Outside Neck Turn Only or Internal Ream Also

T

TScull

Guest
I will be forming a 7mm cartridge from .300 WSM brass. In the process, I will be moving the shoulder back. This process will leave the neck walls pretty thick near the shoulder and less thick at the end of the neck. It was suggested to me that I may want to reduce the neck to uniform thickness by a combination of inside neck reaming and outside turning. (I have been planning to only turn the OD.) Is there any reason that I should consider reaming as well?
 
TScull said:
I will be forming a 7mm cartridge from .300 WSM brass. In the process, I will be moving the shoulder back. This process will leave the neck walls pretty thick near the shoulder and less thick at the end of the neck. It was suggested to me that I may want to reduce the neck to uniform thickness by a combination of inside neck reaming and outside turning. (I have been planning to only turn the OD.) Is there any reason that I should consider reaming as well?
Click to expand...

If you don't ream the inside the brass will be forced to "fold" or warp to the outside which will leave a strange thin ring at the shoulder/neck junction (now in the actual neck). It's hard to get it to flatten out. I ream using a Wilson hand reamer. It's a rough cobby instrument, IMO not worthy of the craftsmen at Wilson, but it does get the job done and after a few firings the brass looks fine. It cuts hard. You'll need to find some way to drive the case if you want even a decent interior finish. I use the Lee iris-style caseholder.

hth


al
 
At what point should I ream?

I could ream after I push the shoulder back, done in small increments, once I'm down to 30 caliber or when it is down to the final 7 mm. So, do you recommend reaming at the intermediate step or wait to the final diameter?

BTW Al, I'm having a hard time visualizing the warping/folding that you described.
 
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Well, It's actually kinda' tricky.

The only way I've found is to do all of the necking down and shoulder-pushing-back done first, Get the outside shaped up. Remember to set it for crush-fit. (or slightly TOO TIGHT so that you can re-bump it for fit later) The inside of the neck now has a huge constriction which must be reamed out without ruining the rest of the neck....

Now you've got to find a reamer which fits the inside major diameter AND cuts on the end.

The K&M neckturning mandrel with the cutter on the end does NOT work IME.

The Wilson does.

So far I've been lucky, 3 times, three calibers and the Standard Size Wilson reamer (29.50) fits OK every time. I've always ordered the Standard reamers and figgered that if I needed a custom size (36 bucks) I'd size it off the standard.

What you CAN'T do is re-size the inside of the neck on a mandrel, this is why it's a little tricky.

I think that if you get it reamed to within .001 end to end THEN you can mandrel it, iron it out smooth.

My .22 and 6MM reamers cut only the constriction, only scratching the old neck They're maybe a thou undersized. My 30 cal cuts about a thou through the old neck and then reams out the constriction. I like this best, it leaves a consistent finish end to end. The reamer takes off the scale finish leaving cleanly reamed brass. Note that these fits are the result of the method used in the initial forming, the chance of achieving good fit are pretty slight.

Expect two tries :)

But it WILL work in the end.

I would size the brass and then measure the hole and order a reamer .001 larger than the hole. Measuring the hole can be tricky too.

Or you can resize the hole to the reamer using a bushing die.......

Somehow you'll get it :)



al
 
The warping fold.


OK, when you've got the OUTSIDE all smoothed up you've got the shoulder pushed back and all the extra brass is INSIDE.

If you just try to iron all of that brass back OUT without removing some then you get the ugly fold.

It helps if you visualize the brass as composed of layers, like built of thin sheets layered to thickness. Picture the resultant offset.

It actually DOES occur. I can post pictures if need be.

al
 
Well, that answers my question

Al,

That was precisely the information I was seeking. I was considering the Wilson reamer in conjunction with the K&M turner but was starting to talk myself out of it. The idea of either selecting a neck bushing to work with the standard reamer or ordering a custom diameter reamer makes the approach logical to me. Thanks for your explanation.

Tim
 
Outside turn vs. inside ream

With regards to outside neck turning vs. inside neck reaming:

Why can't you just use an expansion mandrel on your brass, which will push the dougnut and excess brass to the ouside, and then just re-turn the o.d. of your neck. Aren't both methods accomplishing the same desired effect or am I missing something?

Lou Baccino
Chino69
 
Back in the day, when the 7mmBR was a new silhouette cartridge and brass had to be made from a special small primer .308 shaped case that Remington made, the first forming dies were by RCBS. They had a ream die that was used after the shoulder was pushed back, and the neck was reduced to 7mm. With this setup there were problems with getting a tight bolt right away due to the thick brass that was left at the neck shoulder junction. Redding came out with a forming set that solved this problem by doing the reaming at .30 caliber, after the shoulder was pushed back, but before it was necked down. This resulted in the base of the reamed .30 caliber neck turning into the neck shoulder junction after necking down to 7mm, solving the tight bolt problem.

Just for the heck of it, years ago, I had a ream die made for a tight neck .222. It is set up to leave some thickness for outside turning to final thickness. In that application, since there was no shoulder location change, there was no advantage, and it took a couple of firings for the inside of the neck to be smoothed out. Reaming really roughened them up.

You may find that a custom ream die that is dimensioned correctly to ream at a larger neck diameter than your fully formed brass would do a good job for you.
 
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chino69 said:
With regards to outside neck turning vs. inside neck reaming:

Why can't you just use an expansion mandrel on your brass, which will push the dougnut and excess brass to the ouside, and then just re-turn the o.d. of your neck. Aren't both methods accomplishing the same desired effect or am I missing something?

Lou Baccino
Chino69
Click to expand...


Because of the aforementioned fold or warp.

You CAN do it your way, it just looks funny and leaves a thin ring in the neck.

al
 
chino69 said:
Why can't you just use an expansion mandrel on your brass, which will push the dougnut and excess brass to the ouside, and then just re-turn the o.d. of your neck. Aren't both methods accomplishing the same desired effect or am I missing something?
Click to expand...
This only sort of works. The neck (the "tube") is somewhat supported at the shoulder. As you run the mandrel through, usually the neck opens up a bit more at the mouth. And the spring-back is different for the portion at the mouth than at the shoulder. The difference isn't much, but can cause a slight difference is tension. Does it matter? I doubt it, but of course, no proof.

The only case I inside ream is the 8x68 necked down to .30, which in my wildcat leaves a neck over .400 long. I leave the original body/shoulder junction where it is, but push the neck/shoulder junction back to have a 40-degree shoulder.

I made in inside neck reamer out of a seating die blank with the resize reamer run in. At the top, a hardened drill bit bushing pilots the reamer, so the reamer cannot simply "follow the hole."

My attempt to get what T.J. Jackson wrote about, case necks bored true to the centerline. I'd do what Jackson did (bore them) but I can't figure out a fairly easy way to hold the case in the lathe so I'm sure I'm boring to the centerline. Blank seating dies come with a nice bored, reamed hole, so by setting up on that for cutting both the case and the drill bushing, everything should be true. By using a press, setup for each case is a snap.

After reaming, I outside turn the last .003 of the neck.

Does it work? Seems likely; I get a high percentage of loaded rounds with unmeasureable bullet runout. Does that matter? Probably not.

FWIW

Edited to clarify the neck situation. Probably still confusing.
 
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Fold or warp

alinwa said:
Because of the aforementioned fold or warp.

You CAN do it your way, it just looks funny and leaves a thin ring in the neck.

al
Click to expand...

Al,
Is this characteristic only with certain calibers or when sizing down from a larger caliber?

Here's my dilemma and the reason I'm asking. I have a 6mm BR with a .265 nd. After several firings, neck sizing only, a doughnut began to form. I'm shooting 105 VLDs. I used my expander mandrel to push doughnut to outside and turned the necks again. The doughnut is gone and I'm back in business.
In my case, would it have been preferable to inside neck ream as opposed to my method?

Lou Baccino
 
High quality cases where the virgin body or shoulder becomes part of the neck are quite difficult to make by any means. Been there and done that many times and now try to avoid it if possible. If you don't have machine tools where you can make dies, fixtures and etc. I recommend against the practice for BR quality cases.
 
chino69 said:
Al,
Is this characteristic only with certain calibers or when sizing down from a larger caliber?

Here's my dilemma and the reason I'm asking. I have a 6mm BR with a .265 nd. After several firings, neck sizing only, a doughnut began to form. I'm shooting 105 VLDs. I used my expander mandrel to push doughnut to outside and turned the necks again. The doughnut is gone and I'm back in business.
In my case, would it have been preferable to inside neck ream as opposed to my method?

Lou Baccino
Click to expand...

Lou, in your case there's no foul A'tall. It's perfectly fine to do this clear back at the shoulder.

BUT...... if you're getting donuts this leads me to believe that your initial neck turn may be incomplete. Do you have a crush-fit on your fireform brass? IF NOT, consider turning such that you stop SHORT and the case headspaces on the neckturning ring.........IF SO, then consider regrinding your cutter to eliminate the donut. Setting up properly kills ALL the birds with one swell foop! Better brass, better caselife, square caseheads and no donuts will equal BETTER AGG'S!!! :):)

(Actually, the donuts don't affect accuracy unless you touch 'em....)

hth

al
 
Doughnut

alinwa said:
Lou, in your case there's no foul A'tall. It's perfectly fine to do this clear back at the shoulder.

BUT...... if you're getting donuts this leads me to believe that your initial neck turn may be incomplete. Do you have a crush-fit on your fireform brass? IF NOT, consider turning such that you stop SHORT and the case headspaces on the neckturning ring.........IF SO, then consider regrinding your cutter to eliminate the donut. Setting up properly kills ALL the birds with one swell foop! Better brass, better caselife, square caseheads and no donuts will equal BETTER AGG'S!!! :):)

(Actually, the donuts don't affect accuracy unless you touch 'em....)

hth

al
Click to expand...

Al,
Thank you for the input. When neck re-sizing, I'm using a Wilson hand die which only sizes the first 2/3rds. of the neck. The only reason I can figure a doughnut is forming is because of this. When the time comes, after 3 or 4 firings, to bump shoulder and squeeze the base I use a Redding Small Base body die modified by Jim Carstensen to take the neck sizing bushing. Jim's die only partially neck sizes and it's my guess this is the reason, as with the Wilson die, for doughnut formation.

When I recently removed the doughnut using the expander mandrel, I set my neck turner up so that I was skimming by the first 2/3rds. of the previously turned neck and taking brass off the remaining area right to, and a sqootch beyond, the neck shoulder junction. Is this what you are referring to in your above quote?

"IF NOT, consider turning such that you stop SHORT and the case headspaces on the neckturning ring".

When I originally performed my neck turning with virgin Lapua brass, I went a tad beyond the neck/shoulder junction. The brass did have a slight crush fit.

Any and all info./comments/critiques/additions/enhancements greatly appreciated.

Lou Baccino
 
"Is this what you are referring to in your above quote?"

yes


BTW is you cut your sqootch deeper you'll completely eliminate the donut. Look at the closeup pic in this post to see how the cut works and to see that the donut is actually shoulder brass. Also note that in the pix in this post the shoulder cut IS NOT ideal, but hopefully you can see how it can be fixed.

http://www.benchrest.com/forums/showthread.php?t=57651&highlight=alinwa+neckturning

al
 
Skootch cut

alinwa said:
"Is this what you are referring to in your above quote?"

yes


BTW is you cut your sqootch deeper you'll completely eliminate the donut. Look at the closeup pic in this post to see how the cut works and to see that the donut is actually shoulder brass. Also note that in the pix in this post the shoulder cut IS NOT ideal, but hopefully you can see how it can be fixed.

http://www.benchrest.com/forums/showthread.php?t=57651&highlight=alinwa+neckturning

al
Click to expand...

Thanks al.
All is right with the world.

Lou Baccino
 
alinwa

Al,
Has anyone ever told you that your style of posting is reminiscent of E.E. Cummings, the witty poignant poet?

Lou Baccino
 
my solution

When I made cases for my 30-338 Lapua and shortened the case, I used my final neck sizing bushing that was larger than the case body diameter to chuck the case in a Lathe. Then we took a micro boring bar and inside neck reamed the cases. With a pin guage in the case mouth we got less than .0005 inches of runout. If you have the access to a lathe then this is the way to go.
 
E.E. Cummings

alinwa said:
why no louis but i'll take it as a compliment

:)

al
Click to expand...

It was meant as a compliment. Take a look at some of E.E. Cummings work sometime and you'll see similarities in the two styles of expression.

Lou Baccino
 
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