Best method to measure headspace?

[UncleDano]

One potential issue there is the LE Wilson gauge does NOT measure body diameter. It's cut large to be able to measure headspace using their mic tool, and to check case length, of fired brass.

Eventually body demensions need to be sized also, and dropping into an LE Wilson is no guarantee of chamber fitment at the case head.

Sheridan Engineerings makes true min-spec case gauges to check sized ammo with:

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Hornady Cartridge Gague and Whidden Case Gauge are SAAMI spec minimum, but Whidden checks headpsace off the belt for 7RM. SAC makes the best comparator set available right now IMO to take measurements, Whidden is my second choice.

PMA makes a little printed measuing tool that tries to get a repeatable measurement on th e.200 datum line. it uses calipers so it's not the most precise tool available, but it's good enough to check new/FL sized brass versus fired brass to see how much sizing you're getting at the back end of the case.

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Yes, I use bolt drop on rifles to set maximum headspace usually. It's an easy way that's separate from taking measurements and the risks of tolerance stacking. It either goes or it doesn't, no theoretical at all. I have just about every measuring tool available, and I use them to record data, but the set point of the die is based on the real chamber. Same thing with trim length of the brass.

I normally don't have the ejector installed at all until brass is fully formed and stabilized, I'll also pull the entire ingition group from the bolt to get the drop. Easy enough if you buy a couple of simple tools:

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Good reminder about the LE Wilson to be used on FIRED cases. The LE Wilson has a micrometer measurement attachment, that allows you measure exact headspace and use to set back shoulder the exact amount you choose.

 

[RegionRat]

If I remove the ejector and it closes with normal pressure, then I'm good?

Yes, by definition if the case chambers without drama you are good.

Just to be sure we don't swirl, that is not the same as eliminating every possibility with respect to having too much slack, but it does achieve the goal of reliable feed and a nice close fit. By definition, if you cannot close the bolt without drama, everything else is cold comfort.

In the future, when we go down the rabbit hole and sharpen the pencil on the topic, there is a distinction between establishing headspace versus difficulty with sizing cycled brass or chambering drama.

The biggest distinction is there are lengths like the one we call the shoulder datum, but there are also diameters.

Strictly speaking, headspace is independent of diameter discussions, and diameters can cause as many issues with bolt closure as anything else.

My advice to friends I teach to load rifles... when you dedicate to reloading you should learn the ammo and chamber specs, and own the Go-Gage to be able to set your tools to a more absolute rather than just comparator.

By using the GO-Gage with some tricks like tape to establish the chamber's datum length, you can then learn to measure your brass and set your sizing dies with confidence.

In a shop, we have the gages that increment to the nearest 0.001" that cover the spec range and beyond. But, at home you can learn to use just the Go-Gage to set your tools and check your chamber.

Accumulating tools for topics you know you want to run for the long term, means you should think long term.

Good instruments and go-gages are often not discussed or recommended on forums, and folks should also be encouraged to study the specs for the cartridges they like.

Once you have micrometers, you can learn to check a few critical dimensions on brass and dies. To go to higher level reloading, you learn to coordinate the brass, dies, and chamber to stay out of trouble. Learning to check the shoulder diameter and the 200 line isn't that difficult, but can give you insight when things go wonky. YMMV

ETA: beginners running semi or full auto should also think about owning a minimum chamber gage rather than a plain case gage that only checks the shoulder datum length. A Min Chamber gage is all of the envelope dimensions, not just the shoulder datum length. The Sheriden gage comes to mind since it is available with a cutout that helps teach rookies to debug.

Good Luck.

Happy New Year!

 

[AkleyFan]

I have go/no go gages and will shim them out with layers of tape to find a slight interference fit upon bolt close (usually a stipped bolt) - you could do this with a piece of brass as well. Then I'll use a Sinclair headspace comparator set and/or the RCBS Precision Mic's to find my approximate chamber length. These devices can be used on a piece of brass at any stage of its lifecycle.

There are other methods as well. The "best" method it entirely up to you and what you find suits your needs - safely.

When you FL resize your brass, the shoulder of the case will move forward. Check a fired peice of brass against a FL resized peice of brass and you should see the difference. Set your FL resizer to give you the appropriate amount of headspace as others have advised. Have fun and be safe.