Best method to measure headspace?

[megastink]

I've run into a few issues using my LE Wilson case gauges. With my 243 and 6.5 Swede, the cases fit into the gauge, but the bolt is slightly heavy to close. I had used once fired brass that were used in each rifle and full length sized each one, then trimmed, so I was confused on the issue. I had relied exclusively on the Wilson to measure my shoulder bump. I'm not sure if the slight pressure required to close the bolt is an issue, but I digress.

I want to get it right the first time. I am starting to load for my 7 rem mag. I bought some new Norma brass, and this time, I chambered it in my rifle and the bolt closes as it should. Should I just prime and charge? Should I neck size? I cant imagine that a FL resize is warranted.

Any help on the the bolt close issue and/or advice on new brass prep is appreciated. Thank you!

 

[Dmagna]

I FL size Everytime, I measure to with a headspace comparator to a .001-.003 bump depending on application. .001 on target, .002 hunting .003 on a gas gun.

 

[Dmagna]

Cases should have slight feel on bolt close if you are sizing correctly

 

[cajun]

Those case gauges are kind of a go no go thing. Get a hornady headspace comparator so you can actually measure how much you are resizing. Otherwise just keep screwing the die in until the cases chamber properly.
New brass does not need to be sized. They chamber easily because they are usually under sized and after a couple firings will expand to fit your chamber. With the hornady tool you can actaully measure new brass and fired brass and see how much expansion you get. If the necks are dented or not straight on the new brass you can back the die out to not size the shoulder and run the expander just in the neck to straighten them.

 

[Doom2]

It's possible that you have no issue with headspace. The ejector is spring loaded causes the case to cant in the chamber so there is some resistance naturally. To know for sure you need to remove the ejector to check for sure.

 

[megastink]

It's possible that you have no issue with headspace. The ejector is spring loaded causes the case to cant in the chamber so there is some resistance naturally. To know for sure you need to remove the ejector to check for sure.

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

 

[scott0303]

Whidden case gauge works good also

 

[cajun]

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

You should not have to remove your ejector to size your brass. This is why I like using a comparator where you can get an accurate number and set your die off that. There will be some slight resistance depending on your action. When you chamber the new brass that you know is short. That is what it should feel like. Also I just saw where you are working with a 7 mag. It is very important to minimally resize belted mag cases or the brass will not last long.

 

[QuietTexan]

I've run into a few issues using my LE Wilson case gauges. With my 243 and 6.5 Swede, the cases fit into the gauge, but the bolt is slightly heavy to close.

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:

243 WIN Ammunition Gauge

Choose between SLOTTED or NON-SLOTTED. AMMUNITION GAUGES are uniquely designed to check loaded ammunition, giving you the ability to check your factory ammunition or reloads against a spec chamber. The gauge is machined to the SAAMI minimum chamber spec for the 243 WIN caliber. This…

sheridanengineering.com

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.

.200 Line Measuring Tool Kit

The highest quality, most innovative reloading tools and shooting supplies for precision riflemen. Unparalleled customer service. Shop Now - PMA Tool

www.pmatool.com

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

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:

SINCLAIR INTERNATIONAL REMINGTON 700 BOLT MAINTENANCE TOOL KIT | Brownells

Check out the SINCLAIR INTERNATIONAL available Online at Brownells Today and many more Rifle Tools products are available in our Tools & Cleaning Department.

www.brownells.com

 

[MagnumManiac]

Ok, I have gone through this. In all of my gadgets, comparators and such, the most accurate measuring tool for headspace you can buy is the RCBS Precision Micrometer. I made my own gauge based on a mic you use for measuring cylinder walls, but has the exact dimension for headspace measurement, say .375" for '06 cases and .420" for belted mags. The Precision Mic is just as accurate as my own tool, so I trust it to give me EXACT measurements. I also made a chamber end gauge, which measure clearance to the end of the chamber past the neck.
A comparator is not accurate, neither are case gauges.

Cheers.

 

[Lionel Boyd Johnson]

I must respectfully disagree with MagnumMania regarding the RCBS Precision Mic. Even the readings on the same case will vary depending on how you screw it together on the brass. In addition, the headspace length markings appear not to be related to SAAMI specifications. I've been reloading rifle and pistol cartridges for over 60 years, focused on accuracy for long range and across the course rifle competition as well as hunting. The Hornady headspace comparator used with a good quality dial caliper will tell you what you need to know. Regarding the discussion of removing the spring loaded ejector (if your bolt has one) leaves out the issue of the feel of the firing pin and spring assembly - it should definitely be removed before testing for proper head space.

 

[quandary]

You need to use the LE Wilson case gage depth micrometer in conjunction with the case gage. It works great.

Case Gage Depth Micrometer-CG-MIC

 

[BrentM]

Just get a Good set of calipers and a comparator gauge set from Hornady or others. It is designed to measure from the case base to the middle of the shoulder. The set comes with different heads for different cases and a chart to show which you need. For example I use the .420 diameter gauge on a 6.5 PRC case. Now, for me the key is a good set of calipers. I use Mitutoyo now after going through an absolute pile of cheaper crap. I literally have a draw full of harbor freight level china crap.

 

[xsn10s]

Like the others said get a good set of dial calipers and the comparator set. You can also use a black marker and complete color the case and chamber it. When chambering support the case so it doesn't scrape the ramp or anything else while inserting and extracting. The idea is to see what is contacting when it's fully chambered.