+- .004 Neck tension too much?

[TimberHunter]

I am a new reloader and self taught through many, many hours of reading so bare with me...


I’ve had issues with case stretch when using a FL side to bump the shoulder back .001-.002. I was getting case stretch of approx .010” every time I ran it through the FL die (I tried a Hornady die and RCBS)

Finally decided to sand/polish the expander ball. I reduced the expander ball thickness by approx .0015. This helped reduced by case stretch from .010 to .005 (still trim some cases every time after a resize tho).

By reducing the expander, I increased the neck tension. Measuring the outside of 10 sized case necks I get .298-.299. Measuring 5 cases that were sized the same way and had a 130 Nosler BT bullet put in it, I get .302-.303. So I’m looking at approx .004-.005 neck tension.

I shot the reloads yesterday at 300 yards and a four shot spread approx 1” vertically and horizontally by approx 2.5”. So group is under MOA which is good for me for a light weight hunting rifle shooting prone in the dirt.

My primers don’t have cratering and the bolt isn’t hard to open so I don’t think I’m having any high pressure issues. Is there any negative effects to having too much neck tension?




Info: 270 win, 22” barrel, 58.5 grains of H4831 SC, 130grain nosler BT, Hornady brass. Chronograph said approx 3020 FPS but I think I’m closer to 3000fps per the inches dropped at 300 yards


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[mtswampfox]

using a carbide expander ball helps. Have been playing with lanolin/alcohol lube. Placing fifty cases in a loading block and spraying directly into the necks. This lube works really well for me. Have also used redding s type dies for most bolt guns,,no stretch here and you can set your tension exactly where you want.Good luck

 

[WestexSBK]

No. .004” is not too much tension.

 

[tdot]

Stretching the cases that much seems excessive. Maybe reconsider what lube you are using, or how you are applying it.

Possibly switch to a bushing die with no expander ball or a separate expander mandrel.

Only testing your loaded ammo will truly reveal if .004 is too much. But generally it is unlikely that it is.

 

[TimberHunter]

Stretching the cases that much seems excessive. Maybe reconsider what lube you are using, or how you are applying it.

Possibly switch to a bushing die with no expander ball or a separate expander mandrel.

Only testing your loaded ammo will truly reveal if .004 is too much. But generally it is unlikely that it is.

I’ve used Hornady paste as well as Hornady one shot, whether I use a lot or little, they stretch not mater what.

I believe the issue is that my chamber may be on the larger size and the FL dies are on the small side. That plus the factory expander ball results in .004-.007 stretch. I’ve have a carbide expander ball for my RCBS FL die coming today and hopefully that’s helps minimize stretch.

Because how much my cases are stretching, I plan on throwing them away after 4 or so firings.


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[WestexSBK]

Have you considered using an expander mandrel to set neck tension?

Joe S

 

[tdot]

Just a thought, if your chamber is on the large side. Maybe don't bump the shoulder back .002. It can take multiple firings for the case to fully form to the chamber. You might be working the brass alot more then needed.

After the first firing on new brass, I only resize so that the neck is resized and the shoulder does not get pushed back at all, though the body will be slightly re sized. Then I ensure that it chambers easily. Repeat for 2 to 3 firings. Once case growth stops, then I bump .002. And continue to do so, from that point forward.

A couple more thoughts.

If you are really working the brass hard, by stretching it into a large chamber. Then you might be work hardening the brass, more then usual. Which may be why the expander ball is stretching the neck. Maybe consider annealing. You can do it with a propane torch with a few to see if there is any improvements.

Where is the additional length coming from? As the expander ball comes through the neck. Is it increasing the length of the shoulder, or the position of the shoulder? If it still chambers easily, even with this increase in the shoulder, then I'd guess that the brass is being oversized in the first place.

 

[TimberHunter]

Have you considered using an expander mandrel to set neck tension?

Joe S

I have... my understanding is that I would FL size and then used a mandate due to expand the neck. From my readings, depending how small the neck gets sized down, the mandrel may introduce some run out


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[WestexSBK]

I’ve read the same. It’s a tried and true method to produce consistent reloads. Like anything we do someone or something can always induce error. I personally know a large number of people who use an expander, including myself, that have nothing but excellent results. The only place I hear of issues is on these forums. I personally believe runout is a very small issue in the grand scheme of things. Most of which is corrected by seating a bullet, rotating the case 180 degrees, and reseating. If you have a straight chamber the bore will align the bullets when chambered.

Joe S

 

[TimberHunter]

I’ve read the same. It’s a tried and true method to produce consistent reloads. Like anything we do someone or something can always induce error. I personally know a large number of people who use an expander, including myself, that have nothing but excellent results. The only place I hear of issues is on these forums. I personally believe runout is a very small issue in the grand scheme of things. Most of which is corrected by seating a bullet, rotating the case 180 degrees, and reseating. If you have a straight chamber the bore will align the bullets when chambered.

Joe S

Do you mind explaining your sizing process?

1. FL size without expander
2. Then use a Sinclair expanding mandrel to open the neck to .002 or so smaller than bullet diameter?


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[recurveman]

Use a sizing mandrel. I think that is super important part of reloading brass. It will make your neck tension super consistent. I will use the mandrel on brand new brass and it makes it very consistent. I like to run .001 - .002 neck tension depending on the use. .004-.005 isn't the end of the world as long as it is consistent. Expander balls suck. They cause problems and aren't consistent. Always full length size your brass. All the F-class shooters I know full length size their brass and you should too. Remember we need the load to enter the chamber. Brass stretches at times. Trim them as needed. Normally the stretch will slow down the more you shoot the brass. I will trim all of the pieces of brass or none of them.

 

[TimberHunter]

Just a thought, if your chamber is on the large side. Maybe don't bump the shoulder back .002. It can take multiple firings for the case to fully form to the chamber. You might be working the brass alot more then needed.

After the first firing on new brass, I only resize so that the neck is resized and the shoulder does not get pushed back at all, though the body will be slightly re sized. Then I ensure that it chambers easily. Repeat for 2 to 3 firings. Once case growth stops, then I bump .002. And continue to do so, from that point forward.

A couple more thoughts.

If you are really working the brass hard, by stretching it into a large chamber. Then you might be work hardening the brass, more then usual. Which may be why the expander ball is stretching the neck. Maybe consider annealing. You can do it with a propane torch with a few to see if there is any improvements.

Where is the additional length coming from? As the expander ball comes through the neck. Is it increasing the length of the shoulder, or the position of the shoulder? If it still chambers easily, even with this increase in the shoulder, then I'd guess that the brass is being oversized in the first place.

Good point... I had been assmining that once fired brass was a copy of my chamber. But with brass bounce back my shoulder it probably further out then I think.

For example shooting facorey ammo, I get shoulder at .038-.037. How much does the brass bounce back? Possible .001-.002? So my shoulder is actually closer to .040 and I’ve been bumping the should back to .035 which could explain the case lengthiness by .005-.007?


Maybe my chamber isn’t even on the large size of spec, maybe I’m just bumping the shoulder too much.

When fire forming new brass 2-3 times, do I just neck size in between the firings so I don’t bump the shoulder? Side note, I get approx .004” of case stretch when I neck size


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[Rob5589]

Do you mind explaining your sizing process?

1. FL size without expander
2. Then use a Sinclair expanding mandrel to open the neck to .002 or so smaller than bullet diameter?


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Exactly how I would load "match" ammo. Sinclair has different sized mandrels so you can set the neck tension to whatever you want within reason. Been a while but .002 sounds about where I was at.

 

[WestexSBK]

Yes sir,

1. Deprime fired cases.
2. Perform needed brass prep if any. I now own a Giraud trimmer and this is when I will run them through it.
3. Brush out necks with a Nylon brush
4. Gut my sizing die and size cases with a pause at the top of the stroke.
Note: I ONLY use FL sizing dies. Preferably Non-Bushing but sometimes that’s not possible. Select a custom die that sizes minimal assuming this is a custom rifle. Otherwise it doesn’t make a difference.
5. Wipe off lube.
6. Lube inside neck with imperial dry/graphite
7. Expand neck with mandrel
8. Prime
9. Charge
10. Seat bullet with Wilson dies using an arbor press.

I think that’s the just of it. Kind of hard to describe something you just do...

Joe S.

Do you mind explaining your sizing process?

1. FL size without expander
2. Then use a Sinclair expanding mandrel to open the neck to .002 or so smaller than bullet diameter?


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[Mike 338]

4 thousandths is fine. Your testing confirms that.

 

[recurveman]

Yes sir,

1. Deprime fired cases.
2. Perform needed brass prep if any. I now own a Giraud trimmer and this is when I will run them through it.
3. Brush out necks with a Nylon brush
4. Gut my sizing die and size cases with a pause at the top of the stroke.
Note: I ONLY use FL sizing dies. Preferably Non-Bushing but sometimes that’s not possible. Select a custom die that sizes minimal assuming this is a custom rifle. Otherwise it doesn’t make a difference.
5. Wipe off lube.
6. Lube inside neck with imperial dry/graphite
7. Expand neck with mandrel
8. Prime
9. Charge
10. Seat bullet with Wilson dies using an arbor press.

I think that’s the just of it. Kind of hard to describe something you just do...

Joe S.

I do this mostly but I wouldn't put lube inside of my neck at step 6. I only lube the outside of my brass when sizing. At some point in the process you could also use a tumbler or supersonic device to clean the brass if you want. Shiny is always cool!!!!!!!!

The arbor press will totally change how you seat bullets. It is really easy to tell the difference in pressure when you seat the bullet with an arbor press.

 

[recurveman]

Good point... I had been assmining that once fired brass was a copy of my chamber. But with brass bounce back my shoulder it probably further out then I think.

For example shooting facorey ammo, I get shoulder at .038-.037. How much does the brass bounce back? Possible .001-.002? So my shoulder is actually closer to .040 and I’ve been bumping the should back to .035 which could explain the case lengthiness by .005-.007?


Maybe my chamber isn’t even on the large size of spec, maybe I’m just bumping the shoulder too much.

When fire forming new brass 2-3 times, do I just neck size in between the firings so I don’t bump the shoulder? Side note, I get approx .004” of case stretch when I neck size


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Your brass is going to be really, really close after the first firing. I've done some wildcat fire forming that will push the shoulder out .100 at times and expand the case outwards. If you are worried about the shoulder changing from time to time I would just shoot all your brass and then size them all at once. typically I will only size the entire lot of brass at once. So you will end up keeping track of 1st firing, 2nd firing, 3rd firing. The brass will bounce back a little but not a ton. If it didn't bounce back a little it wouldn't come out of your chamber. It depends on how tight you want to get your tolerances. Normally I push my shoulder back enough to see that it moved so that I know that all of the brass will be the same. Typically .001-.002. It really isn't a bid deal in creating accuracy. Getting every case the same is a bigger deal.

I also noticed that you said the group had a water line of 1" and was 2.5" wide. Typically we look at the water line during load development for a good solid load. Typically the left and rights are caused by the shooter or the environment. A water line that is in the 1/3 -1/4 MOA is pretty good for hunting. Less is always better and your water line will be impacted more by your reloading practices at greater distances.

 

[WestexSBK]

This isn’t my whole process. Just the basic sizing process. I use a powder lubricant in 6 because it helps during the mandrel process. Doing this I get very consistent seating on my KM press.

I love bright, shiny, and freshly annealed cases as much as anybody but it isn’t necessary. I’ve shot thousands of rounds with nothing more than some steel wool on the necks.

The arbor press is without a doubt the best tool I’ve invested into. Highly recommend it to anyone

I do this mostly but I wouldn't put lube inside of my neck at step 6. I only lube the outside of my brass when sizing. At some point in the process you could also use a tumbler or supersonic device to clean the brass if you want. Shiny is always cool!!!!!!!!

The arbor press will totally change how you seat bullets. It is really easy to tell the difference in pressure when you seat the bullet with an arbor press.

 

[recurveman]

This isn’t my whole process. Just the basic sizing process. I use a powder lubricant in 6 because it helps during the mandrel process. Doing this I get very consistent seating on my KM press.

I love bright, shiny, and freshly annealed cases as much as anybody but it isn’t necessary. I’ve shot thousands of rounds with nothing more than some steel wool on the necks.

The arbor press is without a doubt the best tool I’ve invested into. Highly recommend it to anyone

Yeah I normally don't clean my cases either. Just means they are trained properly.

I've almost got to the point where I'm happy buying prepped Nosler brass and let it rip with the rounds that aren't wildcats of some sort. It costs a bit more but it saves me a bunch of time and I haven't noticed enough accuracy change out to 1000 yards where it is worth the time. I do run the mandrel down the neck on new brass though. Plus, at some point cases will need to be annealed to get a consistent neck tension. For that matter Nosler brass is typically done after a few firings anyways because the brass is so soft.

 

[TimberHunter]

*update*

Shot again today at 300 and 400 yards. Both under MOA with a 5mph or so wind so I’m pretty pleased!

But I got two different velocity groups today... I had 7 cases I loaded earlier today and those were around 3000 FPS +- 20 FPS. I also had 3 cases that I loaded 4 days ago that read 3073 and 3090 and error on the last one. The 3 cases from 4 days ago were loaded with the exact same powder (4831 SC), powder charge (58.3), seating depth (3.320”) as the 7 I loaded today but they shot about 80 FPS faster.

I couldn’t tell the difference on the target despite my zeiss hunting app saying there should be 1.1” difference at 400 yards.

The conclusion I came to was that the bullets that were put together 4 days ago experienced a very mild “cold weld”. I’m going to load up a bunch and then wait a few days to shoot them to see if I can replicate what I saw today.

Has anyone experienced higher velocities when shooting cases that had been assembled for a while?


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