Understanding headspace and shoulder sizing


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MovedWest
November 17, 2012, 06:03 PM
I've been loading for handgun for years, but just recently acquired the equipment and materials to load for 6.5x55 Swede. I've looked through several of my reloading books, but can't find info on how to properly gauge headspace and shoulder sizing without using drop-in gauges. And I can't find drop-in gauges for this caliber either! :(

Can someone give me a push? I'm kinda stuck and don't want to guess when it comes to these parameters.

I DO have a Forster No-Go chamber gauge that I picked because I mistook it for something for reloading, but it seems to be more of a gunsmithing tool.

Help! :banghead:

-MW

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Walkalong
November 17, 2012, 06:37 PM
shoulder sizing without using drop-in gauges.

Get something to measure where the shoulder is and bump the shoulder back .003.

http://www.thehighroad.org/showthread.php?t=504759

Or remove the firing pin assembly from your bolt. Start sizing the brass a little at a time until it chambers with very light resistance. A hair more and your there.

gamestalker
November 17, 2012, 06:55 PM
If all you have is a FL die, begin simply by adjusting the FL die down just enough to resize just the neck, and not shoulder. I would start off with the shell holder just barely clearing the die at full stroke without a case yet. Then assuming your brass will chamber and hasn't been fire formed, just run it through the die and begin loading them. Once your brass has reached the point where it won't chamber, or does so with considerable resistence, begin adjusting the FL die down in very small increments of .003" or less, or until the brass will chamber with very light resistence.

I've done it this way for many years. But as for using a gauge, I have never found it absolutely necessary for setting head space. It really isn't difficult to know when you have reached the right adjustment using the FL die, the brass to chamber fit if adjusting in very small increments, will be obvious when you've found the correct shoulder placement, or head space.

GS

ranger335v
November 17, 2012, 06:55 PM
A drop in gage is no more helpful than your chamber. Get a comparitor/"headspace" and seating gage instead; Sinclair, Hornady, Innovative Technologies or RCBS Precision Case Mic.

For a bolt rifle there's no point in setting shoulders back further than the fired length of your longest cases, the fired case shoulders have already expanded and shrunk back a thou or two anyway.

Taurus 617 CCW
November 17, 2012, 07:45 PM
Not sure if this is what you are looking for but it's worth a look.

http://www.grafs.com/retail/catalog/product/productId/9753

GLOOB
November 18, 2012, 01:49 PM
Gamestalker nailed it. Neck size, only, until the cases no longer chamber. Then bump them back a little at a time, till they do. Lock your die down.

By measuring the gap at the top of the ram stroke with a case in, you will see how much extra headspace you have in your rifle.

Unless you have a rifle known to have excessive headspace, like some milsurp rifles, or if your brass is separating prematurely, you probably have barely any, like most SAAMI spec chambers. An excessively large headspace on a modern rifle is a manufacturing defect or improper assembly.

I'm kinda stuck and don't want to guess when it comes to these parameters.
Every non reloader who fires a gun without having it inspected by a smith is taking a guess that the manufacturer made the gun, correctly. I don't get why you'd look for a problem where there probably isn't one. Remember, partial FLR is OPTIONAL. Plenty of people FLR rifle cases. So you can't get partial FLR wrong, unless the cases don't chamber. Which is pretty obvious.

MovedWest
November 19, 2012, 01:01 AM
Thanks everyone for the replies. I know I'm probably over thinking it, but I don't want to guess that I'm doing the right thing. Part of it is me being way obsessive-compulsive, the other part is me not wanting to create a dangerous situation.

It sounds like FLS is a safe bet and I did that to work up my first 20 rounds tonight. I'm going to play around with neck sizing and FLS on those 20 cases after they see a bit more use and see how that pans out.

Thanks again!

-MW

ShadowsEye
November 19, 2012, 01:28 AM
If all you have is a FL die, begin simply by adjusting the FL die down just enough to resize just the neck, and not shoulder.

Reloading noob here, but how exactly is this possible? The neck sizing portion is at the top of the die, isn't it impossible to size the neck without running the case all the way into the die? Isn't that why neck sizing dies exist?

cfullgraf
November 19, 2012, 07:48 AM
Reloading noob here, but how exactly is this possible? The neck sizing portion is at the top of the die, isn't it impossible to size the neck without running the case all the way into the die? Isn't that why neck sizing dies exist?

Neck sizing dies only resize the neck. they are cut generously in the body area so that the body is not resized.

Some folks back off a full length sizing die to minimize the sizing they get. Some, or most of the neck, is sized, the shoulder is not set back, and only part, or none, of the body is sized.

In theory, when a full length sizing die is set to contact the shell holder, the case is sized to minimum SAAMI dimensions.

This is the basics and the science of case resizing goes on farther.

Walkalong
November 19, 2012, 09:47 AM
By the time you get a FL sizer down far enough to size enough of the neck, it will size the body a little as well. When the body is being sized, the shoulder tends to get pushed forward a little right before and until the inner "shoulder" of the die contacts the brass shoulder and starts moving it. The tighter the sizer the more this can happen.

918v
November 19, 2012, 11:18 AM
True dat.

beatledog7
November 19, 2012, 01:30 PM
For brass acquired from somewhere else, or for any brass that's to be loaded for a semi-auto, FL size as described above. If I fired the round in my own bolt gun, I neck size it and repeat with subsequent firings until it is hard to chamber, then FL size as described above.

Never neck size for a semi-auto, as the gradually lengthening case increases slam fire risk.

W.E.G.
November 19, 2012, 01:37 PM
Simple version:

1. Buy box of factory ammo.
2. Buy RCBS Precision Mic tool.
3. Use tool to measure size of factory ammo.
4. Use your sizing die to push shoulder of case back so that it measures same as factory ammo.

James2
November 19, 2012, 04:36 PM
If you want simple, just full length size your brass, and stop worrying about it.

Brass is full length sized in a full length sizing die when the shell holder touches the die when full up with a brass in place.

If you are only loading brass that has been fired in your rifle, you can back the die out until you get about .010 between the die and shell holder when fully up. This will size the neck, but not bump the shoulder. It is wise to always try these in the rifle to see if they are going to chamber OK, before loading them.

The other option is to get a neck sizing die. I would only use one of these if the brass was fired in my rifle. If it is mixed brass from other rifles, I suggest the full length sizing die, set to full length size them.

The problem is that rifles vary a bit in the location of the shoulder and overall size. If the casing is not sized enough to fit your rifle, the bolt will be hard to close. Hence the recommendation to try them in your rifle after sizing and before loading, if you are not full length sizing.

ranger335v
November 19, 2012, 06:48 PM
Only chambers have "headspace", cases have length to shoulder.

Bottle neck chambers have a lenght tolerance of something like zero to plus 7 thou. Cases have a tolerance range of zero (which is a thou or two smaller than the chamber) to minus about 7 thou. Thus the tightest SAAMI ammo fit will still chamber easily no matter the ammo.

If we have a minimum chamber and a maximum sizer die our cases will still fit quite well. If our chamber is max and a minumum sizer the total space at the shoulder can easily be some 14-16 thouanths. a bit sloppy. That's safe but it's a bit too much open space for extended case life before head seperations occur. Most fits are closer than that simply due to normal variation in each combonation.

Drop in case gages simply tell us if our ammo will fit into any standard chamber ever made. Most handloaders prefer to size for best fit and that's where the various case shoulder gages get really handy for adjusting our sizers.

Walkalong
November 19, 2012, 09:43 PM
Yep, and there are plenty of cheap ways to measure where the shoulder is. Naturally there are plenty of pricey ones as well.

http://www.thehighroad.org/showthread.php?p=6270171#post6270171


.300 Blackout.

http://www.thehighroad.org/attachment.php?attachmentid=167074&stc=1&d=1340796258

Walkalong
November 19, 2012, 09:49 PM
More stuff on headspace.

http://www.thehighroad.org/showthread.php?t=617421

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