Redding bushings

[Quackaddict]

Gentleman, Have a bit of an issue and would like your help resolving it, picked up a Redding FL bushing die and a Comp seater, running Lapua brass in my new 243 varmint rig.

I have come across two ways that you can get the "proper" bushing size and both give me different answers. First, blind math, bullet is .243, and case neck thickness is .11 (tested a lot of ten and found only one that was different by a thousnadth) so we get .243 +.011 +.011 = .265 - .001 = a bushing size of .264.

The other way that I tried was straight off the redding website, I simply measured a loaded case ( actually 5 of them) and all were .270, so using that number you get a bushing size of .269.

Which is correct?

 

[JWV]

Re: Redding bushings

I read in midway that taking a fired casing, measuring the outside diameter of the unsized fired case neck and subtracting the amount of neck tension you want is a good technique.

 

[Victor N TN]

Re: Redding bushings

What brand is the loaded round you checked? Not all brands of brass have the same case neck wall thickness. If I have brass in hand, I do the bullet + wall thickness X 2 = total - .002" for neck tension.

 

[JWV]

Re: Redding bushings

Is the technique I mentioned at all useful Victor. I only ask because I have not tested, just read it.

 

[DBohn]

Re: Redding bushings

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JWV</div><div class="ubbcode-body">Is the technique I mentioned at all useful Victor. I only ask because I have not tested, just read it. </div></div>

If you're shooting a tight neck custom rifle it might work but I wouldn't use it for factory rifles. In factory rifles your brass will most likely be more than a few thousandths too big after firing.

 

[RTH1800]

Re: Redding bushings

I measure loaded rounds and go for .002 NT on a case, and after 6 loadings, I turn the bushing upside down, which adds .0005 NT due the the taper bore of the bushing. Saves buying another bushing.

 

[MitchAlsup]

Re: Redding bushings

In the case mentioned, measuring the assembled case is superior to "measuring necks, doubling them, and adding bullet diameter."

It is what it is.

Another method is to measure neck diameter before seating the bullet and then after.

 

[Victor N TN]

Re: Redding bushings

At no time have I been able to use any data from the outside diameter of a fired case that would help determine neck tension for a specific cartridge. Measuring the wall thickness of a clean and sized case neck and the bullet outside diameter is the only way I have started. You can make adjustments after that. For each caliber that I have a bushing die for I have at least 1 other bushing going larger and 1 if not 2 going smaller. As brass gets older and used more you may have to increase the amount of compression on the neck to get the neck tension you desire.

I think the statement about measuring the fired case may have been a typographical error or other type of incidental mistake.

 

[Quackaddict]

Re: Redding bushings

Alright, right here with my caliper and actual bullets,

Loaded rounds = .271, .272, and .272

Components = Bullets (70 grain blitz) = .243 and .243

Brass (lapua) = .014,.014, .013,.014

Alright, I have figured out my issue, I wasn't using good caliper technique on my first attempt, if you do the math a loaded round and tehoretical measurements of components now are the same.

so assuming total neck diameter is .272 or .271, does a .270 bushing sound correct? Or should I go with a .269?

 

[Brain]

Re: Redding bushings

.269

A ball mic is much better suited for wall thickness measurements but at least you figured out where the discrepancy was.

 

[RTH1800]

Re: Redding bushings

Quack,
You have it figured out now. I notice you tend to want very minimal neck tension. It can be too much of a good thing. What you really need is consistant neck tension. Too little and you will get inconsistant pressure and less accuracy. Good Luck.
RTH

 

[jrbet83]

Re: Redding bushings

.270 is the standard...as i've heard. doesn't mean that's the best for everyone, but sounds like that's the standard (starting point).

what would be the advantage between .269 vs .270

 

[Lumpy Grits]

Re: Redding bushings

All of you math will change as the neck work hardens.......
Respectfully,
LG

 

[Quackaddict]

Re: Redding bushings

.269 sounds logical to me, from what I have gathered minimal neck tension is better than lots of it, and as for work hardening, I plan on starting to anneal after every 4th loading to alleviate this.

 

[SPAK]

Re: Redding bushings

I just started using a redding bushing neck die. For my .30-06 My loaded rounds measure .336 using lapua brass. I purchased .336 .335 and .334 bushings.

I actually ended up using a .336 bushing as it gives me a final neck od of .335".

My necks are turned down to .0145" for a net ID of .306" or NT of .002"

I bought my bushings from Midway, their return policy is top notch. Try a bushing, if it doesn't work or you don't want it anymore, return it.

 

[Lumpy Grits]

Re: Redding bushings

Quack- I wouldn't wait till the 4th loading to anneal.
Respectfully,
LG

 

[Quackaddict]

Re: Redding bushings

Noted lumpy, what kind of interval should I use? 2 firings?

 

[Lumpy Grits]

Re: Redding bushings

That's what I do with my FGMM.
Other brands of brass I don't know.
Respectfully,
LG