Neck bushing help

[PBking51]

I am new to the neck sizing game with my 300 wsm. This is for a hunting set up in a CA ridgeline, so I am using a forster bump /neck bushing die and Norma Brass. The only bushing I have for it is .333 at the moment. I am bumping the shoulder .002 back.
A 1x fired case from that gun has a neck is measuring .340
The one method says subtract .002 from a fired neck diameter and that's about the size bushing I need.
The other method has me measuring neck wall thickness x2 + .308 for the bullet and subtract .002 . Neck wall thickness is .015.

This indicates a .338 in method 1 and .336 in method #2.

Being that all I have on hand is a .333 what can I expect using this bushing? Will I just have to trim brass more frequently by technically over sizing the neck ? Or is there a degree of accuracy lost by doing this by having increased neck tension? Would I be better suited by purchasing a 338 and 337 bushing?

 

[1911nut]

You’ll over work your brass with the .333 bushing.

Brownells Gun Tech™ Tip: There are two ways to select the steel neck bushings you need: (1) Measure the outside neck diameter of your loaded cartridge and subtract .002" to .003". This allows approximately .001" of brass to spring back for correct neck tension. (2) You can also measure the neck wall thickness of your case, multiply by two, add the diameter of your bullet and subtract .002" to .003".

 

[PBking51]

You’ll over work your brass with the .333 bushing.

Brownells Gun Tech™ Tip: There are two ways to select the steel neck bushings you need: (1) Measure the outside neck diameter of your loaded cartridge and subtract .002" to .003". This allows approximately .001" of brass to spring back for correct neck tension. (2) You can also measure the neck wall thickness of your case, multiply by two, add the diameter of your bullet and subtract .002" to .003".

So besides overworking the brass and shortening their number or loadings, does it affect accuracy ?

 

[acloco]

So besides overworking the brass and shortening their number or loadings, does it affect accuracy ?

Yes, it can. May also help as well.

The "just right" neck tension - the quest of the reloader that is loading for accuracy and REPEATABLE accuracy.

 

[Bill Norris]

I am new to the neck sizing game with my 300 wsm. This is for a hunting set up in a CA ridgeline, so I am using a forster bump /neck bushing die and Norma Brass. The only bushing I have for it is .333 at the moment. I am bumping the shoulder .002 back.
A 1x fired case from that gun has a neck is measuring .340
The one method says subtract .002 from a fired neck diameter and that's about the size bushing I need.
The other method has me measuring neck wall thickness x2 + .308 for the bullet and subtract .002 . Neck wall thickness is .015.

This indicates a .338 in method 1 and .336 in method #2.

Being that all I have on hand is a .333 what can I expect using this bushing? Will I just have to trim brass more frequently by technically over sizing the neck ? Or is there a degree of accuracy lost by doing this by having increased neck tension? Would I be better suited by purchasing a 338 and 337 bushing?

Being that all I have on hand is a .333 what can I expect using this bushing? Will I just have to trim brass more frequently by technically over sizing the neck ? Or is there a degree of accuracy lost by doing this by having increased neck tension? Would I be better suited by purchasing a 338 and 337 bushing?

U will over work the brass by neck sizing it down too much. Not sure it will affect the trimming process at all. There is a certain degree of accuracy to be gain by adjusting neck tension BUT it's not the case that there is too much neck tension in every situation.

 

[1911nut]

.015 x 2 + .308 = .338

i would be trying a .336 and a .335 bushing.

that would give .002” and .003” neck tension

 

[PBking51]

Yes, it can. May also help as well.

The "just right" neck tension - the quest of the reloader that is loading for accuracy and REPEATABLE accuracy.

So I may benefit for more neck tension or less neck tension and the only way to truly know is test the same load with different neck tension?

 

[Bill Norris]

Correct.

 

[newbieshooter]

this happened to be in today's bulletin:

Choosing the Best Neck Bushing Size — Tips from John Whidden « Daily Bulletin

Whidden Gunworks makes great sizing and seating dies. The Whidden full-length sizing die with neck bushing is very popular because it allows you to tune the neck tension by using different bushings, with larger or smaller inside diameters.

bulletin.accurateshooter.com

 

[jepp2]

So besides overworking the brass and shortening their number or loadings, does it affect accuracy ?

It can in two ways.

1. Are you using an expander? If yes, and you undersize your neck with too small of a bushing, when the expander pulls back through the case neck, it WILL pull the neck off center (thus negatively affecting case neck TIR).

2. If you reduce the case neck too much in one step - using too small a bushing, in some cases, the neck will come out several thousandths smaller than the bushing. I have personally experienced this, and it is covered on the Redding website as well. Here are their words:

It has come to our attention through customer calls and our own use of the bushing style sizing dies that in certain instances, a given neck sizing bushing will produce a case neck diameter that can be several thousandths of an inch smaller than the actual diameter of the bushing. This idiosyncrasy occurs when the neck diameter of the fired case is a great deal larger than the diameter of the neck sizing bushing, such as occurs when factory chambers are on the large side of the tolerance range and the brass is on the thin side. Typically, we have not noticed any problems until the case neck is reduced more than 0.008-0.010".

Found here: https://www.redding-reloading.com/tech-line-a-tips-faqs/140-bushing-selection

 

[PBking51]

I am reducing the diameter .007 with the .333
I tried 1 and there's no resistance when raising the die off the case. (I am using an RCBS summit)

 

[243winxb]

300 wsm

Heavy recoiling cartridges may need more neck tension, bullet hold then .002" ? After firing, check the last round in the magazine for bullet movement.


As said, measure a loaded rounds neck diameter with a micrometer.

 

[D-4297]

The OP said this was for a Hunting usage , so we need to consider that when offering advice . What we use on the Range is generally not applicable to hunting practices , such as jamming into the lands , and lighter neck interference dimensions . Personally ; I would suggest he go with a .003 - .004 interference fit , and make sure his bullet has a slight "jump" , maybe .005 - .010 , so as not to have any issues "pulling a bullet out of the case" , if he has to extract a round in the field . It may have a affect on long range accuracy , but it would probably be minimal , at best .

 

[PBking51]

I'm starting out 20k from jam and working back in .003 increments until I find some nodes. I kind of want to size one in a FL die and see what the neck is. For comparison all of my hunting reloading has been above factory offerings but now I just want to play with necks and see if I can get tighter groups so I feel better taking shots at 5-600 with this hunting rig

 

[Coyotefurharvester]

Or you can measure the neck on a finished round and subtract 0.002,3,4 whatever interference fit you want = bushing size. Or full length size without the expander and use a mandrel or pin gage to expand I.d. of neck for fit.- 0.0025-0.003 of loaded/seated diameter would be a starting point for a larger hunting caliber round. I prefer no expander.

 

[divingin]

A 1x fired case from that gun has a neck is measuring .340
The one method says subtract .002 from a fired neck diameter and that's about the size bushing I need.

That method is largely useless. It depends on all chamber necks being the same (they're not.)

As an example, if a chamber has a neck diameter of .342, you'll get somewhere around your measurement of .340 on the brass after firing. If a different rifle has a neck diameter of .346, the brass will come out measuring 344-345. Subtracting 2 thou as the bushing size will likely end up with brass that will not hold the bullet at all.

You can approximate what you'd get out of a standard FL sizing die by measuring the expander ball and subtracting a thousandth or two (the die sizes the neck quite small, then the expander opens it up as the case is withdrawn; the subtraction is springback.)

The advantage of the bushing die over a standard FL die is that you can easily adjust your final diameter (assuming you have the bushing to do so, which it sounds like you don't.)

 

[PBking51]

That method is largely useless. It depends on all chamber necks being the same (they're not.)

As an example, if a chamber has a neck diameter of .342, you'll get somewhere around your measurement of .340 on the brass after firing. If a different rifle has a neck diameter of .346, the brass will come out measuring 344-345. Subtracting 2 thou as the bushing size will likely end up with brass that will not hold the bullet at all.

You can approximate what you'd get out of a standard FL sizing die by measuring the expander ball and subtracting a thousandth or two (the die sizes the neck quite small, then the expander opens it up as the case is withdrawn; the subtraction is springback.)

The advantage of the bushing die over a standard FL die is that you can easily adjust your final diameter (assuming you have the bushing to do so, which it sounds like you don't.)

Well I visited Whidden's sight and saw their posted measurements for their FL dies, and their 30 cal dies are significantly tighter than .333 bushing and my rcbs FL die sizes the neck to .336. With that being said I stand to belive that .333 will work, but without having say a .335 and .338 bushing, I will never know what my gun prefers with Norma Brass. I realize no matter how I size my necks , once the same bullet is seating in each diameter they will all yield the same OD but will have higher or lower tension on the neck. This is why I wanted to see what FL dies would produce, because I have yet to have a worked handled using FL dies that doesn't get me Sub MOA (@100yards).

Would change in neck tension affect all groups at longer distance than 100 yards? And if it's all relative, would a good load with more or less neck tension have the powers to shrink a .5 group to a .35 size group? Or is it something that will be measured in .0001 increments where only noticeable past 500 yards?

And update: so I have .333 bushing in hand and .335,.336,.337, and. 338 in a virtual shopping cart. I think for the application and the caliber, I am probably safe getting .335 and .337 as I have 300+ piece of new Norma brass and 200 1x fired

 

[dkhunt14]

Well I visited Whidden's sight and saw their posted measurements for their FL dies, and their 30 cal dies are significantly tighter than .333 bushing and my rcbs FL die sizes the neck to .336. With that being said I stand to belive that .333 will work, but without having say a .335 and .338 bushing, I will never know what my gun prefers with Norma Brass. I realize no matter how I size my necks , once the same bullet is seating in each diameter they will all yield the same OD but will have higher or lower tension on the neck. This is why I wanted to see what FL dies would produce, because I have yet to have a worked handled using FL dies that doesn't get me Sub MOA (@100yards).

Would change in neck tension affect all groups at longer distance than 100 yards? And if it's all relative, would a good load with more or less neck tension have the powers to shrink a .5 group to a .35 size group? Or is it something that will be measured in .0001 increments where only noticeable past 500 yards?

And update: so I have .333 bushing in hand and .335,.336,.337, and. 338 in a virtual shopping cart. I think for the application and the caliber, I am probably safe getting .335 and .337 as I have 300+ piece of new Norma brass and 200 1x fired

Alot of my guns like a fair amount of tension. Usually I run .002 or .003. In a hunting gun I like tension, recoil and loading and unloading can move bullets. In my WSM at 1000 yards, it seems to prefer good tension. My Dasher seems the same. After a certain amount, the gain is only proportional. If it was me I would remove the .337 and .338 from the cart. To me they wouldn't give enough tension for a WSM and for hunting loads. Matt

 

[PBking51]

UPDATE:

I used 64 grain of Hybrid 100v to get a 4 shot string of 180gr sciroccos to shoot 2995 fps and a SD of 2.25. Below is the group I shot. Dot is a hair over 2.5" and center dot is 1". Should I bother decreasing neck tension or will I just loose that SD and some velocity? Bullets seated 4 thousandths off lands.

 

[Ccrider]

For my hunting load, I start at safe pressure and work up until I start seeing pressure. I work from touch back out of the lands because I know I will be extracting the loads after the hunt. After I find an acceptable load, I play with neck tension but would never go under .003 with a hunting rifle. I don’t want to create unnecessary problems on a hunt.