Neck Reaming Die Question - Finding Reamers

[Rfeustel]

I’ve never used a neck reaming die. I see a number on eBay for various cartridges. Many lack the reamer itself.

I set upon searching McMaster for reamers to see if one can get a reamer after the fact. I did see hand reamers with straight flutes, but it wasn’t clear to me (a) they would have the shaft diameter of given reaming dies, or (b) whether I could ever find the right reaming diameter without getting lucky.

Were the reamers supplied with such dies (e.g., from RCBS) specialty reamers, or is there some source of reamers by the thousandth somewhere?


Thanks

[Rcmaveric]

Case mouth reaming is a bit different than say reaming a chamber. You have to buy the contraption then get the mandrels or reamers for it.

There are two kinds of reamers. Inside case neck and outside. Vsrious debates on them and pros and cons.

An inside case neck reamer like the Fostner ones, you would need a fostner reamer for that caliber. I recommend seeing if they have a user manual you can download so you can see how to do it and see what you need. As i am not familiar with them. I think you need to buy the reamer for the dimensions you need. There is math involved and measuring.

Then the outside case neck reamers are easier. I use this one and use the RCBS hand reamer. You just buy the mandrels for the calibers you reload. Its pretty universal. You install the mandrel for your caliber. The cutter is the handle and you set it up per instructions in the manual. Its pretty straight forward. Then plop a resized case on the mandrel and spin it either by hand or drill down the mandrel. It shaves off material.

Either way you go its all about uniforming case neck tension. and hopefully increase case concentrity. Which will equal more accurate ammo.

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[AntiqueSledMan]

Hello Rfeustel,

I used the RCBS Neck Turning tool when I formed 7.65x53 from 30-06 Military brass.
It has an arbor to support the neck while cutting off the outer side of the neck.
I would imagine the neck turning die is required to keep the neck from expanding while reaming.

AntiqueSledMan.

[country gent]

What are you wanting to accomplish thinning the necks? Is this a reformed case the neck has thickened on from sizing down or the shoulder has became part of the neck? A fitted chamber with tight neck?

Neck reaming is an easy way to thin the necks on cases that have thickened from reforming. There are set ups that fit in a case trimmer better is the die body set up for this. The latter provides more support. Reamers tend to follow the existing hole so truing up neck wall run out isnt their strong suit. On the plus side set u s easy and quicker. the p;us to the die body type is the case is supported on the outside the reamer is supported in its bushing the case cant expand around the reamer as it dulls.

Neck turning is removing metal from the outside of the neck usually with a mandrel and single point cutter. Dine right it will be very accurate and remove neck wall run out to .0001. the cases is normally sized on the mandrel and then the cutter set to the desired wall thickness ( this requires some trial and error) the cases then turned to thickness. This works very well for fitted chambers where the neck dia is undersized and the case is fitted. Care must be taken to get all the way to the shoulder so as not to leave a ring or doughnut at the base of the neck.

To determine what you need as to reamer measure a sized case ( I prefer no expander ball used) outside neck dia. then subtract wall thickness X 2 this is the inside dia of the sized neck it will be under bullet dia now subtract the desired neck tension you want and this is the biggest reamer you can use go .001 smaller for the expander and thats the reamer dia you need

[Rfeustel]

Thanks, all. Yes, I’m internal neck reaming owing to reforming cases (bottlenecking down). I saw a nambu die for this purpose, but it lacked the actual internal neck reamer with the die. So I set out trying to figure out if getting a proper reamer for the die is possible. It’s not clear to me that I could actually find reamers that would fit properly. I’m wondering if that’s an exercise in futility or if there’s a source of reamers somewhere that could work.

[country gent]

Reamers are available in .001 increments hand and machine from most tool supply shops. Mc Master Carr Grainger MSC should all list them. T&A Tool in Toledo Ohio lists them in their catalog and will sell online / mail order. Basically you want a straight flute hand reamer and and if you dont have one a smaller tap handle to turn it.
A search for T&S tool supply Toledo Ohio should bring up their web site

To simply ream a thick neck .001-.002 subtracted from bullet dia should get you in the ball park

A little dish soap or water soluble cutting oil on the reamer when cutting will ease the cut and improve finish.

[BP Dave]

You might be able to buy a replacement reamer from the manufacturer.

In the alternative it kind of depends on how the die is set up. From my limited experience with commercial-made neck reamers, the hole through the neck of the die was straight through and was the diameter of the outside of the neck. The shank of the reamer was a slip fit into that hole. Because the brass is about 10/1000ths thick, the cutting portion of the reamer was about 20/1000ths smaller than the hole. The odds of finding a ready-made reamer with the dimensions you will need (other than one made as a neck reamer for your caliber) is pretty small. It might be possible to make a sleeve to center the reamer in the hole, perhaps out of brass or steel tubing, or else some kind of guide that slips over the top of the die and centers the reamer. Making a guide would take lathe work. You might be able to use cut-off case necks for brass bushings. Or you might be able to carefully freehand cut it--you would probably lose some cases, and the work might not be very precise, but I don't think you're shooting precision matches with your Nambu. You would also need to be careful not to run the reamer against the die, as doing so would not be good for either one of them.

Of course, if the die is set up so the hole through the top is the desired neck diameter (I think this is unlikely), you should be able to find a straight reamer that is a slip fit and just use it. Odd size reamers show up pretty often on the 'bay. It can help to search in four decimal places rather than three, and be willing to fudge a .0001 or so; think .3209 vs. .321.

Good luck!

--DJ

[Rfeustel]

Ah, thanks guys. I get it now.
Much appreciated.

[tctender]

Another thought is the reamer is used after firing. The case turner is used after sizing. I found this out after i changed brass brand necking down for my 375 JDJ . The Starline brass is thicker than the Remington brass and caused a tight neck with the loaded round being hard or impossible to chamber. I had to go with the neck turner as i was unable to fire the brass first. The necks were too thick. Dont know if you are able to fire yours before reaming but just a thought. This is with the Forster type.

[stubshaft]

All of the neck reaming dies in case forming sets I have used have always been used BEFORE firing. The RCBS forming dies that I use are for converting 308 to 7mmBR and forming 250-3000 from 30-06 brass. They have dedicated dies for the reaming operation. I cannot imagine trying to load a 7mm bullet in a case formed from a 308 BEFORE reaming it and having it fit the chamber. That being said I much prefer outside neck turning as it has less runout and is more concentric.

[Rcmaveric]

I make 260 Rem brass from 308. I also make 6.5 Grendel Brass from 7.62×39.

I resize.
Outside Neck turn.
Then fire form.

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[M-Tecs]

I’ve never used a neck reaming die. I see a number on eBay for various cartridges. Many lack the reamer itself.

I set upon searching McMaster for reamers to see if one can get a reamer after the fact. I did see hand reamers with straight flutes, but it wasn’t clear to me (a) they would have the shaft diameter of given reaming dies, or (b) whether I could ever find the right reaming diameter without getting lucky.

Were the reamers supplied with such dies (e.g., from RCBS) specialty reamers, or is there some source of reamers by the thousandth somewhere?


Thanks

https://www.precisionreloading.com/cart.php#!c=189

[ulav8r]

Reamers made to use with dies won't damage the die like a straight flute reamer would. Also the reamer provided with the die would maintain concentricity better.

[243winxb]

https://www.forsterproducts.com/product/standard-neck-reamers/

RCBS reamers/dies held the neck in a die, while reaming. Long gone.