neck bushing ID

[savet06]

I did a search and was unable to find this covered previously.
I have several neck bushings from the same manufacturer, two of which are of the titanium variety. The .324,titanium) ended up sizing the necks to .322. I checked the ID of the bushing and with my mitutoyo digital caliper it measured .322. I realized that this may not be the best way to measure this small of an area, but the proof I have on the newly sized necks tells me that it is on the money.
I checked the other 3 bushings I have and they were all .001 undersized.
Has this been consistent with what others have found?
Just wondering if it's worth contacting the manufacturer. I would have thought it a fluke if only one of the four was off, but all four just seemed a little much.

thanks,
Mike

 

[expiper]

If they are Redding ..that is "typical" compared to the ones that I have...they are usually smaller than stamped ...some as much as .005" ....they work good and wear good ..but you gotta size a cupla ctgs. with em and then measure and see what u got ...the Wilson brand bushing are much more predictable and can be inverted to change size by .ooo5 ....and with the cost at 10$$ a pop...I dont want a cigar box full of the wrong size!!...the Wilson brand bushings are a lil softer...but I wuld rather have them wear out,,I usually get 3000+ loads before wear is a problem)),,than have em rub,,wear)) .00001 off the case neck evry time you run it in ...Roger

 

[rayjay]

To measure the ID of an item you need a measuring device with round cross section contact points, not flat contact points like a caliper.

 

[GermanS1]

Measuring a small hole with calipers is simply not accurate, forget the reading you got. The caliper does not,cannot) measure across the diameter of the piece because the jaws are not on the same plane.

More importantly, the bushing is likely correctly marked, but that doesn't mean it will yield a neck diameter of the nominal size. If you size more than 0.003" with a bushing, it begins to taper the neck and results in a smaller than nominal size. Most chambers,other than true BR chambers) will require more than 0.003" to get the neck down to where you want it; the correct approach is to use two bushings and do the sizing in steps.

As an example, my 6BR chambers have a 0.271" neck, fired cases come out at 0.270"; I need to size my necks,lightly turned) with a 0.268" bushing, then a 0.265" bushing. It takes about 5 minutes to run 70 cases through a second time since they are already lubed and in the tray. The result is correctly sized necks with no taper and great concentricity.

 

[CatShooter]

As said above, you cannot use a caliper to measure the ID of a bushing.

As to the smaller size, it is discussed on the Redding website, and on this site - ad nauseum.

Go here for the Redding page:
http://www.reddingreloading.com/techlinepages/bushingselection.htm

Go here for some threads on Bushings:

http://www.websitetoolbox.com/tool/post/6mmbr/vpost?id=2586812&highlight=redding+bushing

http://www.websitetoolbox.com/tool/post/6mmbr/vpost?id=2729205&highlight=redding+bushing

.

 

[savet06]

Thank you all for the replies. I noticed that when I used the .324 that my otherwise very concentric rounds were as much as .003-.004 in TIR. I will now go in step-wise fashion and see how it goes.
Just when I thought I was getting this stuff down pretty well. The more I learn the less I know....

Thanks,
Mike

 

[284driver]

I assume you are using a neck die with the bushing as i am. I had the runout problem which is driving me insane. Would a full length bushing die alleviate this runout problem without stepping down in bushing sizes twice? seems to me the full length bushing die would keep the case in tighter tolerances so as not to allow the neck to go all over the place.

 

[savet06]

Actually I am using a FL sizing die set to bump the shoulders after each firing. I read the links posted by catshooter, and learned a heck of a lot. I had purchased a wilson neck sizing die for the 30br, but after each firing the cases need to be bumped so the neck sizer sits unused for now.

I am also trying my hand at annealing, and after all the reading out there I am still not getting consistent results. I am, however, thoroughly enjoying the mistakes and successes as I go.
Mike

 

[284driver]

I called Redding about this, and someone, maybe CatShooter told me if you size down the neck more than .005 that the runout goes off the deep end. There is an article about this on redding's website in the tech tips...I sent 10 fired cases and my die to Redding and the tech guy is going to hopefully come up with something that will work to keep the runout down. I was getting .007 to .008 runout with the type s neck bushing die.
Kinda got off subject,sorry.
Good Luck