Using a Case Gauge

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hmr-hound

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Hi Folks

I am beginning reloading for my wk180. I have sized some brass, when i insert into my Lyman case gauge the case head is just below or at the lower tolerance.

Do I need to start over with new brass or will this be acceptable for use in an AR?

I've check many different factory ammo types, some are within, some are not.

Thank you
 
I've found my Lyman case gauges to be a good 'reference' point but ultimately the rifle you're intending to use the rounds in is the deciding factor. (Both my 308's can handle slightly proud of case gauge max without a hiccup whereas my 300aac's seem to need within case gauge to cycle consistently.)
If they're smaller (deeper if I'm reading your post correctly) than the case gauge, not too hot a load for the rifle or brass to handle they should work fine in your AR if you're not trying to get down to the sub 1/2 moa territory.
Continuing to size them as much will be working your brass more than necessary and decrease lifespan.
 
The problem with many drop in case gauges is you can not measure a fired unsized cases because of their fired diameter.
Meaning finding out the shoulder location of a fired case and then set the die up for the proper amount of shoulder bump.

Below a fired Lake City 7.62 in my JP Enterprise gauge that is at minimum SAAMI case dimensions. And the fired case body diameter will not let the case fully drop into the gauge.

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Below the same case above in a Dillon .308 case gauge that is slightly larger in inside diameter. And you still do not know the cases fired shoulder location because the case shoulder is not resting on the gauges shoulder.

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And with a semi-auto the resized case diameter should be .003 to .005 smaller than its fired diameter. This allows the case to spring back from the chamber walls and extract reliably.

Below with the Hornady cartridge case headspace gauge you can measure a fired case shoulder location without interference.
The case below was fired in my AR15 and after measuring its fired length I set the die for .003 shoulder bump.

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Bottom line, if you want to continue to use your case gauge the resized cases should fall between the marks on the gauge. You can also drop some factory loaded ammunition in the case gauge to get a idea on factory shoulder location. You can fire the cases you have that fall below the minimum length but you should check these case with a bent paper clip for thinning.

NOTE, I buy bulk military Lake City cases because they are made of harder and thicker brass in their base. This allows the fired cases to withstand the stresses of being fired in longer military headspaced firearms.

Below the amount of the shoulder bump during sizing will be your head clearance when the loaded round is chambered. The ball park figures for shoulder bump is .001 to .002 for a bolt action and .003 to .006 for a semi-auto. And excessive head clearance will allow the cases to stretch excessively to contact the bolt face when fired. And the excessive head clearance will cause case head separations.

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Below rather than use a bent paper clip because I collected .303 British Enfirld rifles I used the RCBS Case Mastering gauge. This gauge allowed me to measure case stretching and thinning in thousandths of an inch.

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The factory loaded Winchester .303 case below stretched .009 on its first firing. And the same batch of cases failed and started to separate on their third firing when full length resized.
And excessive head clearance caused the cases to to stretch and fail.

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Below the more head clearance your cases have the further they need to stretch to meet the bolt face.

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Awesome, thank you very much guys. I think I'll load my brass with a tuned down plinker load, then keep the case between the lines next time around. I ordered some Frontier ammo to get some fresh Lake City brass too.
 
bigedp51, I always appreciate the time and effort you put into your replies here. I dont comment much but I have learned some from the well illustrated examples you post.
 
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You also have many Canadians in this forum that know far more than I do about firearms and reloading.

I learned a long time ago in the military that images are imprinted in your brain and retained far longer than the written word.

And the images and photos I post save my two dyslexic typing fingers from being overworked and spell checker from becoming utterly confused.

This is a great forum and I will never forget the help I received here after getting my first .303 British Enfield rifle.

And remember sometimes a drop in case gauge is totally worthless. And why a Hornady cartridge case headspace gauge is better because it measures from the base of the case to its shoulder.

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Below a brand new unfired Remington .303 British case in a case gauge showing how short the case shoulder location can be.

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And below a fired .303 British case that is resting on its shoulder in the gauge. The amount the case is sticking above the gauge is how much longer the military Enfield chambers are vs American SAAMI standards. And why full length resizing the .303 British shortens case life and causes case head separations.

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OP do you have a Hornady Lock N' Load headspace gauge? If not, tune your caliper to 0.330 lock it, use a perm marker to color the shoulder of a case then use your caliper to draw a line around shoulder where it touches the 0.330 thickness . Measure the distance between the bottom up to that line (do it a few times around the brass and take the average) using your caliber and that should give you your current case's headspace. For American Eagle .223 55gr (black box 20rds) factory I see the measurement is around 1.454 to 1.455. I don't have other brand so I cannot compare to other 223 ammo just now. Not a single one (picked from random selection from a box of 1000 rds case) measures up to the 1.459 or 1.460 I see most Youtube vids mentioned. So I guess factory will load them shorter as most of the time people said beware of over max of 1.4666. I rarely hear below min but from the comments above I can totally see case-head separation can happen.

I am also new to reloading and I choose 223 to start since it seems to be most easy for me to start. My first batch of .223 fired cases full length resized with the Lee dies ended up with 1.452(5) to 1.455 (majority around 1.453 to 1.454). I found the 1.4525 are barely touches the min of the Lyman case gauge. From touch and visual they are still at the min line I guess...

I also wondering if I am on the right track or my die setup needs to tune up for slightly longer? I will take some pic tonight so may be we can share data. These are once fired brass so I hope if mine are a bit on the shorter side they are still ok with a -10% load. Still waiting for my primer and powder so I won't be able to really get something loaded before mid Feb.

As I said I am new. So if you see anything wrong is what I said please feel free to correct me ;)
 
hmr-hound said:
Seeing how deep a brand new casing is sitting makes me feel much more comfortable with my brass. Mine aren't nearly that bad
Click to expand...

I have had new Winchester .243 cases .009 shorter than my GO gauge making the cases .010 to .011 shorter than the chamber. So the case being a smidgen below the minimum setting on the case gauge is not the end of the world.

Below most rifle calibers have .010 between minimum and maximum headspace. But a new rifle is setup with a GO and NO-GO with approximately .003 between the two gauges.

Below from the Pacific tool and gauge website.

Pacific Tool and Gauge offers three lengths of headspace gauges per rifle caliber. In order from the shortest to longest, they are: GO, NO-GO, and FIELD:

1. GO: Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gauge, the chamber will accept ammunition that is made to SAAMI’s maximum specifications. The GO gauge is essential for checking a newly-reamed chamber in order to ensure a tight, accurate and safe chamber that will accept SAAMI maximum ammo. Although the GO gauge is necessary for a gunsmith or armorer, it usually has fewer applications for the collector or surplus firearms purchaser.

2. NO-GO: Corresponds to the maximum headspace Forster recommends for gunsmiths chambering new, bolt action rifles. This is NOT a SAAMI-maximum measurement. If a rifle closes on a NO-GO gauge, it may still be within SAAMI specifications or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gauge. The NO-GO gauge is a valuable tool for checking a newly-reamed chamber in order to ensure a tight and accurate chamber.

3. FIELD: Corresponds to the longest safe headspace. If a rifle closes on a FIELD gauge, its chamber is dangerously close to, or longer than, SAAMI’s specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been inspected and repaired by a competent gunsmith. FIELD gauges are slightly shorter than the SAAMI maximum in order to give a small safety margin.

NOTE, a military .303 British Enfield rifle at maximum military headspace and with a cartridge rim thickness of .058 can have .016 head clearance.
 
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