30BR neck turning sanity check and questions

[Kevin1990]

So I'm going to be prepping my brass for my 30br next week, and I'm just looking for some confirmation and have a question or two.

My plan assuming everything goes smoothly. (It never does.)

Neck up using PMA 6mm-30cal expander mandrel

Bump shoulders back .010

Use PMA model B .011 for rough cut

Use PMA model B .010 for final cut (.332 neck)


QUESTIONS:
Does this process seem okay?

Also, how far down into the shoulder do I go? I'm seeing some conflicting information on this part. I've been watching videos and reading quite a bit. I saw this picture on the accurate shooter website. And then I watched a video on PMA and saw the picture posted. My cutter is a 30 degree angle. Is something like this inevitable. How far down do you go? Ill probably end up doing 1 or 2 and post on here for criticism.

Thanks fellas

 

[Bill Norris]

I did not cut into the shoulder. Just touching is fine in my opinion.

 

[AlNyhus]

The good thing about pushing the shoulder back is that the bottom of the cut becomes the 'blend' into the shoulder when the case shoulder blows forward. For a cutter, one with more angle than the exact angle of the shoulder helps eliminate an edge that can occur. For the BR case, I find a 35 degree cutter works well. The more runout there is in the expanded necks, the more wobbly your blend cut into the shoulder will appear. The way the Parosky cases look is the amount of blend I like to see. A carbide turning mandrel is a huge help, too.

Lots of ways to do this. Like a lot of things, it's the results that matter. -Al

 

[steve210]

You don't want to get in to the shoulder too much just right to the junction. There is practically no chance of ever seating a bullet that deep, unless you have a very strange combination. lol! Just do what Al said.

 

[Kevin1990]

The good thing about pushing the shoulder back is that the bottom of the cut becomes the 'blend' into the shoulder when the case shoulder blows forward. For a cutter, one with more angle than the exact angle of the shoulder helps eliminate an edge that can occur. For the BR case, I find a 35 degree cutter works well. The more runout there is in the expanded necks, the more wobbly your blend cut into the shoulder will appear. The way the Parosky cases look is the amount of blend I like to see. A carbide turning mandrel is a huge help, too.

Lots of ways to do this. Like a lot of things, it's the results that matter. -Al

Do you think you could accomplish parosky's cut with a 30 degree cutter, or should I really have a 35 degree? If so I'll just exchange the ones I have.

 

[J.D.Erwin]

Do you think you could accomplish parosky's cut with a 30 degree cutter, or should I really have a 35 degree? If so I'll just exchange the ones I have.

^^^ kevin990
your 30 degree will work just fine but like Bill and Al said cutting into the shoulder can be an issue

 

[Bob in WI]

Just checking ...most 30BRs have a neck of .330 on the reamer...if memory serves..?? .01 wall over a .308 bullet is .328 loaded dimension.. I think my math is working today..
Unless you are saying your necked up case is .332 before cutting..cause that sounds like a familiar number.

 

[AlNyhus]

.01 wall over a .308 bullet is .328 loaded dimension..

Don't forget the diameter of the bullets pressure ring. Some very good bullets will have a pressure ring around .3088. Suddenly, your .002 neck clearance becomes quite a bit less.....

 

[Kevin1990]

Don't forget the diameter of the bullets pressure ring. Some very good bullets will have a pressure ring around .3088. Suddenly, your .002 neck clearance becomes quite a bit less.....

Yep! So I had a conversation with you and a few others on here a few months ago, and you helped me realize I would have had a big problem doing it the way I was going to originally. My hottentstein bullets are .3088 along with Ammerman, and then the barts are I believe .3084 so with the final cut ill have .0032 for the fatties and .0036 for barts.

Just checking ...most 30BRs have a neck of .330 on the reamer...if memory serves..?? .01 wall over a .308 bullet is .328 loaded dimension.. I think my math is working today..
Unless you are saying your necked up case is .332 before cutting..cause that sounds like a familiar number.

I had mine done for a .332 neck I may have done my math wrong....uh oh.

Edit:
I did .010 x 2+.3088=3308-.332=.0032

is that the correct math for a .332 neck

 

[Kevin1990]

Yep! So I had a conversation with you and a few others on here a few months ago, and you helped me realize I would have had a big problem doing it the way I was going to originally. My hottentstein bullets are .3088 along with Ammerman, and then the barts are I believe .3084 so with the final cut ill have .0032 for the fatties and .0036 for barts.

I had mine done for a .332 neck I may have done my math wrong....uh oh.

Edit:
I did .010 x 2+.3088=3308-.332=.0032

is that the correct math for a .332 neck

EDIT. Just spoke with PMA tool. my math was off I believe. Hes going to set them up so I get around 3 thou neck clearance for the fatties.

 

[Bill Norris]

EDIT. Just spoke with PMA tool. my math was off I believe. Hes going to set them up so I get around 3 thou neck clearance for the fatties.

Yea you gonna need to be down at least around .329 loaded neck diameter with a .332 chamber neck. .010 - .0105 neck thickness should get you there.

 

[Kevin1990]

Yea you gonna need to be down at least around .329 load neck diameter with a .332 chamber neck. .010 - .0105 neck thickness should get you there.

That's why I come on here and ask the guys that make the big bucks! Thanks Bill. Luckily PMA didn't ship them out yet. He's setting them up for me. I blamed the NYS education system for my mathematical failure. I think he bought it. haha.

 

[Bill Norris]

That's why I come on here and ask the guys that make the big bucks! Thanks Bill. Luckily PMA didn't ship them out yet. He's setting them up for me. I blamed the NYS education system for my mathematical failure. I think he bought it. haha.

No worries at all. Now you got it figured out and ready to move on.

 

[AlNyhus]

Honestly, I've never turned necks by the 'math'. I turn them until they measure what I want over the pressure ring.

 

[Kevin1990]

Honestly, I've never turned necks by the 'math'. I turn them until they measure what I want over the pressure ring.

If I ever do another cartridge that needs neck turning I will probably do the same. Perhaps a 6ppc in the future. You broke it down simple enough in previous posts for me. I just over complicated it. thanks again

 

[Bob in WI]

Don't forget the diameter of the bullets pressure ring. Some very good bullets will have a pressure ring around .3088. Suddenly, your .002 neck clearance becomes quite a bit less.....

Just re-checked a couple 10X match bullets.
.3082 at the pressure ring. For my instance it's pretty much negligible. Guess I never realized others could be so much bigger at the ring

 

[LHSmith]

I always cut into the shoulder just enough that I could detect a step in the shoulder with a finger nail. On occasions when I went too far (like the first few when setting up the tool adjustment) I still used them and never suffered a detached neck with those cases.
On the neck-turning article of 4/22 in the Bulletin, "lubricants for turning mandrels", it mentions lubricants can work well on the outside of the necks. With brass, lube should not be necessary as it is free-cutting. If one has a non-carbide mandrel then the inside of the neck should be lubed.

 

[FNSafari]

I did not cut into the shoulder. Just touching is fine in my opinion.

Bill, IMO, the case may or may not chamber depending on the reamer specs.

 

[JEFFPPC]

Your making something simple hard. No reason to bump the shoulder back unless you want to dream one up. Do the math , cut a couple, load and measure at pressure ring as mentioned above. I cut into the shoulder about 1/16 . Does it work. I have a barrel approaching 8000 rounds that all but the last 180 shots have been on the original 150 pieces I made. So late last summer I made up some new brass just because. Yep,I saved the old brass.

 

[Bill Norris]

Bill, IMO, the case may or may not chamber depending on the reamer specs.

My reamer specs. does not dictate cutting into the shoulders. Never had an issue with chambering Lapua or Peterson brass.