I want to make a custom neck sizing die for .577 Snider

[corbinace]

Greetings,

As stated in the header I would like to make a neck sizing die for my .577 Snider. I am using 24ga brass shot shells as my donor brass.

I intend to do one of two things for my sizer die. Either a chucking reamer applied to a donor die or a drill bushing fitted into a donor die. I only need to size the neck, as the rest of case will chamber as is.

1) How much under size should I make the die to allow for spring back.
2) How much under size of the neck ID, for correct neck tension on a pure 100% lead projectile.

Numbers that we have to work with are:

0.649 Original case OD at neck area
0.009 Case wall thickness at neck area (remember x 2 for 18 total)
0.602 Bullet diameter
0.500 Neck length

As you can see we do not need to move very much. The issue that I think will come into play is the large diameter of the brass. It is easy to reduce small diameter brass and it stays pretty close to the size of the sizer. But I am thinking that this large diameter/thin wall will not take a set as readily as a smaller diameter/thicker wall.

Yes, I know CH4D would love to help me out, but I want to see if I can economically do it myself. Economically, means getting it right the first time, hence the query.

Thank you for your attention, Tim.

[fg-machine]

well you can almost forget about using a donor die and a bushing . there simply isn't enough room .
and don't forget to add in however much neck tension you desire .

i doubt spring back will be much of an issue and unless you already have a nice set of adjustable reamers i wouldnt bother .
use a boring bar to get you close and just finish it with a hone .

[corbinace]

well you can almost forget about using a donor die and a bushing . there simply isn't enough room .

Thank you FG , for pointing out that important fact. When posting, I had forgotten that I needed to get a 1-1/4-12 bolt and bore it to accept the drill bushing. The mind is a fragile thing, you know.

The boring bar idea is a good one, unfortunately, it is a bit above my current skill-set.

The adjustable reamer idea reminds me that somewhere I have an expensive adjustable reamer that I used for close tolerance 9/16" spar bolts a long time ago. I will hunt it up and see if it goes that large.

Thank you for the great feedback, a real help. Tim

[EDG]

You might think about the boring bar if you have a lathe. Get some scrap and practice. Small boring bars can only make small cuts but they are cheap and they will bore any size hole as long as it is not too deep. It just takes practice. I once bored the neck out of a Remington Hepburn chamber for a 40 2.5" Sharps. It was a ticklish job. By comparison the .577 will allow the use of a much heavier and longer bar. You can even grind a piece of tool steel to make a bar on the cheap if you don't mind a bit of grinding.

Thank you FG , for pointing out that important fact. When posting, I had forgotten that I needed to get a 1-1/4-12 bolt and bore it to accept the drill bushing. The mind is a fragile thing, you know.

The boring bar idea is a good one, unfortunately, it is a bit above my current skill-set.

The adjustable reamer idea reminds me that somewhere I have an expensive adjustable reamer that I used for close tolerance 9/16" spar bolts a long time ago. I will hunt it up and see if it goes that large.

Thank you for the great feedback, a real help. Tim

[country gent]

One other plus to the boring bar is it cuts a true hole round straight and on center, Drills can drift and reamers tend to follow the existing hole. I would recomend if you press is new enough to have the 1 1/2 12 - 7/8 14 bushing to use 1 1/2 12 bolt for die body or better yet a piece of pre hardened 4140 and single point the thread drill and bore die for case body in the same set up. drill a pilot hole clear thru the blank and true up the outside lightly when in the first set up. Reverse in the lathe and indicate in to your trued up section. bore for bushing to size the neck. with thin brass you may want to form necks in 2-3 steps down then on last form finish the shoulder. I would also recomend annealing cases at start and when finished. Sizing down thickens /shortens the brass so you may also need to neck ream neck turn finished brass. A rented chamber reamer might be very usefull to do die body shoulder. The bushings can be held in with a cap threaded into die body.

[dragonrider]

If I were doing this I would only bore the neck and shoulder into the die, don't see a need to cut the full length of the case.

[Frank46]

If your press has an insert for larger dies then may I suggest getting a piece of threaded rod of the same thread. Or better yet some screw machine stock. I bought some 7/8x14 threaded rod from a machine shop supply house years ago. Machines and cuts good and can be reamed and polished easily. Do not get any hardened bolt or cadmium plated stuff from the big box stores. Likely from china and would be junk. Frank

[Idz]

some suggestions from my building MH 577/450 case forming dies.
1) I used 7/8-14 threaded rod. Hardening isn't necessary for doing only a hundred or so cases.
2) The Magtech cases are so thin you must support the entire case when forming or else it will crumple.
3) To make it easy to machine make the die in two pieces. Neck & shoulder in one piece and body in the other. Make sure the shoulder is a few thousands larger in diameter than the top of the body so the case slides in easily.
4) Liberally lube the cases.
5) If case being formed seems to stick a bit then back off, re-lube, and rotate it in the shellholder.
6) Anneal the neck area to soften the brass but don't overheat it.

good luck, even doing all this occasionally a MH case will still wrinkle.