outside neck turning vs reaming

[MarkR]

O.K. You guys know that I'm new to BR shooting so humor me on this one and I'll listen to the answers.
Why is outside neck turning superior to inside neck reaming. It just seems to me that if one has a proper die made so that the reamer and brass are captive and cuts to the proper inside diameter...that would satisfy the neck wall thickness needs just fine. I use this system on my 12, 14 and 17 cal. ammo and it seems to work just fine.
Enlighten me on this

 

[Charles E]

. . . It just seems to me that if one has a proper die made so that the reamer and brass are captive and cuts to the proper inside diameter...that would satisfy the neck wall thickness needs just fine. . . .

Yes, as long as "captive" means held so tight that the reamer will not simply follow the hole, but act like a boring bar. T.J Jackson use to bore necks on a lathe. Must have been a good one!

For one of my wildcat chamberings which is both necked down and has the shoulder pushed back, I made up a die that has a hardened drill bushing used as a pilot in the top of the die. I use an exact size chucking reamer in it. This simply because with our lathe, I can't think of a way to accurately bore necks on the chamber centerline. The die started out as a Wilson seating blank, with that nice reamed hole all the way through. We used a FL die reamer to ream the chamber part of the die (to hold the case firmly) and machined the top to take the hardened bushing. All set up on that nice reamed hole. We threaded the die so it can be used in a press, cases are seated with all the force a Rockchucker can apply. They don't move. Neither will the chucking reamer. I can tell from how brass is removed that the reamer is not simply "following the hole."

A lot of work to make the die, and a fair bit to use it.

BTW, I still neck turn. The reaming/boring is just to ensure the hole in the case is true to the centerline of the chamber, which in turn is true to the centerline of the bore in the barrel. If you are starting with good brass (little wall thickness variation), and not doing something like pushing the shoulder back a lot, there is no need for all this work.

BTW2, a Wilson trimmer just has too much clearance in both the case holder and the part that supports the reamer to work like this.

There are a few people who feel that the finish on the inside of the neck just as it comes is important. I'm not one, but who knows?

 

[amamnn]

I use both methods depending upon what cartridge I am working with. For an example, if I am necking up a 6BR case to 30 BR, I have to turn since the dreaded doughnut forms on the outside. Otherwise, I mostly ream if I have to cut into a neck. Since going to mostly the "no turn" chamberings, I don't do a lot of turning or reaming other than noted above..

I'm sure there are many other people who would never ream--or bore--but it's the way I learned and it allegedly avoids the DD that can form on the inside of the neck.....

 

[Big Al]

This question has forgotten what you are trying to do and what you are doing it for. You have a bullet of a given diameter, if the outside of the neck is to thick, what is it to thick for? To fit what? To fit the inside of the neck to what? It's not the bullet, is it? Could it be for a chamber neck? The bullet needs to be a certain size to allow the bullet to enter the neck of the ctg.. If the inside of the neck is to small to allow the bullet to enter the neck of the ctg, would material have to be removed? And if the diameter on the outside of the case was to large to enter the chamber of the rifle, would material need to be removed?


One has nothing to do with the other. You are talking about two different things.

 

[MarkR]

This question has forgotten what you are trying to do and what you are doing it for. You have a bullet of a given diameter, if the outside of the neck is to thick, what is it to thick for? To fit what? To fit the inside of the neck to what? It's not the bullet, is it? Could it be for a chamber neck? The bullet needs to be a certain size to allow the bullet to enter the neck of the ctg.. If the inside of the neck is to small to allow the bullet to enter the neck of the ctg, would material have to be removed? And if the diameter on the outside of the case was to large to enter the chamber of the rifle, would material need to be removed?


One has nothing to do with the other. You are talking about two different things.

To transform 220 Russian brass into 6PPC , commonly available tooling has you push a mandrel into the neck of the case and expand the interior of the neck to around .243, which forces you to turn the outside of the neck wall to whatever thickness is necessary in order to fit in your chamber. I guess that my thinking was to use a mandrel to expand the neck o.d. to the proper size and then ream the i.d. to the diameter necessary to provide proper neck tension on the bullet. This would help to preclude the forming of a doughnut on the interior of the neck/shoulder junction. I guess that my thinking is backwards compared to popular methods.
I have inside neck reamed during the case forming process for years while making brass for several wildcats, although they aren't chambered to the precision specs of a br rifle, they are chambered by professionals with custom spec reamers, and inside reaming has not given me any problems so far.

 

[Butch Lambert]

Why not fireform first without a bullet? Inside ream, expand just slightly and then turn. I'm speaking 6PPC. I bought a reamer from MSC that will just cleanup the ID of the neck. You only have to expand the ID very slightly before OD neck turning. Everybody talks about working in tenths and I don't think that you can make a setup that will inside ream and leave the inside of the neck concentric to the OD within .0004 without doing your final cut with the outside turning.
Butch

 

[MarkR]

Why not fireform first without a bullet? Inside ream, expand just slightly and then turn. I'm speaking 6PPC. I bought a reamer from MSC that will just cleanup the ID of the neck. You only have to expand the ID very slightly before OD neck turning. Everybody talks about working in tenths and I don't think that you can make a setup that will inside ream and leave the inside of the neck concentric to the OD within .0004 without doing your final cut with the outside turning.
Butch

Butch, I think thats a good idea! I am talking about having a size/ream die made to hold the brass firmly while being reamed, that may be too much expense and trouble though. I find myself in a predicament by not having a fireforming barrel yet and I'm just trying to get the brass where it needs to be without messing up too much of it.
So, you suggest that I take raw Lapua 220 Russian brass, which I have already sized to 6mm, run it through my sizing die to fit my 262 neck chamber, fireform, expand with a mandrel, turn to final size and shoot it for the first time?
I think my first mistake was to expand the new brass to 6mm first.

 

[Boyd Allen]

As to the ream vs turn question, I have a tight necked .222 that I tried reaming and turning...both, first reaming in a custom die, and then turning. The reaming did not hold neck thickness runout nearly as close as turning, and it really roughed up the inside of the necks until a couple of shots were fired. I stopped reaming and settled on truning only. There is theory, and then there is actual experience.

 

[Al Nyhus]

BTW, I still neck turn. The reaming/boring is just to ensure the hole in the case is true to the centerline of the chamber, which in turn is true to the centerline of the bore in the barrel. If you are starting with good brass (little wall thickness variation), and not doing something like pushing the shoulder back a lot, there is no need for all this work.

BTW2, a Wilson trimmer just has too much clearance in both the case holder and the part that supports the reamer to work like this.

There are a few people who feel that the finish on the inside of the neck just as it comes is important. I'm not one, but who knows?

Hi Charles. Just a few thoughts to add on the Wilson setup:

I agree that if the main concern is to recenter the case neck id. relative to the centerline of the case body (if working with lopsided case necks after some serious reforming, for example) a lathe and a supported die is probably the way to go.

In a scenario where the necks are in line and the case neck i.d.'s simply need to be reamed to a uniform dimension, the Wilson setup can give excellent results, given a bit of forethought and some minor work before the case ever gets cut.

Hope all is well with you. Good shootin'. -Al

 

[Butch Lambert]

Mark, Don't size your brass first. Just put a primer, a little bit of Bullseye powder in the case, and seal with wax. Shoot it! I didn't have Boyd's experience with it being rough inside the neck. If you choose to ream, do it now and then expand the necks and uniform the cases to length. Now you can neck turn.
Butch

 

[amamnn]

I agree that I did not find that reaming made the inside of my necks rough. Anyway, I 'm going to fire form the cases before I'm finished, rough or not.