RCBS and Redding resize dies -Vs- Hornady resize die.

[Texas Sheepdawg]

AKA….. The quest to get rid of fat shouldered 450 bushmaster cases, and get them back down to spec.
Die sets.
The RCBS 450 Bushmaster 3 Die Set # 21604 Group C Dies
Manufacture date, 11/22/22.
RCBS Shell Holder # 3 part # 09203
And.
Redding Full Die Series D 450 Bushmaster #91781

Being used on about seven different oversized 450 bushmaster cases that have been once fired or more, and would no longer fit my chamber gauge even after being cleaned decapped and resized in my Hornady 450Bushmaster resize die that I bought back in 2011-2012.

I made a small movie however I cannot publish it on my YouTube channel because I’m having issues with my video editing software on my computer. So I’ll try to put in a few images and I’ll get to the video as soon as I can figure out what the heck is going on with my Mac.
So earlier this year, or may be around Christmas, we were having discussions about once fired cases, no longer being in spec after being fired once or twice. And it seemed the Hornady resizing die just couldn’t get down deep enough to resize the area of the case head.
Well, I’m pleased to tell you that the RCBS Die and/or the Redding Die being used along with the RCBS #3 shell holder have resolved my fatty case heads.
The RCBS die did a perfect job of getting the case resized down far enough to remove the little hump in the area of the case head. The redding die was also effective however, the redding die was a bit strange. It seems that Redding has a different interpretation of the 450Bushmaster case specifications than most other manufacturers. It’s almost as if they are trying to insinuate a shoulder up on the 450Bushmaster cartridge. Once I post pictures you’ll understand.
Of course, the caveats are going to be that you are going to have to recheck the case length after resizing, and you need to keep a close eye on your cases for case head failures. You will need a special measuring tool for that, and I’m trying to do some research on what that tool is called and where they are available. but you have to be able to measure down into the case down close to the case head/ the wall thickness of the case to look for thinning of the case wall. Once you start to see that signature, the case will no longer be usable because it could separate. That’s what they call case head failure. This failure is discussed at the beginning of all of your reloading manuals. Overall, though, I am pleased with the results of both of these dies. Especially the RCBS. The Redding die however kind of has me scratching my head and leads me to believe that maybe I might want to use this die for prepping cases for the .451 caliber bullets instead of the .452 caliber bullets.
But after properly, lubricating and resizing, all seven of these seemingly oversized, useless cases, both dies, have successfully put these cases back in to play again.
As for the Hornady resizing die?
I’m afraid my friends that that die will no longer be used on my bench.
If anyone at Hornady is reading this post, the resizing die I have is out of spec or defective as it does not fully resize the cases.
-OR-
The Hornady shell holder is too thick, and the dye does not get to reach its full potential down onto that area of the case that needs to be resized. And I have used two or three different brands of shell holders including two different Hornady shell holder’s and alignment shell holder, and then I have another one that I don’t know what brand it is. I guess I could try to find some more Fattys in my collection and put the Hornady dye back in the press and use that are CBS shell holder and see if my results would be different.

[Texas Sheepdawg]

BeforeRCBS

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AfterRCBS

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Die Mark RCBS

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[Texas Sheepdawg]

Before Redding

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After Redding

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Close up Post Redding

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[Hoot]

My issue was more at the .200 point above the case head, not the shoulder, using the same Hornady die set that you bought. Not always but occasionally, I'd get a case with too much CHG. My solution was to take one of the shell holders (I had several) that fit the 450b, chuck it carefully in my mini-lathe and face the top down as far as I felt was not compromising the strength and that allowed me to run the case just a little bit further up into the sizing die. That did the trick and I got a little bit more neck tension for my trouble.

Hoot

[Texas Sheepdawg]

That’s why I want to test some fattys with this # 3 shell holder and the Hornady Die. I don’t have any laying around at the moment however I’m sure I’ll run into a few if I dig around. When setting up my dies I always make sure the die is touching the face of the shell holder then I adjust the decapper rod accordingly. Usually though, I’ve already decapped them with my old press that’s using a universal decapping die.
What bugs me the most is that stepping configuration of the Redding die. It’s actually not even attempting to have a progressive tapering down to the case mouth. It reduces in tiers. Not visible to the eye, except at the case mouth where the final tier reminds me more of a 32-20 Winchester shoulder. LOL. But the digital caliper sure sees it.

[coyote wacker]

Thanks for doing some very interesting research !

When I started reloading and for many years RCBS was my go to loading dies....then back around 2000 I needed a set of dies and the only ones available were Hornady tried them and they seamed a little nicer in the machining so I've been buying them since....
With the 450 BM Hornady where the only dies available so that's what I've been using....