measure either seating force or bullet pull, but they feel consistent when I make or break down ammo.