Forming 338 from 300 Win Mag brass

[Pathfinder76]

Has anyone done this? I can do it. They look right, but I’ll be darned if I can get them to chamber properly. Does anyone have any secrets?

[Dean2]

Originally Posted by Pathfinder76

Has anyone done this? I can do it. They look right, but I’ll be darned if I can get them to chamber properly. Does anyone have any secrets?

Are you perhaps forgetting to trim the formed 338 to proper length. 300 WM are 2.62, 338 is 2.50. They actually get longer when you neck up, and the necks get thinner, usually. If you aren't trimming they will bind on the chamber neck cut. The bolt will close but it will be a tough go.

[fps plus]

Possibility that the necks are too thick . Can you chamber one of the formed brass with out a bullet loaded. Or you are not setting the shoulder back far enough. Check trim length.
Maybe easier to expand 7 mm rem mag brass

[Pathfinder76]

No, I’m trimming them to the proper length. It might be the neck thickness. I was going to try to use Lapua cases (so no 7mm) but want to be darn sure I have this figured before I order $200 worth of experimental brass.

[Pathfinder76]

I do think it’s the bottom 2/3 of the neck causing problems.

[Dean2]

Smoke or black the case and see where it is rubbing off. I have never seen necking up make the shoulder or neck thicker. It is possible that pulling the expanded button out the neck is pulling it forward. Try trimming the case before sizing, run it through the sizing die but lube inside the case mouth with imperial wax. . Test fit that case.

[Homesteader]

Or you could just buy these.

https://www.eaglefirearms.ca/winches...med-brass.html

https://northprosports.com/index.php...roduct_id=8363

[Pathfinder76]

Originally Posted by Homesteader

Or you could just buy these.

https://www.eaglefirearms.ca/winches...med-brass.html

https://northprosports.com/index.php...roduct_id=8363

There are lots of places you can buy domestic brass for $90. I am just thinking it’s immoral.

[Pathfinder76]

Originally Posted by Dean2

Smoke or black the case and see where it is rubbing off. I have never seen necking up make the shoulder or neck thicker. It is possible that pulling the expanded button out the neck is pulling it forward. Try trimming the case before sizing, run it through the sizing die but lube inside the case mouth with imperial wax. . Test fit that case.

In this case (no pun) you are more than just necking up. You are pulling the shoulder into the neck.

[elkhunter11]

Originally Posted by Homesteader

Or you could just buy these.

https://www.eaglefirearms.ca/winches...med-brass.html

https://northprosports.com/index.php...roduct_id=8363

After using a recent batch of Winchester cases, I will be avoiding them whenever possible, the quality has sure fallen off.

[DLab]

Necking up using a die expander button will pull material from the shoulder into the neck making a donut at the neck base, using an expander mandrel has less of an effect. You can usually see the donut ring.
Makes them hard to chamber.

[Pathfinder76]

Originally Posted by DLab

Necking up using a die expander button will pull material from the shoulder into the neck making a donut at the neck base, using an expander mandrel has less of an effect. You can usually see the donut ring.
Makes them hard to chamber.

This is what I’m thinking. This 338 was going to be simple I told myself. Load RP brass with standard dies, you know the drill. It’s the only caliber I do not have mandrels for. But I ordered a PMA mandrel for it last week. I’ll see if that helps when it arrives.

[DLab]

Necking up with Mandrels in multiple steps rather than one expander ,even an elliptical expander, works much better for minimizing the donut.
Tested this myself expanding 6br. to .30 just a few weeks ago after getting PMA Mandrels in .284.
6 to 6.5 to 7 to 30 also I think it work hardened the brass less and helped with concentricity, firing straightens them anyway.

[Dean2]

I have made 460 from 378, 338 from 300 and 7 mag, 338 Fed out of 308 and 8x57 out of 7x57, plus a wack more. I have never owned a Mandrel to do any of those. I have also made 338-378 out of 460 Bee, 17 HH out of 22 H, 243 out of 308, 7-08 out of 308 and a bunch of other neck downs. Same thing, always just used the seating die followed by the FL sizer. For big step downs I have often used an interim step with the seating and sizing die, so 460 bee to 378 seater, then FL 378 then 338-378 seater, then FL. All have been done with just standard dies. I have never had issues with donuts necking up. On some of the neck downs I have had to trim down over thick necks. If you guys are getting the donuts I can see why you want mandrels and inside neck reamers. Also, donuts, if not reamed out, will definitely cause the brass to bind at the neck shoulder junction when chambering a round. Let us know how it works out.

[aardvaark]

Originally Posted by elkhunter11

After using a recent batch of Winchester cases, I will be avoiding them whenever possible, the quality has sure fallen off.

Ditto that! Tried Winchester brass with two different calibers, after all, it’s Winchester it should be good. The second bag was so bad I could only salvage 2 out of 3 so I sent them back, got a full refund.

[Homesteader]

Originally Posted by elkhunter11

After using a recent batch of Winchester cases, I will be avoiding them whenever possible, the quality has sure fallen off.

That's too bad, it used to be really good brass for me, but that's a decade or two ago. Now I'm a bit of a snob, mostly lapua or norma for me. If I had it I'd still load it though. Inside 300 yds, I don't think I can take advantage of it from an accuracy stand point but if it's false economy that's unacceptable too.

Pathfinder, everything is getting silly expensive now, but I agree $90 for 50 WW cases is too much. That's high for laupa to me, but it is what it is in this economy.

[Dean2]

I have always been a big WW brass fan. Sad to hear it has gone down the crapper like so much US made stuff the past few years. Made in America doesn't mean the same as it used to. Probably blaming that on Covid too.

[Homesteader]

http://www.outdoorsmenforum.ca/showthread.php?t=407882

Better snap it up!

[brewster29]

Originally Posted by Homesteader

http://www.outdoorsmenforum.ca/showthread.php?t=407882

Better snap it up!

That’s a lot easier…

Shame about issues with WW brass, back when I started loading seriously in the late 80’s it was the best brass available for hardness. RP and Norma were quite soft then.

[Pathfinder76]

Well, I’ve solved it. But it took two dies to do it. One to size the neck enough and one to bump the shoulder enough. My die was not getting the neck enough and the other one won’t bump the shoulder enough. Both are Redding FL dies.

[Dean2]

Originally Posted by Pathfinder76

Well, I’ve solved it. But it took two dies to do it. One to size the neck enough and one to bump the shoulder enough. My die was not getting the neck enough and the other one won’t bump the shoulder enough. Both are Redding FL dies.

Glad to hear you got it figured out and thanks for the update. Kind of surprised at what caused the issue. Think I would be sending those dies back to Redding. Stay well.

[DLab]

Glad you got it figured, bit of a PITA but it works, maybe FL bushings dies needed?
With the backup and supply issue Redding has going on currently, I'd be sure to have another die that works before sending those back, you likely wouldn't be seeing anything in the way of a replacement for months down the road.