taper reamer inside necks, cb accuracy

  • 389 Views
  • Last Post 20 May 2018
Ken Campbell Iowa posted this 16 May 2018

while prepping a cigar box of mixed, mongrel  30-06 brass for groundhog targets, it came upon me that if just ID taper reamed the necks it would save me from deburring, flaring neck mouths  and probably excess working of necks from the belling/sizing at each reloading ....

also i remembered that in the few ( 3 or 4, in 22 and 7 mm  ) instances i had tried it years ago while developing serious loads, it seem to give better groups over straight neck loads  ...

maybe it allows the bullet to pivot from deeper in the neck ... thus more self-alignment ?? ....  kinda like our bench gurus who seat just by the gas check ....  and maybe it allows the soft bullet to expand inside the neck before it moves forward and thus gives a better fit in the throat (  since many throats are bigger than a bullet that you can seat into a factory spec neck ) ...

i remember JohnA mentioned this a while back, so maybe next loading i will taper ream the whole box ....  not like it is 284 winny brass, i guess.   any comments welcome.

ken

Attached Files

Order By: Standard | Newest | Votes
Tom Acheson posted this 16 May 2018

Ken,

Interesting hypothesis.

What kind of an angle is the "taper" and about how "deep" down inside the neck does this micro-machining take place? Is this a tool that is used in a case length trimmer? Who sells the tool?

Thanks!

Tom

Attached Files

Ken Campbell Iowa posted this 16 May 2018

tom .... probably standard industrial taper pin reamers would be close ... these are just over 1 degree ( corrected:  included angle ) .... so in 1/8 inch would be about 0.002-0.003 taper diameter change ....    in our range these would be about 6 inches long, so might be able to be crutched up for use on a "" wilson "" or other commercial neck trimmer/reamer .   i can't remember how i did it before but likely a 5c collet  closer body under a bridgeport .  the cut is very light, i imagine hand reaming would be easy enough ... maybe a depth stop button on the reamer .

here is a decent source for tapered reamers... and other cutters.

  https://drillsandcutters.com/straight-flute-taper-pin-reamers/

ken  

Attached Files

John Alexander posted this 16 May 2018

I believe Ken is right. taper reaming the inside of the case neck is a good idea. I have no proof but I also believe it may also allow the bullet to pivot a bit and better self align in the throat.

He is also right that I wrote about this in TFS (#218 July. Aug. 2012). I never flare cases and don't own an M die because I believe this is a better method.  Maybe because I don't like useless work and using the taper reamer is only done once instead of for every reload as with the M die. I use what is called a Repairman's taper reamer with an included angle of about 9 degrees. (about $5 from Grizzly). I do the reaming by hand, Lyman's "VLD" reamer with included angle of 30 degrees would probably work about as well.

Neck reaming one time, combined with the Lee collet die eliminates -- lubing and cleaning cases, expanding and flaring with the M die, each time the case is loaded.  It also reduces work hardening of the case to almost zero which eliminates the need to anneal case necks -- EVER.   This saves me a LOT of labor and I believe I get a little better accuracy. See my article for more details.

I once used one lot of twenty cases for most of my experimental work for a couple of years and used the method above for reloading. The cases were never annealed.  The first neck crack happened on the 184th reload and the second one on the 218th reload at which time I retired the remaining 18. with that kind of case life it is not worth my time to anneal although you might get a few hundred more reloads out of the cases if you like to anneal things.

I don't know why everybody isn't using this method for any caliber that Lee makes a collet die for.

John

Attached Files

45 2.1 posted this 16 May 2018

Interesting John, but if you have read Harvey Donaldson, he related case life in a schuetzen rifle as being about 2,800 shots with the case being worn out because it wouldn't hold the primer in. You could try the fitted case approach by inside neck reaming a fitted case to hold the bullet to your prescribed seating depth. No sizing at all, just de and reprime, charge and hand seat. This can be done with the Lee Loaders quite easily. Using those can produce some very small groups if done correctly.

Attached Files

R. Dupraz posted this 17 May 2018

This is an interesting topic Gents !

Some time ago, I quit using my RCBS chamfering tool that I bought back when I started reloading. It is now on the shelf gathering dust, never to be used again on the inside of case mouths. Instead, I use a Sears hand taper reamer that I got years ago for some unnamed project. And use it exclusively as a matter of routine on new case mouths. Mine has an eleven degree taper.

You are right John in that it only has to be used once and I can't say for certain that it enhances accuracy either but I can say that it certainly doesn't hurt. What it does do is make seating cast bullets much easier and smoother. Also. it noticeably  improves the concentricity of the loaded round when seating cast which does enhance accuracy. especially long nose bore riders. That I can prove.

And, it is especially helpful when used on the mouths of thin fragile brass, such the .218B for example. 

I concur John.

R. 

.  

Attached Files

OU812 posted this 17 May 2018

After reading John's post I will never anneal again. Neck tension will stay more consistent I believe.

I just purchased another 100 Lapua 223 cases and will just leave these as is (no neck turning or annealing) and neck size only with Lee collet die. I will chamfer case mouths only with Lyman low drag reamer (no M die or any case flaring tool needed).

 

Attached Files

BudHyett posted this 17 May 2018

Neck reaming has one potential problem; reamers tend to follow the existing hole. If the walls are uneven, they will possibly still be uneven. The reamer will trim off an even amount of the inside and leave the variance in wall thickness.

The only way to have even thickness walls is outside neck turning. 

My experience with Lapua brass is the neck-turning to a wall thickness of .015 is frustrating, they are already uniform. 

Country boy from Illinois, living in the Magical Pacific Northwest

Attached Files

45 2.1 posted this 17 May 2018

Neck reaming has one potential problem; reamers tend to follow the existing hole. If the walls are uneven, they will possibly still be uneven. The reamer will trim off an even amount of the inside and leave the variance in wall thickness.

The only way to have even thickness walls is outside neck turning. 



They do make dies with a fitted reamer to produce even wall thicknesses via inside neck reaming... expensive, but you can specify what wall thickness you want. The need to ream is to produce even neck thickness AND to produce case necks that actually fit the chamber with very little slop when loaded.

Attached Files

Ken Campbell Iowa posted this 17 May 2018

hi 45 2.1 ... i am having trouble visualizing how an inside neck reamer can create even neck thickness on a brass where the neck is uneven from the factory .    is there a discussion on this somewhere ?  or a mfg. advertisement ?   or is this reaming fixture used AFTER the brass neck is prior od turned on a guide spud ??

thanks, ken

 

 

Attached Files

45 2.1 posted this 17 May 2018

hi 45 2.1 ... i am having trouble visualizing how an inside neck reamer can create even neck thickness on a brass where the neck is uneven from the factory .    is there a discussion on this somewhere ?  or a mfg. advertisement ?   or is this reaming fixture used AFTER the brass neck is prior od turned on a guide spud ??

thanks, ken

Wrong on all assumptions Ken. RCBS used to make these.... it's basically a open top sizing die with the top hole in line with the case/neck, a fitted reamer slides in the hole and reams the case neck on the inside.....Very Close Tolerance. I used one like it to make a few fitted cases for a Sharps 40-50 BN. I also got a Simmons Pope style Re-De to decap and reprime with it. Basically you fire the case, decap, reprime, charge and hand seat the bullet in the case neck to an internal shoulder. It's more precise doing it that way, but could also be done by outside neck turning to where the base of the bullet would be, then fireforming so the shoulder for the bullet would be on the inside. I have fired most of that brass over 250 times and all of the brass looks like it was on the first firing.

 

Attached Files

John Alexander posted this 17 May 2018

Bud,

I didn't explain well enough.  What I was describing in my post and in the FS article as well has nothing to do with reaming the neck for uniform thickness.  The taper reamer is used to make the inside end of the neck only slightly larger than the diameter of the bullet base to let the bullet get started smoothly and without shaving lead -- same as the purpose for flaring.

This tapering requires no particular precision and can be done by hand because when seated the bullet doesn't tough the tapered part  of the neck.

John

Attached Files

John Alexander posted this 17 May 2018

45 2.1,

Thanks for bringing up other options. Of course breech seating doesn't involve sizing the case and the cases should last forever.  The same should be true for custom match rifles for loaded cartridges with a tight necked chamber. These setups require only a few thousandths of sizing - OR NONE if set up tight enough that elastic spring back of the case neck will still grip the next bullet.  Of course the jacketed bullet crowd with this type of chamber push the limits of pressure and life is probably limited by cartridge head expansion of primer pockets. Some of our heavy and UNR and UMP shooters may use similar pressures for their 30BRs and such.  However, with a tight necked chamber and pressures kept to usual CB pressures their cases should last almost forever -- just like breech seating. However I have never asked them. 

What about it all you custom chamber shooters how long does your brass last if you keep the pressures low???????

That said, my interest is in cast bullet performance in factory rifles and am stuck with factory chambers and their required tolerances.  These usually let the case neck expand in the neighborhood of 0.008" from the neck diameter of the loaded cartridge and there isn't much you can do about. (Short of specially manufactured thick neck cases (maybe 22-250 cases made from 30-06 cases to get a thicker neck.)  So sizing is necessary to grip the bullet but using either a collet die or a bushing type neck sizer can make cases last a very long time without annealing at the usual CB pressures.

John

 

Attached Files

frnkeore posted this 17 May 2018

This is what a RCBS, inside neck reamer looks like.

The reamer shank has about .0003 - .0005 clearance in the reamer body and the case neck is contact with the die.

Frank

 

Attached Files

Ken Campbell Iowa posted this 17 May 2018

thanks guys for the enlightenment on the inside reaming die. 

i am now brought along to the point that since the od of the neck in the sizer is round, if the neck wall varies, then the inside hole has to be off-center ..... so the reamer has to cut a diameter at least big enough to take a teensy cut on the thinnest neck wall, or you wind up with that egg-shaped hole i was worried about.

so whether you neck turn or inside ream it appears that a lot of pre-planning is required;  co-ordinating chamber neck dimensions, new sizing die/bushing/collet spindle .... and bullet diameter.      but then i just loaded a couple hundred rounds in old conventional dies ... still hearing that squeak from the expander buttons ...   

thanks again ....  ken

Attached Files

BudHyett posted this 18 May 2018

John - Now I understand the thread beter. I am a strong advocate of outside neck turning as I use bushing neck sizing dies. This is from the jacketed bullet days where I reduced the expander button by .001 / .002 to smooth it and to give tighter grip for more uniform ignition. 

The thought of inside taper reaming to ease the bullet entry while seating is deburring in essence. With new brass, we deburr the outside and inside of the neck as a matter of course. Initially using the standard tool, the deburring worked. This tool was replaced for the inside neck by a long taper chamfer tool to deburr plus remove a slight amount of metal for an inside taper. 

Alice and I are experimenting with tighter neck tension now for her Savage. The lighter velocity loads show greater vertical dispersion at 200 yards. The variables are; 1) neck thickness, 2) case neck tension, 3) how many shots since last anneal.  

On a side note, I remember meeting Fred Huntington stopping at Freeland's in Rock Island, Illinois many years ago. Fred stopped  on his return flight from the NRA Annual Meeting and was caught the next day by the airport being totally fogged in. Al Freeland called several serious shooters to meet him including my uncle Verne. (Verne called me and told me to report at his house,)

I sat like a mouse in the corner and listened, I was just then starting reloading. The discussion was case neck tension and accuracy. The subject was between neck-reaming and outside neck turning. This discussion soon turned into a serious debate. There were strong opinions. 

Country boy from Illinois, living in the Magical Pacific Northwest

Attached Files

45 2.1 posted this 18 May 2018

There are other options also. Whether they work or not depends entirely on the methodology used and choices a person makes........... even with loose tolerance necks and chambers. Oversize bullets, alloy choice, load pressure along with stop ring bullets are all topics that could be discussed here.

Attached Files

John Alexander posted this 18 May 2018

45 2.1,

You are of course right, there are always several ways to skin a cat and interesting discussions are what make the forum worthwhile and fun. I, and I am sure others, would appreciate further discussion on the topics you hint at.  As time allows, please start one of more threads on these topics and how they could contribute to our cast bullet knowledge.  You could start by giving us your experience with the technique which I'm sure would be educational and well attracting lively contributions from others.

Thanks in advance.

John

Attached Files

OU812 posted this 18 May 2018

Such as taking a fat Lyman 314299 bullet and swaging it down to fit your new factory 308 rifle. Swaging down the whole bullet (bands and bore ride section) in one easy step.

Attached Files

beltfed posted this 18 May 2018

To clear this up:

Ken C:

Are you initially in this thread really talking about "long, gradual taper inside neck

Chamfering"?  In order to allow gentle seating of bullets?

beltfed/arnie

Attached Files

Tom Acheson posted this 18 May 2018

Resurrecting the annealing thing. Two thoughts.

I shot a round known as the 30 PPC for several match seasons. After a Regional match the fired cases went into a vibratory case cleaner. In the process of poking media out of the flash hole, here was a case with no neck! Examining the media I could not find it. Oh oh…there it was in the throat of the gun. My good friend John Kaufenberg and I tried quite a few stunts to extract that piece of neck material but no luck. So that had to be the very last round shot at the match…talk about strange. It could have been the first round and I would have been out of luck at the match. Those Lapua cases had been fired 24.75 times each until that first failure. They were never annealed. Had they been annealed I might still be shooting that round today. Off comes the barrel and new one was installed.

The black powder cartridge crowd is quite focused on annealing. Not just for case life but to support the theory that the case mouth needs to be flexible enough to expand upon ignition to develop a good gas seal in the chamber as the bullet heads down range. An annealed neck is soft enough to allow the neck to “flex” to meet that need. So maybe the black powder parameters are different than smokeless? Who knows. But you’ll not convince very many of them to quit annealing. Some of them are so committed to annealing that they anneal all cases after each firing.

FWIW

Tom

Attached Files

Show More Posts
Close