What is bushing size?

[bosulli]

I have a Redding .288 marked bushing.

The OD is .500

The with of the bushing wall is .108.

To find the ID - multiply the wall thickness by 2, and subtract that from the OD. You get .284.

Why is a bushing with an ID of .284 marked .288?

 

[SPAK]

Re: What is bushing size?

What is your loaded neck OD and what is the OD of the neck after sizing using that bushing on a fired case??

 

[bosulli]

Re: What is bushing size?

Loaded OD is .291. Wall thickness is .014. Bullet caliber .264.

How does that help reconcile the measured ID of a bushing to what it is marked?

 

[SPAK]

Re: What is bushing size?

It doesn't, but I was curious to see if the bushing is machined to allow for some springback. I have some redding bushings at home, but I haven't ever measured them to see if the exact ID is what the bushing size is as marked. I do know that my sized neck OD is not neccessarily always exact to what the bushing size is but it's usually pretty close, within .001"

I'll go home and meaure my bushings after work, or maybe someone else will chime in. It could be an error from the manufacturer which is always a possiblity. You can always call redding too, they've always been pretty helpful for me when I've called them.

What's the sized OD of a neck using the .288 bushing??

 

[pjparker]

Re: What is bushing size?

Curiosity got the better of me, so I dug out my Redding bushings and Mitutoyo dial caliper and measured the 7 that I have that are not in a die right now.

All seven are consistent with a measured ID of .0015" LESS than the diameter marked on them. (Fourth decimal place is estimated)

My .288 bushing does, in fact, size the neck of a fired case to .288", even though the ID of the bushing itself is .2865". (I just tried it on a FGMM case that had been necked down to .260 Rem several firings ago).

So, it looks like the guys and gals at Redding are doing their homework and allow for brass spring-back. It looks to me like bushings are <span style="text-decoration: underline">marked for the results of their use</span>, rather than what the ID of the hole actually is.

Paul

 

[bosulli]

Re: What is bushing size?

I have always understood that the bushing used should be .001 less than the bullet caliber.

So, per your calculation, the adjustment might already be figured in???

I was off .004 from the marked size. might have been off .0005 off on the wall thickness, but that would make my diff .003.

Maybe I am chasing my tail on this one.

I will assume from here out that the bushing is .0015 less than marked.

If my bullet is .264, and the wall thickness is .014. And I desire to have the ID of the case .001 less than the bullet diameter. What bushing should I use?

BTW, i bought the .288 bushing on the assumption I would neck size the brass out of the box, which I did not. And turn down to .012.

 

[SPAK]

Re: What is bushing size?

When you're selecting the proper bushing size Redding reccomends .001" smaller than the loaded neck diameter as a starting point.

I don't know if they make the ID of the bushing exact to the bushing size. Common sense would think they do. However, knowing that brass has some spring back, It may or may not be smaller.

The other thing is what kind of tool are you measuring with?? Calipers aren't always the most accurate tool to do precise measurements with. Micrometers or even a set of pin gauges would be better if you're trying to measure the ID of the bushing.

If your loaded round OD of the neck is .291 then you would start by using a .290 bushing. I would also get a .289 as well. That's the beauty of using bushing dies is you have control over the neck tension. By it from Midway or Sinclairs. If it doesn't work out you can always return it for credit.

Have you tried sizing with the .288 bushing to see what the OD ends up at?

 

[SPAK]

Re: What is bushing size?

Whoops, just saw paul's post. Thanks for measuring your bushings. That answers a lot of questions.

bosulli, I would get the .290 and .289 bushings to start with. You already have the .288 and if that's too small you can either turn the necks or just return it. I don't reccomend turning the necks more than you have to unless it's for a tight necked chamber.

 

[pjparker]

Re: What is bushing size?

Bosulli -
It is easy to get caught up in the details. Just select a bushing size by what it is marked as, and your loaded round neck OD is the important measurement.

.001 smaller than loaded round neck OD may only be enough neck tension if you are single loading. .002 or .003 smaller may be necessary to ensure that the bullet stays in place for the trip out of the magazine, up the feed ramp and into the chamber.

Frogman77 suggested the same bushings that are in the assortment that I use, and these are the sizes <span style="text-decoration: underline">marked</span> on the bushing.

I think you are over-analyzing and taking a step farther than necessary to achieve the desired result.

Paul

 

[bosulli]

Re: What is bushing size?

Probably am over analyzing.

Just remeasured loaded case neck diameter, and its .2895.

I bought 3 bushings at .288, .287, and .286 in the anticipation of neck turning. The neck walls are consistent at .0125, so I am not going to neck turn.

Without a doubt the .288 is sizing down to small.

I will order a .289 and see what happens.

Thanks for the info.

 

[Clark]

Re: What is bushing size?

I can't measure inside diameters accurately with calipers.
I can't do good handloading without pin gauges.

The same size pin gauge, even if .0001" undersized, will not go in a Redding or Wilson bushing. The next .001" size down will be a go.

This is in contrast with Forster FL dies that are sent back with $10 for neck honing. The result is that the specified honing diameter will be a go with the corresponding pin gauge.

What does it all mean?
Buy yourself some pin gauges for the lathe and mill in your gunsmithing shop, and then buy more for your reloading room. I did.
Here is where you can get a set:
http://www.use-enco.com/cgi/INPDFF?PMPAGE=360&PARTPG=INLMK3&PMITEM=616-8100

 

[bosulli]

Re: What is bushing size?

I am going ahead and getting the pin gauges in anticipation of Santa bringing a lathe and mill. Since I have a combo gunsmith\reloading room, I will only need one set.