Redding bushing Undersizes. Why????

[rchouser]

I am neck sizing 260 Rem Brass using an RCBS Bushing Die and a Redding .290 Bushing. My sized necks are reading .288 using a caliper measurement on the neck. I would have expected .291 or something (with spring back). I am confused by the .288 reading. My pre-sizing necks measure .295 so the Redding Bushing is working. Again, I am confused. I am new to bushings, so maybe this is normal, but, not intuitive.
thanks rc

 

[bigedp51]

rchouser

Neck thickness, age and how hard-soft the brass effects spring back also, what does a new virgin cartridge size to? What does a different manufacture-name brand size to?

Humor
In vehicle front end crash tests at 35 mph "how" the front end of the car is constructed determines the cars overall length at the end of the test.

 

[rchouser]

I agree that my caliper is not as good as a micrometer. I checked my caliper by running it against 3 different custom bullet calibers. My caliper is correctly calibrated (it is manual dial not digital).

I did not know that the measurement printed on the Redding Bushing was an estimate. This would be the best explanation because it is sizing under.

I will look for the bushing die thread that you reference.

I am trying to get the Redding Tech guys on the phone. I want their take on this as well. I am not using any expander with this die setup.

thanks for the input. rc

 

[rchouser]

I know that I am answering my own thread again, but, I found this article on the bushing issue and it is pretty good. Link: http://riflemansjournal.blogspot.com/2009/10/reloading-neck-tension.html

thanks rc

 

[RonAKA]

My Forster 0.267 bushing produces necks that are about 0.2685. However I am using an expanding ball which opens them up about 0.0003". So, without the ball perhaps 0.2682" or 0.0012" larger than the bushing. As close as I can measure the bushing with a caliper it really is about .267. Can't read the caliper to tenths.

 

[fdshuster]

Very few of my neck bushings, both Redding and Wilson, actually size the case neck O.D. to the stamped ident dimension. Most are .001" to .002" smaller. I have to keep a "correction" chart with each set of bushings to determine what the sizing diameter really is. I also have a few that will size out-of-round, all verified with a micrometer. As to the reason why? Have no idea.

 

[rchouser]

This is why this forum is so valuable. Great Information.
I am sizing from a fired neck of .2950 to a sizing bushing of .290 My sized neck is showing up as .2880
The target change is .005 which is inside the change described as being a problem in the "CatShooter" response.

With my brass thickness, I need to have my finished neck size at .2865 (.002 neck tension). I realize that this will be another step down from the .288 produced by my .290 bushing. I may need to buy two new bushings and put the .290 into my parts box. I want to check for runnout before I decide to keep using the .290 as a step bushing.

I started this thread because I wanted to understand what and why the .290 was going to .288 It wasn't intuitive. thanks for all the help
rc

 

[ReedG]

I've been using Redding and Wilson bushings for years and never had the phenomena you describe. I have sized hundreds of 6BR brass to 22BR by just running them into a .246 bushing. The resized necks are all .2455 to .246. My brass is annealed often.

A few years ago, on one of these forums, there was a thread that alluded to the fact that the if the bushing in put in "upside down" it necks smaller. In a couple of nonscientific tests, that seems to be true with my bushings. When the number is down, it sizes correctly; when it is up it sizes about .001 smaller.

I also get better results by screwing the top stem down against the bushing and then backing it off a couple thou to let the bushing be free to align properly.

 

[GermanS1]

RC, the article on neck tension from my website that you linked above is useful, but you may also want to read this one on two-step sizing with bushing dies. http://riflemansjournal.blogspot.com/2010/04/reloading-two-step-sizing-and.html

The problem you're seeing is from trying to resize more than 0.004" with a bushing. Beyond that amount, they begin to actually taper the neck a bit and do not yield the marked size. Try the two-step method and I think you'll find that the second step outd you right on the number.

 

[RonAKA]

I am sizing from a fired neck of .2950 to a sizing bushing of .290 My sized neck is showing up as .2880
The target change is .005 which is inside the change described as being a problem in the "CatShooter" response.

With my brass thickness, I need to have my finished neck size at .2865 (.002 neck tension). I realize that this will be another step down from the .288 produced by my .290 bushing. I may need to buy two new bushings and put the .290 into my parts box. I want to check for runnout before I decide to keep using the .290 as a step bushing.

Have you tried to measure the ID of the bushing with your calipers? Not real accurate but I find if you wiggle the caliper to get it nice and tight you can get a reasonable number that is probably slightly less than the actual ID. Another check would be to take a neck that has been sized with the bushing and see if it fits inside the bushing.

Another minor issue may be the convention of the manufacturer. When you buy a .290 are they making it smaller than .290 and expecting your case will spring back to .290 after sizing. Or are they just making it .290 and you have to account for the springback. I know Forster do it the latter way.

 

[rchouser]

Ok, per RonAKA, I measured the ID of my .290 bushing. It measures .286" My brass after being run through the bushing measures .288" . That would seem to solve that mystery.

Some interesting notes. My 260 lee collet leaves a neck size of .287 which would give me a neck tension of .0015" . My RCBS standard full length 260 sizing die leaves me with a neck size of .286 which will give me a neck tension of .0025".

I have been shooting a neck tension of .0005 and haven't been able to produce a good shooting load in my new select match barrel. This is why I ended up thinking about neck tension.

Mr Salazar: My deepest thanks for your great site and the time you take to provide this kind of support to the community.

Again, thanks to all..... rc

 

[GermanS1]

RC, I'm glad to hear the site is helpful, thank you. Unfortunately, measuring a round hole with calipers will not give an accurate reading because you can't measure across the true diameter. Note that the blades are actually offset from each other (they have to be in order to slide against each other). You will always get a reading that is smaller than the actual diameter if you use calipers on a round hole.

 

[rchouser]

Ok, thanks again to German Salazar. I guess the answer is to buy a bucket of collets and just keep trying till I get the finished measurements I want.

I am going to load some neck tension .0005, .0015, and .0025 today (it is what I can produce at home with all my dies) and go to the range with my chronograph. Since my objective is to find a load that will shoot, I will do what I can do today. (I only have Saturdays to shoot).

If this was easy, I guess I wouldn't have need to ask questions.

thanks rc

 

[RonAKA]

RC, I'm glad to hear the site is helpful, thank you. Unfortunately, measuring a round hole with calipers will not give an accurate reading because you can't measure across the true diameter. Note that the blades are actually offset from each other (they have to be in order to slide against each other). You will always get a reading that is smaller than the actual diameter if you use calipers on a round hole.

Yes, the caliper will under measure the bore a bit. The sized neck is suggesting the bushing bore is .287, which is probably about right.

Strange that Redding would mark a bushing .290 and size it at .287. My experience with Forster is that the bushings are marked the same size as they really are. I understand that Forster bushings will fit the Redding die, so perhaps you may want to buy Forster bushings.

 

[robbor]

I can measure a bushing if anyone wants, I have a 332 bushing handy and a mitutoyo holetest bore gauge in the garage that measures in .0001's as i recall. I would not expect bushing size to be more than .0015 different than as marked.

 

[bglenn]

robbor
Please give us a measurement from the I D of your bushing.
I have always thought they were a little smaller so your neck would come out the size you wanted after spring back.
Glenn

 

[robbor]

Ok my 333 bushing measured .3312 plus or minus .00002 id guess on where the line line up, 2x in the center on once tward the outer edge.
Considering redding states .001 for springback that seems to be acceptable or close.
if i get a chance ill measure my 332 bushing also and check center and both ends of each.
I have other 22 size bushings but my gauge will not go small enough.

Ps if anyone has any tin bushings for sale, im interested in .248,250-256,334-341

 

[tripcrow]

You can mark, with a permanent Sharpie, the sizing measurements for all your bushings on the inside lid of the Redding bushing boxes that they can be stored in. I also mark the bushing used along with all the other loading info on a Sticky Note that goes inside each loaded box of ammo. My bushing readings vary considerably. Especially the Reddings. I've even suspected some bushings of having slipped out of the factory off center So I' be interested to see what a group of various bushings actually measure.

http://yfrog.com/nfbushings004j

Most all the brass I use a bushing on comes from a rifle where the brass's necks are turned to give .0015”- .002” clearance So the bushings are rarely sizing the brass down by much. I like the Lee Collet Die for sizing hunting brass that isn't getting full sized and for factory chambers with their large neck clearance. For whatever reason the measurements on my bushing storage box lids may vary from the actual sized measurements by a few .0001” from one box of brass to another. So I always mic the first couple bushed necks to see I'm getting what I want and check them for run-out before doing the whole box.

Edit:
Guess I oughta state that the default for Reddings is number down and for Wilsons it's number up.
The bushing size on the sticky note is always followed with an arrow pointing in the direction the numbers were when sized. I also write down the miced loaded neck size on the sticky note. Use to put it on the box. But some of the bullet lots vary in thickness so much that the box labels were way off.