• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

turning necks on 338

P1ZombieKiller

Silver $$ Contributor
if you are turning necks on 338 brass, I would love to know the equipment that you are using.
I have everything for 6 and 30's, but the 338 mandrels I have don't seem to fit properly.
 
I have built a 338 wildcat based on the 6br case. When neck it up that much, the shoulder junction has too much of a lip, and it needs to be turned down.

I neck up to 308, and can turn them fine (basically a 30br case)

When I neck the 30br up to 338 ( with the 338 expanding mandrel that is supposed to match the turning mandrel), the turning mandrel doesn't fit smoothly. Its too tight of a fit.

I need to find someone that has a matching 338 mandrel set and buy the same brand/size they are using.
 
There is always spring back when sizing brass. Up and down. Sounds like you just need a larger expanding mandrel.
I get it, but the "spring back" on all 7 of my other cutters seem to be a perfect fit with the matching turning mandrels.
Why not this one?

they are the same brand as my other one's.
 
Wes, try taking an old 30BR barrel and ream the neck out to .338.
Then fire a full house 30 BR )before turning the neck) in it and I bet a beautiful formed 338BR will come out, ready to neck turn.
 
zombie killer,

I've used a 0.322" (8mm) mandrel to expand some 0.308" cases before sizing them down and then expanding to 0.308" for turning

I use the K&M tools and expander for 0.308" and 0.338". I don't know what the next size up for 0.338" would be, but a 0.358" mandrel would be close enough to work. Turned the $15 mandrel down to where the cartridge mouth is a good slip-fit over the carbide turning mandrel.

HTH,
DocBII
 
zombie killer,

I've used a 0.322" (8mm) mandrel to expand some 0.308" cases before sizing them down and then expanding to 0.308" for turning

I use the K&M tools and expander for 0.308" and 0.338". I don't know what the next size up for 0.338" would be, but a 0.358" mandrel would be close enough to work. Turned the $15 mandrel down to where the cartridge mouth is a good slip-fit over the carbide turning mandrel.

HTH,
DocBII
If I had a little lathe that would be perfect, but I dont. I think i will contact @DJSBRS to see if he can do it.
 
I have built a 338 wildcat based on the 6br case. When neck it up that much, the shoulder junction has too much of a lip, and it needs to be turned down.

I neck up to 308, and can turn them fine (basically a 30br case)

When I neck the 30br up to 338 ( with the 338 expanding mandrel that is supposed to match the turning mandrel), the turning mandrel doesn't fit smoothly. Its too tight of a fit.

I need to find someone that has a matching 338 mandrel set and buy the same brand/size they are using.

Have you tried necking up a single piece of brass and immediately going to neck turning? It helps with the spring back issue.
 
my process is:

6br brass, neck up to 308
turn brass to .010" (essentially a 30br brass)
expand to 338

I have shot this rifle 100+ times with brass made from this process using brass from one of my old 30br barrels.

My problem is (and I know better) is I took brass from this old barrel, and brass from that old barrel and they are all mixed together. Some have been fired 6 times, some 18 times.
I have no idea which ones are which and I think I need to start all over with new brass.

This rifle is only a subsonic "pig thumper" so I consider it a hunting gun.
So I didn't think brass consistency was that big of an issue.

20250328_092057.jpg
 
I forgot to add, That Hornady has just released their new 338 SUB X bullet and I am going to use those instead of match bullets. Those SUB X bullets are designed to expand even at 900 fps.
So I want to start off with new virgin brass and keep 150 pieces in rotation.
 
Last edited:
If I had a little lathe that would be perfect, but I dont. I think i will contact @DJSBRS to see if he can do it.
zombie killer,

I didn't use a lathe for anything, just a drill. Just diamond boards and patience. Only removed a couple of thousandths from the mandrel. Took less than an hour.

HTH,
DocBII
 

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Forum statistics

Threads
166,984
Messages
2,226,246
Members
80,084
Latest member
H3NN13
Back
Top