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[Bart B]

The vast majority of my dies are older RCBS dies from the 1970s and 1980s and you can not raise the expander enough to duplicate the Forster design.

On a whim last year I decided to buy a Forster full length 30-06 die and was extremely impressed with the low neck runout readings right out of the die. With the existing RCBS expander assemblies I experimented raising the expanders and using rubber o-rings and did not get the low runout figures I did with the Forster expanders.

Therefore I do not share your results and wonder what type/make dies you are using that duplicate the Forster design.

I used standard RCBS full length dies that I put more threads on the stem so it would be higher in the sizing die chamber. Or use a stem from a shorter cartridge's die. Should have mentioned that.

The problem with your statement is you must turn the case necks to a uniform thickness and if you do not you are just pushing any neck defects to the inside of the case neck. And this is "WHY" bushing dies come with a expander for the people who do "NOT" neck turn.

I disagree. The expander's included for those who want to use them; nothing's mandated by Redding about turning necks first.

Sierra's ballistic tech whose job was to test their stuff for accuracy told me to hone my FL dies out and toss the expander ball. He never prepped cases in any way sizing them with such dies and got 1/4 MOA accuracy with their best match bullets. As far as I know, Sierra now uses unprepped cases full length sized in Redding full bushing dies without expander balls for cases they're made for. I doubt anyone shoots their stuff at 200 yards as accurate as they do.

I tried neck turning to get them uniform but gave up as it didn't make any difference. A .0015" spread in wall thickness will make case mouths and throats a little bit egg shaped when they come out of a gelded die, both outside and inside measurements. But I seat round bullets in them; that makes the case mouth and throat round, too. Don't care if the outside surface has a small spread in its dimension to the bullet; that doesn't touch anything when the round's fired. Accuracy is excellent or better.

 

[Barrelnut]

The problem with your statement is you must turn the case necks to a uniform thickness and if you do not you are just pushing any neck defects to the inside of the case neck. And this is "WHY" bushing dies come with a expander for the people who do "NOT" neck turn.

Lot of good info getting kicked around in this thread.


Bigedp51,

I follow what you have been saying. I understand the neck thickness thing. But got to thinking, so I have a question on the quote above.

Assuming you've got some fairly high grade and consistent brass, wouldn't the variance just get pushed back to the the " outside" of the neck when the bullet was seated? Thanks.

 

[ohiohunter]

No, the variation would end up applying unequal force to the bullet creating drag at the points of higher tension ultimately the bullet will not engage the lands equally. You want equal tension throughout your neck to release at the same pressure engaging the rifling as square as possible.

So if half your neck has .002" tension relative to the center while the other half has .005" tension the bullet will still be seated into the neck, but the higher tension will send the bullet off of its intended path due to the increased drag. The bullet will not equalize the different tensions. Hence why a neck w/ 0.01" tension will be higher pressure than a neck w/ 0.001" neck tension.

 

[bigedp51]

Lot of good info getting kicked around in this thread.


Bigedp51,

I follow what you have been saying. I understand the neck thickness thing. But got to thinking, so I have a question on the quote above.

Assuming you've got some fairly high grade and consistent brass, wouldn't the variance just get pushed back to the the " outside" of the neck when the bullet was seated? Thanks.

Why force a bullet into a case neck to iron out any irregularities when a expander of any type will smooth out the inside of the neck. Many competitive shooters when either neck sizing or full length sizing use a expander die instead of the regular expander in the die to expand the neck and reduce neck runout. "BUT" this is a two step process and the Forster die is one step sizing and expanding and with uniform neck thickness produces below .001 neck runout.

Too many people think a standard full length die will pull the neck off center and cause problems and induce runout. And the Forster die will make the necks very straight with the lowest runout of any die I have.

Expander Mandrels and Neck Tension

"Lapua brass is so good that you'll be tempted to just load and shoot, if you have a "no-turn" chamber. However, some minimal case prep will ensure more uniform neck tension. This will produce better accuracy, more consistent bullet seating, and lower Extreme Spread and Standard Deviation (ES/SD). Lapua brass, particularly 6BR, 6.5×47, .243 Win and .308 Win comes from the factory with tighter-than-optimal necks. Before you seat bullets, at a minimum, you should inside chamfer the case mouths, after running an expander mandrel down the necks. The expander mandrels from both Sinclair Int'l and K&M will both leave the necks with enough neck tension (more than .001″) so you can then seat bullets without another operation. Put a bit of lube on the mandrel before running it down the necks — but remove any lube that gets inside the necks before seating bullets."
http://www.accurateshooter.com/technical-articles/reloading/expander-mandrels-and-neck-tension/

 

[Barrelnut]

Thanks guys,

I use Redding bushing dies. With the expander ball, I can get up to .003 - .004 thought of run out. Without the ball, runout is .001 or less. Looks like Sinclair is gonna get more of my money this week...

 

[ShootnMathews]

I think some of you may be overthinking this a little. Maybe if you were trying to set a world record or something some of the suggestions may help a little. But if his brass is annealed so that the die can size it easily with minimal spring back and he's getting enough run out that the gun will not group well. The die probably needs sent back as defective.

I personally prefer FL bushing dies because it saves a lot of work hardening and I have never had any problems getting the gun to shoot to 1/2 MOA hunting standards even with poor brass. I use pretty much only lapua and can usually get a quality gun to shoot 1/4 MOA WITHOUT having to turn the necks.

Now like I said if you're trying to wring out the accuracy the little stuff makes a difference, but if he's getting so much runout to degrade accuracy that bad, something is not machined right in the die in my opinion. Either the neck portion or the expander ball. Who knows. I'd send it back.

 

[4xforfun]

I'm not posting this to bust your chops 4xforfun "

The problem with your statement is you must turn the case necks to a uniform thickness and if you do not you are just pushing any neck defects to the inside of the case neck. And this is "WHY" bushing dies come with a expander for the people who do "NOT" neck turn.


[/U][/U][/U]Alternative to Bushings — Honed Full-Length dies
Conventional, non-bushing full-length sizing dies can create ultra-accurate ammo with very low run-out.

Exactly, and if you use the expander mandrel (for your purpose) all YOU are doing is pushing the defects to the OUTSIDE of the case neck. What is difference.....defect on the outside or the inside? If the case is defective, the case is defective, and NO method short of neck turning or culling the bad brass is going to fix it.

 

[jmd025]

i was doing some tinkering making myself some notes and now im reading this thread.... my notes i jotted down may not be 100% pertinent, but they will fit in the general theme of this thread maybe so heres some measurements i just took.


Once fired brass neck dimension : 0.287"
Loaded round..............................: 0.283"
Forster FL sizer w/o expander.....: 0.278"
Forster FL sizer with expander....: 0.280"

to me, i dont care for whats going on while seating , when the die was used without the expander. It will be honed to change this.

 

[ohiohunter]

Are those out side diameter numbers for a 270 w/ forster benchrest dies?

 

[jmd025]

Are those out side diameter numbers for a 270 w/ forster benchrest dies?

257 WBY Forster BR FL


270s measure in the .300-.302 range sized and loaded

 

[ohiohunter]

257 WBY Forster BR FL


270s measure in the .300-.302 range sized and loaded

After I hit submit I was thinking either you turn your necks paper thin or its a 25.

How much will you have honed out? I'm thinking if you use the ball how much contact do you want it as it comes through? 0.001"? Is that enough to do its job yet little enough to lessen run out?

My competition dies are thankfully forsters, but I have a few reading type s bushing dies and I'm debating on removing the ball.

 

[jmd025]

After I hit submit I was thinking either you turn your necks paper thin or its a 25.

How much will you have honed out? I'm thinking if you use the ball how much contact do you want it as it comes through? 0.001"? Is that enough to do its job yet little enough to lessen run out?

My competition dies are thankfully forsters, but I have a few reading type s bushing dies and I'm debating on removing the ball.

Still debating how i will approach it. I have a Redding Type S for this caliber too that im going to run several bushing sizes with and without the expander to try to really nail down a hone size and how i plan to proceed. Not perfect testing but will educate me enough for a guess.

Springback is a mother... gotta figure that part out.

I can tell you on a quick try i made with the Type S and a 0.282 bushing, with NO expander installed, the brass came out in the lower 0.27Xs ( i dont remember the number and didnt write it down, but i do remember thinking , "nah, i dont like that") I need to repeat this and make sure i wasnt trippin' on acid that day.

ultimately im looking for a .001-.002 interference for bullet seating

 

[rcoody]

Still debating how i will approach it. I have a Redding Type S for this caliber too that im going to run several bushing sizes with and without the expander to try to really nail down a hone size and how i plan to proceed. Not perfect testing but will educate me enough for a guess.

Springback is a mother... gotta figure that part out.

I can tell you on a quick try i made with the Type S and a 0.282 bushing, with NO expander installed, the brass came out in the lower 0.27Xs ( i dont remember the number and didnt write it down, but i do remember thinking , "nah, i dont like that") I need to repeat this and make sure i wasnt trippin' on acid that day.

ultimately im looking for a .001-.002 interference for bullet seating

neck springback?

hard to get consistent neck tension as that brass work hardens

when I started annealing I had an enlightening experience.

Now all of my reloading brass is Lapua. I had about 200 rounds of brass with well over 10 firings on it. Now the cases were still good. Tight primer pockets and no cracked necks. Well I had culled out the ones with loose primer pockets and cracked necks. I learned to back off for better accuracy and longer brass life.

anyway this brass was in the back of the reloading cabinet. I had already replaced it with new brass but one day when I had my annealler set up I decided to run it too! Playing with the annealler as much as wanting to use the brass.

Well anyway I annealed it, ran it through the ultrasonic, sized it and loaded it. You know how it feels to seat a bullet in new Lapua brass. Well that old brass was like new again. At that point I realized just how important annealing is to not only extend the life of the brass but to keep it consistent too!

 

[jmd025]

fully agree with annealing. I was using once fired brass so i assume workhardening to be a non issue with it.

neck springback?

hard to get consistent neck tension as that brass work hardens

when I started annealing I had an enlightening experience.

Now all of my reloading brass is Lapua. I had about 200 rounds of brass with well over 10 firings on it. Now the cases were still good. Tight primer pockets and no cracked necks. Well I had culled out the ones with loose primer pockets and cracked necks. I learned to back off for better accuracy and longer brass life.

anyway this brass was in the back of the reloading cabinet. I had already replaced it with new brass but one day when I had my annealler set up I decided to run it too! Playing with the annealler as much as wanting to use the brass.

Well anyway I annealed it, ran it through the ultrasonic, sized it and loaded it. You know how it feels to seat a bullet in new Lapua brass. Well that old brass was like new again. At that point I realized just how important annealing is to not only extend the life of the brass but to keep it consistent too!