to ream or turn?

[funnyjim014]

I'm just starting my first case conversion. 06 and 270 to 7mm mauser. I got the resizing down.I have trim die but have to cut and trim yet. I assume I will have to adjust neck thickness. Should I turn the outside or ream the insides.what are the pros and cons of each. I have never had to do either before

[357Mag]

Funnyjim -

Howdy !

Truth be known... you may need to do both.

It is possible that after an inside neck ream ( to remove doughnuts ), you might also have to outside neck turn the brass.

Outside neck turning is used to uniform neck wall thickness about the central axis of the case.

You'll need to mic the case necks prior to doing either brass removal step, to make sure you don't cut them too thin... as a result of either process; above.


With regards,
357Mag

[Char-Gar]

Turn the necks...

[funnyjim014]

Ok I'll order some from Midway and measure them up

[country gent]

A light neck ream will smooth and thin necks quickly and accurately. Followed by a neck turn you get very consistant thickness in the necks. Neck turning by hand can be a chore if to much is there to be removed. I would recomend checking neck thickness with a ball mike or gage made for the purpose. ( Brass dosnt always flow evenly). If more than .0005 -.001 run out. Neck ream leaving .001 -.002 to be removed from the outside after. When measuring thickness check cases evey 90* and close to shoulder and close to mouth. Cases thicken towards the head and if you have what was case shoulder in the new neck it may be thicker towards the back. This is also a good time for a chamber cast of your rifle, for neck dia. If your going to do this the neck dia of your chamber - .0015 will give a "fitted" case neck set up. eam and turn necks so loaded round is .001 below neck diameter. This can make for very accurate ammo in a good rifle. I have a NRA match rifle chambered to .243 with .268 neck I turn case necks for a loaded round of .267 rounds chamber easily have enough clearence to release bullet but are centered better. Brass last longer due to less stretch and needed sizing.

[Ballistics in Scotland]

Best of the lot is a forming die which includes its own reamer. That will cut in perfect alignment, whether it is just the "dreaded doughnut" or the full length of the neck, and I would call it better than any of the reloading firms' neck turning devices, although I think it should be possible to make a device to do as well by turning on an engineering lathe.

What I think is most suspect is using a reamer in a bench drill or lathe when the case is held simply by its base. It isn't unusual for fired cases to have the base very slightly inclined, or even a thousandth of an inch of dirt can move the neck off-center by four or five.

[MarkP]

I prefer to use spiral fluted reamers when available as compared to straight fluted reamers. You can order chucking reamers in 0.0005" increments, HSS or carbide if you have several you need to ream.

When forming your cases, take your expander ball out of your die. The cartridge wall will be tapered in the area of the new neck.

[Geezer in NH]

I vote turn

[Don Fischer]

I'm not sure why you would need to turn or ream. I've taken 30-06 case's to 280, 6.5x06 and 308 case's to 243 without needing to turn

[EDG]

Neither one will be needed. Infantry cartridge chambers are so large that you do not have to turn.

To verify just measure the neck of your chamber.

[funnyjim014]

[QUOTE=EDG;3536668]Neither one will be needed. Infantry cartridge chamber are so large that you do not have to turn.
Well i made a test round up with no turning or reaming...it chambers with just a bit of extra force on the bolt.i did notice a slight buldge at base of sholder ,most likly a little over zellus on the crimp. Made 5 test rounds of 36.5 imr 4064. Try em out tomarrow

[EDG]

I have formed both .270 and .30-06 to 7X57 without turning and 30-06 GI match brass to .25-06 without turning.

[popper]

even a thousandth of an inch of dirt can move the neck off-center by four or five.

Good point for neck turners.

[Ballistics in Scotland]

I prefer to use spiral fluted reamers when available as compared to straight fluted reamers. You can order chucking reamers in 0.0005" increments, HSS or carbide if you have several you need to ream.

When forming your cases, take your expander ball out of your die. The cartridge wall will be tapered in the area of the new neck.

A dedicated form die might or mightn't be sized to produce a case neck which needs to be sized down further in the loading die. But I think you are talking about forming in the loading die. This may be fine, but minus expander button it reduce the interior diameter smaller than bullet diameter, some brands of die by only a little but others by quite a lot. If you ream the unexpanded neck, it could leave you with more clearance than you need between cartridge neck and your chamber. Even military rifles don't all have large chambers, and plenty of sporting 7x57 rifles were as closely chambered as any other.

I'd make a cast and measure that chamber neck, which itself may have a slight taper, and be otherwise measurable only by an expensive set of pin gauges. Sacrificing an expander button is better business than sing brass you don't like, for as long as you have the rifle. You could reduce a standard 7mm. expander button with abrasive paper while holding it in an electric drill, until it gives outside of the case just the clearance in your own chamber neck that you would want. Then decide whether it needs reaming, and to what size. For loading you would use the unmodified expander button.

A hand reamer is cheaper than the fine graduations of machine reamer, and it has a tapered lead which helps to centre the case if a bench drill is used. But they don't come in that fine range of sizes, and having someone make or modify a reamer is likely to be most expensive of all. 9/32in. is a standard hand reamer size though, and equals .2812in. If you think that is a thousandth or two smaller than you would want to load bullets into, just size your temporary case-forming button to give that extra thousandth or two clearance in the chamber and again use the unmodified button for loading.
me.
I've never found anything wrong with straight-fluted solid reamers when turned fast by machine, but they might if used by hand, for which reason almost all hand reamers are spiral. I mistrust adjustable reamers for just about any job. They are extremely likely to cut a slightly star-shaped hole. There is no point at all in paying for carbide to use on clean brass, but I suppose you might want to use it on something else another time.

I think slight tightness of neck in chamber is more dangerous than many people think. They measure bullet pull or they assume it can't be very different from bullet push, in the bullet seating operation, but I don't think that is the issue. Col. Townsend Whelen was involved in the experimental issue of National Match .30-06 ammunition with tin-plated bullets, and this increased the bullet pull so much that they broke the testing machine. But accidents didn't start happening until people who didn't know that tin was pretty good at cutting nickel fouling on its own used the forbidden illicit dodge of greasing the bullet. Then they did. He thought the problem arose when grease filled the space between neck and chamber, for like water grease acts like a solid if pressure on it is sufficiently sudden. Nearly all diving height records have involved serious injury.

My interpretation is that bullets aren't released from the case by pulling, or rather pushing. It happens because pressure comes between case-neck and bullet, like blowing into a clinging rubber glove, and even a lightly-clamped neck prevents that.

[Don Fischer]

A dedicated form die might or mightn't be sized to produce a case neck which needs to be sized down further in the loading die. But I think you are talking about forming in the loading die. This may be fine, but minus expander button it reduce the interior diameter smaller than bullet diameter, some brands of die by only a little but others by quite a lot. If you ream the unexpanded neck, it could leave you with more clearance than you need between cartridge neck and your chamber. Even military rifles don't all have large chambers, and plenty of sporting 7x57 rifles were as closely chambered as any other.

I'd make a cast and measure that chamber neck, which itself may have a slight taper, and be otherwise measurable only by an expensive set of pin gauges. Sacrificing an expander button is better business than sing brass you don't like, for as long as you have the rifle. You could reduce a standard 7mm. expander button with abrasive paper while holding it in an electric drill, until it gives outside of the case just the clearance in your own chamber neck that you would want. Then decide whether it needs reaming, and to what size. For loading you would use the unmodified expander button.

A hand reamer is cheaper than the fine graduations of machine reamer, and it has a tapered lead which helps to centre the case if a bench drill is used. But they don't come in that fine range of sizes, and having someone make or modify a reamer is likely to be most expensive of all. 9/32in. is a standard hand reamer size though, and equals .2812in. If you think that is a thousandth or two smaller than you would want to load bullets into, just size your temporary case-forming button to give that extra thousandth or two clearance in the chamber and again use the unmodified button for loading.
me.
I've never found anything wrong with straight-fluted solid reamers when turned fast by machine, but they might if used by hand, for which reason almost all hand reamers are spiral. I mistrust adjustable reamers for just about any job. They are extremely likely to cut a slightly star-shaped hole. There is no point at all in paying for carbide to use on clean brass, but I suppose you might want to use it on something else another time.

I think slight tightness of neck in chamber is more dangerous than many people think. They measure bullet pull or they assume it can't be very different from bullet push, in the bullet seating operation, but I don't think that is the issue. Col. Townsend Whelen was involved in the experimental issue of National Match .30-06 ammunition with tin-plated bullets, and this increased the bullet pull so much that they broke the testing machine. But accidents didn't start happening until people who didn't know that tin was pretty good at cutting nickel fouling on its own used the forbidden illicit dodge of greasing the bullet. Then they did. He thought the problem arose when grease filled the space between neck and chamber, for like water grease acts like a solid if pressure on it is sufficiently sudden. Nearly all diving height records have involved serious injury.

My interpretation is that bullets aren't released from the case by pulling, or rather pushing. It happens because pressure comes between case-neck and bullet, like blowing into a clinging rubber glove, and even a lightly-clamped neck prevents that.

A to tight neck will hold and not release the bullet properly but worse, it will raise pressure drastically. If the case's are being used without turning, watch for pressure, it should not be normal unless you've exceeded max in your rifle.

[fixit]

in everything, turn, turn, turn. there is a...oh, flashback time!

[GONRA]

Ballistics in Scotland sez: "Col. Townsend Whelen was involved in the experimental issue of National Match .30-06 ammunition with tin-plated bullets, and this increased the bullet pull so much that they broke the testing machine."

GONRA believes the tin plate resulted (over time!) in mutual diffusion with the cartridge case material,
in effect making the bullet / case neck a solid metal structure - hence the enormous overpresssure.
No more tin plated bullets for brass cartridge cases!
You experts out there know the history on this stuff and can checkitout....

[Crusty Deary Ol'Coot]

I also vote for outside turning, and there is no need to do both.

Now, as Don Fischer indicates, when decreasing neck size to the 7mm, it is possible that and of course this depends on the chamber in question, not turning the case neck and thereby the neck thickness could lead to VERY dangerous and even gun destroying pressures.

I also have formed brass, .308 to a smaller neck size - .243 - and have been lucky enough to not have a problem. NO MORE, it only took one reading of an article about a nice pre 64 - .243 Winchester being reduced to scrap by this conversion to make a believer out of me.

30 cal to .270, I'd not worry a lot about it, but below that, better to be safe then sorry.

Crusty Deary Ol'Coot

[EDG]

The whole point is to know what is needed for the rifle.
There is no reason to do anything unless you know it is needed.
If you turn or ream necks unnecessarily you just make the necks sloppy and the rifle may not shoot as well.

In my own experience I have had 2 instances where the case needed turning.

I formed .303 British brass out of .444 Marlin and it worked ok, but when I used Hornady .405 Win brass for .303 it had to be turned.

When I used a .380 bullet in my .380 groove dia 38-55 rounds loaded with cast bullets in WW brass would not chamber.
I found that Starline brass was about .0015 thinner so I used it for rounds that would chamber.

Learn to measure the chamber neck diameters. If you cannot measure chambers and ammo, you probably should not be forming brass because you are flying blind.

[funnyjim014]

Went to range to test fire.... turns out my new-TO-me chilian mauser has a broken firing pin.... .