Neck Bushing Sizing

[Jesse Jaymes]

I have been waiting for a question like this.

Please get back with us when you get a bushing and report.

I have hundreds of dollars in schitt bushings. Subtracting .001" from a loaded round will NOT EVEN HOLD A BULLET.

Spring back in brass, inconsistencies, etc will vary greatly.

Those that stated STARTING at -.003" are the most accurate.

I'll wait

 

[Jesse Jaymes]

Differences in SAC bushings and Redding bushings are enough to make your head spin. This weekend loading 6.5 Creed in Hornady brass.

A new .290" SAC bushing was not enough neck tension to hold a bullet. But a .291" Redding bushing was.

Stop pissing around attempting to measure neck wall thickness. Squish the bullet in the brass and measure. Subtract at minimum .003" and be ready for disappointment.

 

[eoperator]

Differences in SAC bushings and Redding bushings are enough to make your head spin. This weekend loading 6.5 Creed in Hornady brass.

A new .290" SAC bushing was not enough neck tension to hold a bullet. But a .291" Redding bushing was.

Stop pissing around attempting to measure neck wall thickness. Squish the bullet in the brass and measure. Subtract at minimum .003" and be ready for disappointment.

Annealing will greatly help with this type of irritation. If you do not anneal, regular non bushing type dies or -.005 bushings

 

[SDHNTR]

Differences in SAC bushings and Redding bushings are enough to make your head spin. This weekend loading 6.5 Creed in Hornady brass.

A new .290" SAC bushing was not enough neck tension to hold a bullet. But a .291" Redding bushing was.

Stop pissing around attempting to measure neck wall thickness. Squish the bullet in the brass and measure. Subtract at minimum .003" and be ready for disappointment.

This is pretty much it. Measuring is wasting your time since there is no uniformity. .290 measured on your caliper doesn’t mean .290 in anyone’s bushing. And .290 in one company’s bushing is not .290 in another’s. Things can vary by several thou. IME, there’s no way around this other than experimenting. Which is why I stated what I do. I buy a few Redding bushings around the measurement I think I “should” have and try them. Then, if I want to upgrade to an SAC bushing I buy one .001” smaller than the Redding that worked and it puts me right where I need to be. I’ve done this now several times and it works for me.

 

[BrBa]

so I’m measuring an average of 0.01675” neck wall thickness across a random pull of 12 cases from 100 pieces of new starline brass. Granted I’m using calipers and not a ball mic so that could be causing in accurate readings. My largest wall thickness was 0.017” and thinnest was 0.0155 most measured at 0.0165.

Those measurements will decrease when using a ball mic. 0.0165 neck walls seems very thick depending on manufacturer. My Lapua brass measured 0.015 to 0.016 when new. Alpha 0.014 to 0.015.

 

[JollyRogers]

This is pretty much it. Measuring is wasting your time since there is no uniformity. .290 measured on your caliper doesn’t mean .290 in anyone’s bushing. And .290 in one company’s bushing is not .290 in another’s. Things can vary by several thou. IME, there’s no way around this other than experimenting. Which is why I stated what I do. I buy a few Redding bushings around the measurement I think I “should” have and try them. Then, if I want to upgrade to an SAC bushing I buy one .001” smaller than the Redding that worked and it puts me right where I need to be. I’ve done this now several times and it works for me.

This is what I’m planning to do, was measuring just to have a starting place as I don’t want to buy the full range of suggested 7mm-08 bushings (.304-.312).

 

[JollyRogers]

So spoke with Hunter at Starline and he confirmed that ball mics are necessary and that I should chamfer the necks prior to measuring.

Got some ball mics and chamfered a random selection of 12 pieces of brass and averaged 0.0137” neck wall thickness. So 3-4 thou thinner than calipers…. The more you know!

Now that gives me a starting place of a .308” bushing for 3 thou neck tension.

I’m planning to buy 3 bushings should I bracket that dimension and go .307”, .308”, and .309”?

 

[Mulyhuntr]

So spoke with Hunter at Starline and he confirmed that ball mics are necessary and that I should chamfer the necks prior to measuring.

Got some ball mics and chamfered a random selection of 12 pieces of brass and averaged 0.0137” neck wall thickness. So 3-4 thou thinner than calipers…. The more you know!

Now that gives me a starting place of a .308” bushing for 3 thou neck tension.

I’m planning to buy 3 bushings should I bracket that dimension and go .307”, .308”, and .309”?

I'd just try a 309 to start

 

[BrBa]

I might not even buy a .309 bushing unless you plan to buy different brass in the future. If you start with -.003 the brass will spring back to @ -.002.

 

[JollyRogers]

I might not even buy a .309 bushing unless you plan to buy different brass in the future. If you start with -.003 the brass will spring back to @ -.002.

That’s along the same line of thought I was having, almost seems better to go .306, .307, .308

 

[Jesse Jaymes]

@JollyRogers So......what bushing worked?

 

[JollyRogers]

@JollyRogers So......what bushing worked?

Just got the bushings in Monday .306, .307, .308 and only got to play with setting my die up for about an hour. Hopefully will have time next week to get a real update to post.

 

[WTNUT]

Lots of good information here, but watching this from a far it is like watching the tower talk a passenger down as he lands a 737 after both pilots pass out.


Sent from my iPad using Tapatalk

 

[wind gypsy]

Lots of good information here, but watching this from a far it is like watching the tower talk a passenger down as he lands a 737 after both pilots pass out.

haha. Ideally the below would have been the first response and then the OP followed it. It took me a minute to step back and realize that the OP is in the "dicking around and working to understand how and why all this stuff works" stage of reloading. A lot of folks answering probably forgot about that stage.

Stop pissing around attempting to measure neck wall thickness. Squish the bullet in the brass and measure. Subtract at minimum .003" and be ready for disappointment.

 

[JollyRogers]

haha. Ideally the below would have been the first response and then the OP followed it. It took me a minute to step back and realize that the OP is in the "dicking around and working to understand how and why all this stuff works" stage of reloading. A lot of folks answering probably forgot about that stage.

This is exactly the stage I am in; trying to consume and understand a ton of information. In hindsight I should have bought a regular (non bushing) FL die to start as I did not realize the added complication a bushing die would introduce.

I do appreciate everyone’s input and follow ups.

 

[Jesse Jaymes]

No. You should learn neck bushings and advanced reloading. The pissing around part is the ball micrometers, annealing, neck trimming, etc.

Squish the bullet in the brass and measure.

I am still interested in the answer.

There's one more hint....most of what you'll learn will be by feel on the ram while seating a bullet....not a micrometer.

 

[Elkslut]

Use the proper measuring devices. If you want to measure thousandths (.001) use a micrometer. If you are ok with + or - .01 use calipers. Remove burrs, measure more than one place.

 

[leclairk]

When people talk about finding the right bushing that works for you, are you speaking to group sizes or low SDs? There are so many variables to group size I'm trying to understand how I would know what is causing what. If I decide to go with a bushing that's .003 smaller, I work up a load with that bushing that gives me low SDs and groups well, why would I ever mess around with different bushings? At what point in load development are messing around with bushings?

 

[Castle Rock]

This is exactly the stage I am in; trying to consume and understand a ton of information. In hindsight I should have bought a regular (non bushing) FL die to start as I did not realize the added complication a bushing die would introduce.

I do appreciate everyone’s input and follow ups.

It isn’t hard if you think less, all you need is adequate neck tension

When people talk about finding the right bushing that works for you, are you speaking to group sizes or low SDs? There are so many variables to group size I'm trying to understand how I would know what is causing what. If I decide to go with a bushing that's .003 smaller, I work up a load with that bushing that gives me low SDs and groups well, why would I ever mess around with different bushings? At what point in load development are messing around with bushings?

See above, neck tension that will hold a bullet securely but not enough to shave the jacket is what you are after

 

[Harvey_NW]

When people talk about finding the right bushing that works for you, are you speaking to group sizes or low SDs? There are so many variables to group size I'm trying to understand how I would know what is causing what. If I decide to go with a bushing that's .003 smaller, I work up a load with that bushing that gives me low SDs and groups well, why would I ever mess around with different bushings? At what point in load development are messing around with bushings?

Most of them probably don't even know because their findings are based on small samples. To say that a certain bushing is better than another would need to be substantiated with a valid sample size that most aren't willing to shoot. But there are guys like Alex Wheeler that are testing in match format, so 20 shots, that say .004/5" interference repeatedly has up to half the amount of vertical that .002" does at 1k yards, in many cartridges.

I would imagine the difference in interference would have less of an impact on velocity than the variation in thickness of unturned necks, and I believe expanding the necks with a mandrel or button is beneficial to shrinking ES/SD. I would imagine that the difference in interference also doesn't affect dispersion as much as most believe it may.