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Old January 5, 2013, 11:49 PM   #1
TheDutchman19
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Neck sizing bushings?

Hello

Next week I pick up a new 308 that I want to start loading for. I am going to get Redding Type S dies and have not bought bushing die before. The new dies do not come with them. Is there a "neutral" size bushing for 308 or how do I know which one(s) to buy?
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Old January 6, 2013, 10:13 AM   #2
Roy Allain
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Redding Type S Bushing Dies

Is this a custom rifle? Or a factory rifle?

I a factory rifle, you need do nothing. Any cartridge will fit.

If a custom, do the following:

If you can, load one (1) empty unprimed brass with the bullet of your choice. Then measure the neck OD with a micrometer. The demension is what your basic cartridge will be when you insert it into the chamber.

Again, if a custom chamber, what is the chamber neck demension? Subtract .003 from that measurement. That is what your loaded round MUST measure to chamber properly and also release after firing.

There is much more, but we'll take one step at a time.

Roy
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Old January 6, 2013, 11:01 AM   #3
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As Roy indicated you need a few fired cases from you rifle. Use the same brand of brass. You measure the OD of the case necks and subtract 0.003 inches. That gives you a starting point. You then have to change the bushing diameter to get the correct neck tension. Because each case maker uses a different thickness brass you will need a different bushing for each brand of brass (case).
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Old January 6, 2013, 12:10 PM   #4
reynolds357
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I use bushing dies for benchrest only. Unfortunately 99% of the time I either have to end up inside turning or outside turning the necks. I have 6 different bushings for my 6.5X284 thousand yard gun and I still have to turn.
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Old January 6, 2013, 10:03 PM   #5
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You should get a set of bushings for the die to cover a range of neck wall thickness for different makes of brass as well as sizing the necks in steps. I determine bushing size by measuring the neck wall thickness, adding the diameter of the bullet then subtracting the desired neck tension. When sizing with a bushing it is best not to reduce the diameter of the neck by more than .005 at a time otherwise it may increase neck runout. When neck sizing I typically do not use the expander.
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Old January 7, 2013, 12:45 AM   #6
TheDutchman19
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Is there a tool or gauge that helps you fine tune for desired neck tension?
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Old January 7, 2013, 08:30 AM   #7
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Actually Redding has changed their guidance. They used to suggest subtracting 0.002", now they suggest subtracting 0.001". Their current guidance can be found here.

You will need more than one. What works best for you also depends if you intend to use the expander or not. If you use the expander, selection has more latitude. If you don't expand, you need to use the correct expander for your brass. If you convert to a carbide expander button, it will significantly reduce the effort to expand the neck, and reduce the risk of pulling the neck off center.
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Old January 7, 2013, 08:59 AM   #8
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Note that the case neck brass hardness will also determine how much spring back it has from being sized down. Over the years of using gelded full length sizing dies (no balls), the die's (bushing's?) neck diameter should be whatever lets the bullets stay in place when in the rifle's box magazine and the round in the chamber's fired. If the ammo's going to be single loaded, then less neck tension is fine. Depending on the case neck wall thickness and the brass, it is 1 or 2 thousandths smaller. You'll have to pick the bushing size that best suits your objectives.
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Old January 7, 2013, 07:29 PM   #9
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There is no formal tool for measuring neck tension. You can use the push method to see how far back the bullet sets when you push it on the table.
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Old January 7, 2013, 08:13 PM   #10
reynolds357
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I usually use almost no neck tension. I push the bullets to the lands very softly. On most of my non hunting rifles seat depth is not very critical because I use the old school method of very little neck tension and let the lands push the bullet back into the case.
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Old January 7, 2013, 09:23 PM   #11
tobnpr
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Quote:
Note that the case neck brass hardness will also determine how much spring back it has from being sized down.
Won't this depend on whether or not it is annealed, (and how recently), as well as how many reloads the brass has had, and it's quality (e.g. Lapua or Win).

If one thou works now, might not two thou be the "right" number down the road? Just sounds like it's a variable, that's going to be continually changing.

So how to decide what's optimal?

No device I'm aware of to measure neck tension (pullout), is there?
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Old January 7, 2013, 10:22 PM   #12
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tobnpr, yes, how much case necks are annealed is critical. But I don't think the number of rounds a case has been fired makes much difference. Not after a friend shot the same .308 Win. case 57 times putting Sierra 168's into 3/10ths MOA at 100 yards. Full length sized every time, too, then he ran out of test powder. Max loads, too, not reduced charges.

The optimal amount of neck tension's what gives the lowest muzzle velocity spread. Best way I know of to do that is to have case neck tension as small as possible so bullets don't get displaced in normal handling. Seat them long enough so they're set back several thousandths (10 to 15's good) by the rifling when the bolt's closed on them. That way, as the leade erodes away from firing, all bullets fired in one session will meet the same resistance starting into the rifling.

PA-joe and tobnpr, there are formal tools to measure neck tension. Military ammo specs call for a release force range or minimum. For example, 7.62 NATO M80 ammo has a spec of at least 60 pounds of force to get the bullet out. M118 and M852 match ammo's spec'd to at least 40 pounds.

One can easily make their own test setup. Put a collet type bullet puller in a board clamped to a benchtop, then wire a bucket onto a shell holder that slips onto the rim of a round with its bullet held by the collet. Start dumping stuff into the bucket until the bullet comes out; Heavy bullets are great if you've got several pounds of 'em. Weigh the bucket and its contents. Write down the weight in pounds. Most folks who've done this are agast at the range of weights needed to get their bullets out of a case. Also the average weight to do so. Especially when compared to factory and military ammo.
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Last edited by Bart B.; January 7, 2013 at 10:31 PM.
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Old January 7, 2013, 11:14 PM   #13
reynolds357
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Bart, I learned something new. I am going to have to rig me up one of those testers.
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Old January 8, 2013, 09:11 AM   #14
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What are the pros and cons of using the expander ball?
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Old January 8, 2013, 09:27 AM   #15
old roper
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They been making tool for year on seating bullets.

When I first start BR I'd put my arbor press on bathroom scale and measure lb

Here some home made ones

http://home.comcast.net/~jesse99/tension.html

Here one for the arbor dies

http://bulletin.accurateshooter.com/...ion-reloading/
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Old January 8, 2013, 01:37 PM   #16
Bart B.
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TheDutchman19 asks about the pros and cons of using the expander ball.

A pro is, dies with them are cheaper, so you've got more money left to spend foolishly on some other fun stuff.

One con is, they bend case necks, especially when their diameter's a lot bigger than the sized down case mouth they gotta be pulled through. Another con is they are typically too small because the one that comes with the sizing die has to be small enough to handle all the possible case neck diameters the reloader's cases have and still make the case mouth hold the bullet very firmly.
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Old January 8, 2013, 06:45 PM   #17
TheDutchman19
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Hey guys

Thanks for all of the input. The further I follow Alice down the rabbit hole, the more questions that come up. The manufactures don't make it easy, because they offer products with every option and price point. Thanks for taking the time.

David
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Old January 8, 2013, 09:09 PM   #18
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Interesting way to rig up something to measure neck tension, and consistency.

Then, to figure out how much is necessary to avoid bullet movement...

Caveat to semi shooters... more is safer...

Somewhat related (not much, but interesting nonetheless), an AR manufacturer recommended cannellured bullets, CRIMPED, for use in the .300 chamberings (Blackout, Whisper) for that platform.

Apparently, not too uncommon for someone to shove a clip of .30 cal into a .223/5.56 rifle...

A heavily crimped round (with a ton of neck tension) is more likely to alert the shooter that his bolt's not closing without the forward assist. A lightly seated bullet will just get shoved into the case, compressing the load and causing quite a "moment" for the shooter, and the rest of the firing line.

No doubt, rough handling of ammo, banging around in the clips, is the reason for the really heavy pullout (or, shove-in) requirements of the military ammo.
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Old January 9, 2013, 08:01 AM   #19
Bart B.
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tobnpr's comment about a lightly seated bullet that will just get shoved into the case, compressing the load and causing quite a "moment" for the shooter, and the rest of the firing line. . . .

Consider the fact that competitive shooters loading ammo for single loading in slow fire matches have been "light seating" bullets for decades. With max loads at normal peak pressures, there's no increase in peak pressure that'll make things unsafe.

Yes, those bullets will be shoved back into the case. But a dozen or two thousandths of bullet setback when chambered is nothing. If that's thought to be a problem, consider the fact that there's no significant peak pressure difference from a new barrel's effect on a given load compared to several thousand rounds later when its leade has lengthened 1/10 inch or more from erosion. Besides, few, if any, safe max loads have 100% loading density anyway, so seating the bullet back a bit when chambered is no big deal.
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Old January 10, 2013, 07:47 PM   #20
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Not arguing your point, but you misinterpreted mine.
I was making the point that the fact the bullet was able to be shoved back in the case- and not be apparent to the shooter due to "light" neck tension- was what would cause the "moment". Meaning trying to send a .30 cal bullet down a .22 cal bore, not the fact that the load was compressed.

My intuition tells me that will always end in a blown apart receiver and/or split barrel.
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Old January 10, 2013, 08:06 PM   #21
Bart B.
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tobnpr, I agree. Shooting a 30 caliber bullet into a 22 caliber bore might be catastrophic.

But I think trying to chamber a .308 Win. round into a .22-.308 wildcat chamber would end when the bolt wouldn't close on the case 'cause it's neck was too big to go into the chamber neck. But I get the idea you're referring to.

People have shot the necks off .30-06 cases as they were bonded to the bullet by electrolosis or something else for some reason. Case necks went into and out the barrel when the round fired. But the fired, neckless case ejected normally and the only comment the shooter made was to the effect that it sounded louder than normal.
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Old January 10, 2013, 08:31 PM   #22
reynolds357
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tobnpr, shooting is not idiot proof. You might possibly could cram a .270Win into a .25-06 if the 270 was loaded at 85% or less case capacity. To load the wrong caliber in the wrong rifle, the bullet dia's would have to be pretty close.

Last edited by reynolds357; January 10, 2013 at 08:39 PM.
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