I was talking to a friend the other day, and this subject came up.

He said he has read that neck tension IS very important, as low neck tension does not allow the powder to burn before the bullet starts moving, and very high neck tension tends to distorts the neck.

Yesterday he came by with a bag of 308 Winchester Lapua brass.

He said he is contributing to the test he suggested I should run.

The boys here are having all sorts of bets - it never stops!

So I took the Lapua brass - they were 80 cases.

I ran all them through a decapping die that does not size anything.

I segregated them by weight, and selected 25 for each of the following tests.

Sierra 168 Match Kings
RWS 5341 primers
42.0 Varget
Remington 40X, with a Leupold 6.5-20 scope.

100 yards in our indoor range.

1. No sizing at all. The bullet moves freely in the neck.
5, 5-shot groups.

I will size the next lot in 0.001" increments, and repeat.

Anyone wishes to hazard a guess on what the results are going to be?

I am very interested to see the results as I shoot a single shot these days. brian

Many years ago I did a similar experiment.

Although I did experiment with numerous bushings to adjust the neck tension, I settled on .003 because I got the most consistent concentric seating of the bullet.
Because it was so long ago I can't remember if there was any unburned powder due to insufficient neck tension.

The Rifle: Savage 223 Heavy barrel
Stock: Composite
Rifle weight: 18 pounds, stock filled with lead
Trigger: Canjar set trigger 2oz.
Chamber: SAMMI
Twist: 1/9 Moly coated
Bullet: Berger 70 Grain LTB Moly Coated
Rifle Rest: Eagle with rails and micrometer adjustment, Flat plate mounted to front stock to match.
Powder / Charge: H322 21 Grains
Velocity: 2700 fps
Barrel Tuner used to adjust for harmonics

NECK Tension .003
Group Size range. .184-.212

I am not a 'good' shot. To take the human element out of the equation I did not touch the rifle with either my cheek or shoulder upon firing.

Let us know how you do.

quote:

Originally posted by Saeed:
I was talking to a friend the other day, and this subject came up.

He said he has read that neck tension IS very important, as low neck tension does not allow the powder to burn before the bullet starts moving, and very high neck tension tends to distorts the neck.

Yesterday he came by with a bag of 308 Winchester Lapua brass.

He said he is contributing to the test he suggested I should run.

The boys here are having all sorts of bets - it never stops!

So I took the Lapua brass - they were 80 cases.

I ran all them through a decapping die that does not size anything.

I segregated them by weight, and selected 25 for each of the following tests.

Sierra 168 Match Kings
RWS 5341 primers
42.0 Varget
Remington 40X, with a Leupold 6.5-20 scope.

100 yards in our indoor range.

1. No sizing at all. The bullet moves freely in the neck.
5, 5-shot groups.

I will size the next lot in 0.001" increments, and repeat.

Anyone wishes to hazard a guess on what the results are going to be?

I am afraid this going to be shot off the bench, as best as I can shoot.

Already shot 5, 5-shot groups with the billets wobbling in the neck.

I tried different bushings, and for these cases at least, a 0.337” bushing just managed to get the bullet gripped by the neck.

This is going to be my next lot, followed by 0.336, 0.335, 0.334 etc.

This should be interesting. Don't the guys that anneal their necks claim that annealing gives more consistent bullet pull also. You might throw that into the test as well?
C.G.B.

quote:

Originally posted by cgbach:
This should be interesting. Don't the guys that anneal their necks claim that annealing gives more consistent bullet pull also. You might throw that into the test as well?
C.G.B.

Annealed v non annealed

I'm also interested in your findings since they're usually quite scientific.

I've been using about 1 thousandths neck tension on the small cartridges and 2-3 on the big stuff especially with big bullets and slow powders.

Maybe I'm doing all wrong?

Zeke

This could be interesting. Are you measuring velocity or just group size?

I would guess that with no tension you might see some speed and group variation as the bullet can sometimes be pushed into the case when chambered. With increasing tension (and assuming the bullets are not seated into the lands), the speed should increase and be a little more erratic, then if you get enough that the bullets are shaving or distorting when seated you might see groups open up. But a bent bullet can still shoot fine at 100 yards even though its BC is different.

Just accuracy, as in my experience what little velocity difference one might get is no more than one get within a group of shots.

quote:

Originally posted by Saeed:
Just accuracy, as in my experience what little velocity difference one might get is no more than one get within a group of shots.

I'm of the belief that more neck tension/bullet pull the better; like in sizing the case without the expander and seating a bullet into that. The longer you can hold the bullet, the more completely the powder should burn. Uniform neck thickness is of greater concern as far as accuracy goes.

Dundee, Great call sign BTW..!

I agree. One of the very few things I think the government gets right is bullet construction.
They anneal and put a lot of tension on the bullet for obvious reasons.

I used to shoot a fair amount of 45-70 BPCR,
1885 Winchester Highwall. My best results (off the bench) was 1 1/4 inch groups @100 yards with the cases full length resized. I can't remember how much tension that put on the cast bullet but my results were better with a lot of tension.

For those that like Black Powder shooting:
[FLASH_VIDEO]
20 Shots 1 1/4" Group sans first fouling shot from a clean barrel

Browning 45-70 M78
72 Grain Swiss #4 (1 1/2 F) Compressed .12"from a 36" Drop Tube
515 GR.Brooks Mould Government #457125 20/1 Lead/Tin
Custom Lube / Wax Wad
Cases Full length sized
Federal Gold Match 150M Pistol Primers
Avg. Velocity 1205 fps

Interestingly on 1/2 (10 of the rounds) were taper crimped .002 and the other half used NO crimp. (although I think the full length sizing provided the required neck tension)

quote:

Originally posted by ANTELOPEDUNDEE:

quote:

Originally posted by Saeed:
Just accuracy, as in my experience what little velocity difference one might get is no more than one get within a group of shots.

I'm of the belief that more neck tension/bullet pull the better; like in sizing the case without the expander and seating a bullet into that. The longer you can hold the bullet, the more completely the powder should burn. Uniform neck thickness is of greater concern as far as accuracy goes.

For neck turning I've switched to using the Sinclair NT-1000 tool. You FL size the case with no expander. For say a 6.5mm you expand the neck using a .263 mandrel [I opted for the carbide version]. The turner pilot is sized a .262. I wish they would offer mandrels in .261 and/or .260 or smaller for those that like more neck tension when they reload the turned cases. Having my turner all setup I'd just as soon not use the .262 mandrel. I suppose I could always buy another a $50 a pop. Redding however advises not having a lot of neck tension when you use their competition seating dies.

A writer in one of the gun mags I subscribed to about 30+ years ago recommended reducing the size of the expander. I reduced the expander .001 on a 44 mag and got excellent accuracy. The case did show a bulge where the bullet was seated. One thing I noticed was I had to reduce the powder charge by 1/2 to 1 grain. I think I was using 296.

quote:

Originally posted by Jgrabow6493:
A writer in one of the gun mags I subscribed to about 30+ years ago recommended reducing the size of the expander. I reduced the expander .001 on a 44 mag and got excellent accuracy. The case did show a bulge where the bullet was seated. One thing I noticed was I had to reduce the powder charge by 1/2 to 1 grain. I think I was using 296.

The last time I loaded .357 mag ammo with 296 powder I used a full Redding profile crimp. Never noticed any need to reduce the load. IIRC they recommend not to reduce loads with WW296.

Any suggestions on how tight I should go?

0.337 was the largest Redding button that started to tighten the next slightly.

0.338 the case necks were loose.

I have done 0.337, 0.336, 0.335, 0.334 so far.

The targets are still down range on the target board, but from the looks of things nothing drastic has happened.

quote:

Originally posted by ANTELOPEDUNDEE:

quote:

Originally posted by Jgrabow6493:
A writer in one of the gun mags I subscribed to about 30+ years ago recommended reducing the size of the expander. I reduced the expander .001 on a 44 mag and got excellent accuracy. The case did show a bulge where the bullet was seated. One thing I noticed was I had to reduce the powder charge by 1/2 to 1 grain. I think I was using 296.

The last time I loaded .357 mag ammo with 296 powder I used a full Redding profile crimp. Never noticed any need to reduce the load. IIRC they recommend not to reduce loads with WW296.

We are not talking crimps. I crimped the 44 mag before reducing the expander as well as after reducing the expander. Reducing the expander caused excessive pressure with the load I had been using that previously showed normal pressure.

quote:

Originally posted by Saeed:
Any suggestions on how tight I should go?

0.337 was the largest Redding button that started to tighten the next slightly.

0.338 the case necks were loose.

I have done 0.337, 0.336, 0.335, 0.334 so far.

The targets are still down range on the target board, but from the looks of things nothing drastic has happened.

What's the case neck ID if you size without an expander. Unless you have access to a machine shop, that's about as tight as you can practically go.

I don't think the amount of neck tension affects accuracy as much as variations in neck tension. When I found an accurate load in my hunting rifles I used to load up 100 rounds or so. When sighting in one of my rifles for an upcoming hunt, the rifle was shooting about 3 MOA when it had previously shot 1MOA with the same lot of reloads which were more than 5 years old. Loaded up some new reloads with the same recipe and it was back to 1 MOA. My theory is that the bullets were sticking in the necks and causing wide variations in pressure.Now I only load batches that will be shot in a year or so.

quote:

Originally posted by Jgrabow6493:

quote:

Originally posted by ANTELOPEDUNDEE:

quote:

Originally posted by Jgrabow6493:
A writer in one of the gun mags I subscribed to about 30+ years ago recommended reducing the size of the expander. I reduced the expander .001 on a 44 mag and got excellent accuracy. The case did show a bulge where the bullet was seated. One thing I noticed was I had to reduce the powder charge by 1/2 to 1 grain. I think I was using 296.

The last time I loaded .357 mag ammo with 296 powder I used a full Redding profile crimp. Never noticed any need to reduce the load. IIRC they recommend not to reduce loads with WW296.

We are not talking crimps. I crimped the 44 mag before reducing the expander as well as after reducing the expander. Reducing the expander caused excessive pressure with the load I had been using that previously showed normal pressure.

Unless you were over the ragged edge of maximum load, tight necks and heavy crimps are usually a good thing with WW296 and jacketed bullets.

Saeed,
I use Lapua brass exclusively in my 308s. One thing that struck me about your initial post is that you said the bullets slid freely in the necks of the Lapua brass. My first question is, was this new brass or once fired brass? If the brass is new then those bullets should not have slid freely when you seated them. My new Lapua brass measures .304 outside diameter and provides plenty of tension. How ever when i neck size i also go back with a.304 bushing. IN experimenting with several calibers, 308, 7mm and 264 i have found that neck sizing the neck for consistent tension always yields more accuracy. For example, in my 260AI and my 264 Win mag i use a .288 bushing. I neck size both new brass and fired brass to the same dimension. I keep every target i shoot and can go back and look at what has worked and what has not and it is clear that neck sizing slightly tighter yields more accuracy in my rifles.
You mentioned that you loaded Varget in your 308, over the last couple of years i have gotten away from Varget for a couple of reasons, usually Varget is slower than 4064 and also i do not get the accuracy from Varget i get with 4064 (IMR version). If you have 4064 you might try it and see if it yields different results. I know 4064 is not one of the temp resistant powders but it has peoven its worth to me from temps from 80 down to 20 degrees. MY standard load is 46gr of 4064 with Lapua brass and Fed 210 primers or 210 Match primers. Obviously you might want to start at 45 gr. I start all my bullets at just kissing the lands and usually my best accuracy comes with the bullet seated .005 to .015 off the lands...your rifle may vary.
Obviously they are just suggestions but you might try them. I would be interested to know if your results mimic mine.
Bill

quote:

Originally posted by ANTELOPEDUNDEE:

quote:

Originally posted by Jgrabow6493:

quote:

Originally posted by ANTELOPEDUNDEE:

quote:

Originally posted by Jgrabow6493:
A writer in one of the gun mags I subscribed to about 30+ years ago recommended reducing the size of the expander. I reduced the expander .001 on a 44 mag and got excellent accuracy. The case did show a bulge where the bullet was seated. One thing I noticed was I had to reduce the powder charge by 1/2 to 1 grain. I think I was using 296.

The last time I loaded .357 mag ammo with 296 powder I used a full Redding profile crimp. Never noticed any need to reduce the load. IIRC they recommend not to reduce loads with WW296.

We are not talking crimps. I crimped the 44 mag before reducing the expander as well as after reducing the expander. Reducing the expander caused excessive pressure with the load I had been using that previously showed normal pressure.

Unless you were over the ragged edge of maximum load, tight necks and heavy crimps are usually a good thing with WW296 and jacketed bullets.

My loads were max loads and were not over the ragged edge when using the standard RCBS expander. When I reduced the size of the expander then the loads went over the ragged edge. Evidently, increasing the neck tension also increases pressures.

OK, here is my results so far, and I will continue with another 2 or 3 sizings.

No sizing at all. Bullet moves freely in the case neck, average of 5, 5-shot groups, then sized 0.001 down, and so on.

0.464
0.352
0.512
0.420
0.398
0.430

Got a message asking about my method of testing.

The brass was once fired brought here by a friend, made by Lapua.

I cleaned the brass in steel pins and a tumbler.

Decapped using a Lee Universal deprimer.

Cases were then trimmed, primer pockets uniformed, and weighed.

Each group of 5 are as close to each other by weight as possible, all within less than 0.5 a grain.

First lot were loaded and shot.

Using Redding neck sizing buttons, 0.338 fit the necks without sizing - I could put the button over the necks by hand and remove it.

First sizing is with 0.337”.

For subsequent firing the above was repeated with the fired cases, except for cleaning and trimming.

I hope this is clear.

Any questions are welcome.

Good test.
Did the point of impact change between the different neck tensions?
Thanks!

Different lpads, different rifles some like neck tension some dont.

quote:

Originally posted by Dead Eye:
Good test.
Did the point of impact change between the different neck tensions?
Thanks!

No.

I will post all the targets once I am done.

Doesn't seem to be a lot of difference. Any idea how much velocity was affected?

quote:

Originally posted by ANTELOPEDUNDEE:
Doesn't seem to be a lot of difference. Any idea how much velocity was affected?

Having done a few tests in the past, I would assume the velocity difference is negligible.

quote:

Originally posted by Saeed:

quote:

Originally posted by ANTELOPEDUNDEE:
Doesn't seem to be a lot of difference. Any idea how much velocity was affected?

Having done a few tests in the past, I would assume the velocity difference is negligible.

That would be supported by the POI not changing.

You know, point of impact change due to velocity was thrown out of the window with a 22-243 I built.

Velocity difference between shots was over 150 FPS, but the 5 shot groups were so small I had difficulty measuring them!!

I could not understand it at all.

Now, to the other extreme, shooting 22 rim fire at 100 yards, sometimes I can clearly see the lower velocity shots landing lower on the target!

quote:

Originally posted by Saeed:
You know, point of impact change due to velocity was thrown out of the window with a 22-243 I built.

Velocity difference between shots was over 150 FPS, but the 5 shot groups were so small I had difficulty measuring them!!

I could not understand it at all.

Now, to the other extreme, shooting 22 rim fire at 100 yards, sometimes I can clearly see the lower velocity shots landing lower on the target!

I expect that a velocity difference of over 2000 fps at POI might explain that. Time Of Flight is much shorter for the faster bullet so gravity has less time to act on the projectile. 150 fps apparently isn't sufficient enough to provide a visible difference, tho it might be at lower velocities.

I think if you want to see what variation would be introduced you need to shoot several groups using one of each of your neck diameters bushings - i.e. first shot of the group a cartridge with the bullet loose in the neck, next shot of the group the cartridge necked down .001 etc.; then compare the group sizes to the group sizes you are getting with all cartridges of a group with the same neck tension.
This would show what effect having widely different neck tensions would have on your group size.

quote:

Originally posted by CMcDermott:
I think if you want to see what variation would be introduced you need to shoot several groups using one of each of your neck diameters bushings - i.e. first shot of the group a cartridge with the bullet loose in the neck, next shot of the group the cartridge necked down .001 etc.; then compare the group sizes to the group sizes you are getting with all cartridges of a group with the same neck tension.
This would show what effect having widely different neck tensions would have on your group size.

A great idea.

I will do that after I am done with going down 0.001" at a time.

I will go down to 0.330".

Then I will do this.

I am sure I have tried 0.001, 0.002, and up to 0.003 inch neck tension at some times.

As has been an AR Reloading Commandment since I re-started reloading " Consistency in reloading produces the best results. "

Thank you Saeed, for what looks to have been a very interesting test to carry out.

From where l sit and a very quick look over the targets, it would seem that what l have been reading over the years may well be true, in that both camps of thought are right, meaning very little neck tension is required for benchrest shooting to be accurate (.001' tension, all rounds inside each group and very little vertical dispersal), and that if you wish to go out and not fear your precious reloads not come apart then a higher neck tension will also yield good accuracy (.006' +.008' show very good promise and l would count the poor single group for the .007' as a "flier" or pulled shot)

Thank you, Saeed!

Looks like I don't need a series of expander buttons.

quote:

Originally posted by Samuel_Hoggson:
Thank you, Saeed!

Looks like I don't need a series of expander buttons.

The "buttons" should be thrown in the trash can. Use a mandrel with a tapered end to keep the necks straight even if you need to expand as a separate step.

Very interesting Saeed.

Because of the small and large groups in some of the samples, have you considered doing a Standard Deviation of the group sizes?

O neck tension:

Population standard deviation: 0.16996234877
Sample standard deviation: 0.19002368273
Population variance: 0.0288872
Sample variance: 0.036109
Mean: 0.464


.004 Neck tension

Population standard deviation: 0.10033464008
Sample standard deviation: 0.11217753786
Population variance: 0.01006704
Sample variance: 0.0125838
Mean: 0.3984

quote:

Originally posted by ANTELOPEDUNDEE:
The "buttons" should be thrown in the trash can. Use a mandrel with a tapered end to keep the necks straight even if you need to expand as a separate step.

Thanks. I float the decap/expander rod using a rubber grommet. The button is somewhat tapered, but carbide.