6 UM or 6-7PRC?

[Jimbee]

Does your press cam over?


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No. Maybe I need a different shell holder?

 

[BjornF16]

No. Maybe I need a different shell holder?

Which cartridge die are you using?

Are you using Hornady bushing?

If the die is setup correctly, you should be bumping shoulder and getting nearly 100% neck sizing. Do you have the spindle collar lock screwed in all the way? (Upper circle in diagram below)

 

[Jimbee]

Which cartridge die are you using?

Are you using Hornady bushing?

If the die is setup correctly, you should be bumping shoulder and getting nearly 100% neck sizing. Do you have the spindle lock screwed in all the way? (Upper circle in diagram below)

View attachment 647593

I'm using a 7PRC bushing die. I think the dies are RCBS. Spindle is all the way in.

 

[BjornF16]

I'm using a 7PRC bushing die. I think the dies are RCBS. Spindle is all the way in.

Ok…let’s backup.

What press are you using? Hornady?

Are the dies you’re using FL or Neck sizing only?

 

[Jimbee]

Ok…let’s backup.

What press are you using? Hornady?

Are the dies you’re using FL or Neck sizing only?

I have a Lyman press, Hornady full length, Match Grade bushing die, RCBS? bushings, Lyman shell holder?
I appreciate the help.

 

[BjornF16]

I have a Lyman press, Hornady full length, Match Grade bushing die, RCBS? bushings, Lyman shell holder?
I appreciate the help.

I suspect your issue is mixing the RCBS bushing with Hornady die.

If your Hornady die spindle collar is fully seated and you’re bumping the shoulder, then I would bet the RCBS bushing is shorter than a Hornady bushing.

 

[Jimbee]

I suspect your issue is mixing the RCBS bushing with Hornady die.

If your Hornady die spindle collar is fully seated and you’re bumping the shoulder, then I would bet the RCBS bushing is shorter than a Hornady bushing.

What size die are you using?

I suspect your issue is mixing the RCBS bushing with Hornady die.

If your Hornady die spindle collar is fully seated and you’re bumping the shoulder, then I would bet the RCBS bushing is shorter than a Hornady bushing.

What size die are you using? Do you use an expander with your bushing die? Can you measure the length of your die?

 

[BjornF16]

What size die are you using?
What size die are you using? Do you use an expander with your bushing die? Can you measure the length of your die?

Just to be clear, I’m not running a 6-7PRC (yet).

I’ll wait until @Ryan Avery assesses and compares to the 6UM (as well as seeing if 6 UM gets head-stamped brass)

 

[longrange13]

My bushing die doesn't size the whole neck. What am I doing wrong?View attachment 647515

I’m not 100% sure, I don’t have a ton of experience necking down brass. I’m using Redding type-s full length bushing dies. If I had to guess you don’t have the die ran down far enough. Mine are set up to push the fired shoulder of my 7prc back about .003”. I ran it through a 6.5 bushing and then a 6mm bushing with my die set just like I resize for my 7prc. It’s a bit more cam over on the press than you’d expect. A lot of people who don’t have the comparators to measure shoulder bump usually don’t bump their shoulders hardly at all. They’ll squeak out a couple reloads and then not be able to chamber their brass.

 

[khuber84]

Necking down brass with a bushing die, is always going to leave a donut of some kind at the base. Using whidden bushings create less, as they don't have as much bevel at the base of the bushing. Having some donut isn't that big a deal as long as the round chambers, it'll fireform out. I just built a 6saum this fall, and it had the same donut after neck down, it was gone after firing. Same with my 22br, disappeared after first firing.

The way to remedy this is to use a neck sizing die. Hornady makes em, but they're not for magnum diameter cases, just 308/br style cases, at least the ones I've found. When I built a 25 Saum 4 years ago, I used a 25wssm FL sizing die to neck down the 65saum parent, no donut. I guess a guy could try using a 243wssm FL sizing die, to neck down the 7prc. I'd use an intermediate step first with a bushing, say a 295 diameter or so, prior going straight 6mm. I recently just neck turned and necked down a bunch of 7saw brass I'll be forming in a deep headspace 25 creed chamber. I'm actually going to use the donut at the neck down area as a false shoulder for fireform. Lots of ways to do this, but most the bulge is cosmetic and will be gone after first firing.

 

[GoatPackr]

@Ryan Avery I think you should skip the 7PRC and use a .277 Fury for the next 6mm super magnum.

Kris

 

[Ryan Avery]

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[Jimbee]

I suspect your issue is mixing the RCBS bushing with Hornady die.

If your Hornady die spindle collar is fully seated and you’re bumping the shoulder, then I would bet the RCBS bushing is shorter than a Hornady bushing.

The fix was switching to a Hornady shell holder.

 

[khuber84]

@Ryan Avery I think you should skip the 7PRC and use a .277 Fury for the next 6mm super magnum.

Kris

Just ordered 200x pcs of hybrid cases for the 277fury. I see some wild experiments in my near future!

 

[UM GM]

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Geeez--I just texted you that pic. I was wondering if you had seen it. I guess so........................

 

[longrange13]

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Ryan, what are you going to use for dies on this project?

 

[Ryan Avery]

Ryan, what are you going to use for dies on this project?

7 PRC bushing die

 

[longrange13]

7 PRC bushing die

What brand of seating die? I wanted to use my Redding competition 7prc die for it, but Redding won’t build a .243 seating stem for it.

 

[Axlrod]

I am in the process of building a 6 ROKUM (go ahead and trademark the name!)
Hope to send my stuff to UM next week.

For dies I have Hornady match grade bushing. I put a Horn. 6mm A-Tip stem in the seater and have Redding coated bushings (.271,.272,&.273) for the resize. I am also going to order a Wilson inline seater in 7 PRC and use a 6mm VLD stem.

I sized some 7 PRC ADG brass first with a .285 then a .271 bushing. With a 115 Dtac this yielded .004 neck tension.

Maybe @Ryan Avery could start a 6 ROKUM reloading thread?

 

[BBob]

My bushing die doesn't size the whole neck. What am I doing wrong?

Like it or not that’s a feature on many bushing dies, not a bug. Common on many bushing dies. Redding for another.