Case Neck Concentricity

CoyDog · November 7, 2001, 02:20 PM

I have been trying to track down some bullet runout problems using an RCBS CaseMaster Gauge, and have been able to narrow it down to case neck concentricity problems.

Specifically, I am getting .004 - .005 neck runout after resizing new .223 cases. The cases have only .001 to .002 runout out of the box. I can partially resize them in the FL die without the expander rod, and they still measure .001. When I use the expander rod and button, however, I am getting the .004+ runout problems. I'm using RCBS dies, have polished the expander button, and use Hornady One-Shot for case lube. The expander rod doesn't appear to be crooked.

I'd like to hear some ideas from experienced reloaders. Are there dies with a floating expander button which would work better? Is there a way to better adjust the RCBS expander rod/button?

I realize that .005 runout may not cause major problems with hunting accuracy, but it cheeses me off to take a perfectly concentric case and screw it up during the sizing process. Appreciate any suggestions.
Thanks,
CoyDog

C.R.Sam · November 7, 2001, 02:50 PM

Clearances and tolerances may stack for you or against you.

If your expander rod has lock nut.....might try losening the lock, runnin a known true case all the way in, rotating the expander rod half a turn or so and re-locking. Lock nuts often tend to cock things. Lot of times if you fiddle with all the variables, you will find a sweet spot.

Always a bummer when one tries their best and manages to make good things worse when the object was to make good better.

Sam

bk40 · November 7, 2001, 05:53 PM

Place an o-ring between the press threads and bottom of your FL die. The o-ring lets your die float itself as concentrically as possible.

Without going to custom dies, you can use the Redding die that sizes necks with a bushing rather than an expander button.

Big Bunny · November 7, 2001, 09:34 PM

Coydog -have you tried outside neck turning all your cases? Your problem could be a metal thickness problem in the necks. You will be horrified at what ammo "within manufacturers' tolerances" is sold to us unsuspecting shooters !
My problem ammo 'wobbles' disappeared when I did so, but quite a bit of brass fell on the floor from lall the lopsided case necks.

So your press and dies may not need adjusting atall.

But for less money [I am told] the Lee 'Factory Crimp Die' will do the "same job" by neatly mangling the case by crimp and truing up in this way ?!

The only case which was AOK and not touched by my "brass-shaver" was the superb Remington made little .17 case - [at 90c AUD each !!].
All the rest were very poor and even felt different when bullet seating was carried out.

BB

swifter... · November 7, 2001, 10:17 PM

The expander button has caused more run-out than: Insert favorite groaner...

Cheap answer: Lee Collett neck sizer. Size, turn 90*, size again.

More expensive: Redding Bushing die.

Note that with both, the force is exerted straight down on the case. With "expander ball" dies, it is down, then up.

The "O" rings will help. A small "O" ring to allow the expander ball/decap stem to center itself is useful too.
Tom

CoyDog · November 8, 2001, 10:37 AM

Appreciate the responses and good ideas to try. This board is like having a grizzled old reloader next door to hit up for advice when you run into a snag. I'll start with the O-rings and see what happens.
Thanks,
CoyDog

Big Bunny · November 9, 2001, 01:05 AM

Still feel half the problem may be uneven brass thickness, But please keep us all posted on your success or otherwise.
BB

Bogie · November 9, 2001, 11:26 AM

Disclaimer: I shoot benchrest

Gitcherself a Redding, or other, die that uses a sizing bushing. Your brass won't stretch as much either.

Assuming a factory chamber, you're not going to get a great deal out of neck turning.

I use Lee collet dies on my varmint rifles. They work very nicely. I seat the bullets with Wilson (or for my 6PPC, a Carstensen) in line seaters. If you don't want to do that, just go buy the Redding.

November 7, 2001, 02:20 PM	#1
CoyDog Senior Member Join Date: December 15, 2000 Location: Wyoming Posts: 163	Case Neck Concentricity I have been trying to track down some bullet runout problems using an RCBS CaseMaster Gauge, and have been able to narrow it down to case neck concentricity problems. Specifically, I am getting .004 - .005 neck runout after resizing new .223 cases. The cases have only .001 to .002 runout out of the box. I can partially resize them in the FL die without the expander rod, and they still measure .001. When I use the expander rod and button, however, I am getting the .004+ runout problems. I'm using RCBS dies, have polished the expander button, and use Hornady One-Shot for case lube. The expander rod doesn't appear to be crooked. I'd like to hear some ideas from experienced reloaders. Are there dies with a floating expander button which would work better? Is there a way to better adjust the RCBS expander rod/button? I realize that .005 runout may not cause major problems with hunting accuracy, but it cheeses me off to take a perfectly concentric case and screw it up during the sizing process. Appreciate any suggestions. Thanks, CoyDog __________________ "A man's choice of weapons is a portal into his thoughts, his values, and his character."

November 7, 2001, 09:34 PM	#4
Big Bunny Senior Member Join Date: August 9, 1999 Location: New South Wales - Australia Posts: 605	Coydog -have you tried outside neck turning all your cases? Your problem could be a metal thickness problem in the necks. You will be horrified at what ammo "within manufacturers' tolerances" is sold to us unsuspecting shooters ! My problem ammo 'wobbles' disappeared when I did so, but quite a bit of brass fell on the floor from lall the lopsided case necks. So your press and dies may not need adjusting atall. But for less money [I am told] the Lee 'Factory Crimp Die' will do the "same job" by neatly mangling the case by crimp and truing up in this way ?! The only case which was AOK and not touched by my "brass-shaver" was the superb Remington made little .17 case - [at 90c AUD each !!]. All the rest were very poor and even felt different when bullet seating was carried out. BB __________________ Bad boys, bad boys...watcha goin' to do - watcha goin' to do when they come for YOU ?!

November 7, 2001, 10:17 PM	#5
swifter... Senior Member Join Date: March 16, 1999 Location: So. CA Mountains Posts: 540	The expander button has caused more run-out than: Insert favorite groaner... Cheap answer: Lee Collett neck sizer. Size, turn 90*, size again. More expensive: Redding Bushing die. Note that with both, the force is exerted straight down on the case. With "expander ball" dies, it is down, then up. The "O" rings will help. A small "O" ring to allow the expander ball/decap stem to center itself is useful too. Tom __________________ There are damn few situations so screwed up that adding government to them will not make 'em worse... The best homeland security is an armed & informed citizenery! Molon Labe!

November 8, 2001, 10:37 AM	#6
CoyDog Senior Member Join Date: December 15, 2000 Location: Wyoming Posts: 163	Appreciate the responses and good ideas to try. This board is like having a grizzled old reloader next door to hit up for advice when you run into a snag. I'll start with the O-rings and see what happens. Thanks, CoyDog __________________ "A man's choice of weapons is a portal into his thoughts, his values, and his character."

November 9, 2001, 01:05 AM	#7
Big Bunny Senior Member Join Date: August 9, 1999 Location: New South Wales - Australia Posts: 605	Benchrest .223? Still feel half the problem may be uneven brass thickness, But please keep us all posted on your success or otherwise. BB __________________ Bad boys, bad boys...watcha goin' to do - watcha goin' to do when they come for YOU ?!

November 7, 2001, 02:50 PM	#2
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Clearances and tolerances may stack for you or against you. If your expander rod has lock nut.....might try losening the lock, runnin a known true case all the way in, rotating the expander rod half a turn or so and re-locking. Lock nuts often tend to cock things. Lot of times if you fiddle with all the variables, you will find a sweet spot. Always a bummer when one tries their best and manages to make good things worse when the object was to make good better. Sam

November 7, 2001, 05:53 PM	#3
bk40 Senior Member Join Date: January 12, 1999 Location: Mississippi Posts: 1,004	Place an o-ring between the press threads and bottom of your FL die. The o-ring lets your die float itself as concentrically as possible. Without going to custom dies, you can use the Redding die that sizes necks with a bushing rather than an expander button.

November 9, 2001, 11:26 AM	#8
Bogie Senior Member Join Date: June 5, 2000 Location: Job hunting on the road... Posts: 3,827	Disclaimer: I shoot benchrest Gitcherself a Redding, or other, die that uses a sizing bushing. Your brass won't stretch as much either. Assuming a factory chamber, you're not going to get a great deal out of neck turning. I use Lee collet dies on my varmint rifles. They work very nicely. I seat the bullets with Wilson (or for my 6PPC, a Carstensen) in line seaters. If you don't want to do that, just go buy the Redding. __________________ Job hunting, but helping a friend out at www.vikingmachineusa.com - and learning the finer aspects of becoming a precision machinist. And making the world's greatest bottle openers!