Head Space

[Lefty223]

I can record the measured average number for five cases in order to document barrel wear.

You're talking about cartridge overall length to the ogive ... they're talking headspace to the shoulder.

Good point ... but wrong topic

[Bret]

Watch for shiny rings on your brass, if observed use a feeler to locate a ridge.

Poor man's feeler gauge: Take a paper clip and straighten it out. Sharpen the end to make a wedge. Bend the very end so that the wedge is perpendicular to the bend. Insert it in the case and you can feel rings where the brass has thinned.

[Lefty223]

Insert it in the case and you can feel rings where the brass has thinned.

... usually just above the rim, maybe 1/4" or so ... , but that end of the case, closer to the rim, away from the shoulder.

[markm]

Easiest way to produce in-spec 5.56NATO ammo is to invest $25.00 or so in a good .223/5.56mm case gauge. Set your resizing die to bump the shoulder back until the case rim is just even with the low step on the case gauge. I've found that brass with the shoulder to rim length any longer, even .001"-.002", is not going to function as well as brass that is bumped back to the minimum length for head space. Most factory ammo that I have case gauged also aligns with the low step on the case gauge.

This. No need for other tools, unless you are into gear or obsessed with quantifying every thing.

[LMT/556]

My rounds are towards the upper step of my dillon case gauge but are loaded for a single rifle. Having the Hornady comparator and a separate case gauge just allows double checking against different means, both should agree or make sense when comparing measurements.

[eightmillimeter]

Press cam-over has nothing to do with how much a case gets sized in one press to the next. The only thing it guarantees is full contact between the bottom of the die and the top of the shell holder. It's the only place in the press stroke that is 100% consistent.

When you start measuring your headspace on sized cases eventually you will get to a point where you have that die adjusted just perfectly and every case you size is coming in -.004 but depending on the brass and a few other things you'll get stragglers at -.002 and mysteries at -.005. It's not always spring back. Sometimes the brass is just worked harder and since you have the die screwed back to get that headspace perfect the slop in the ram will give you the variable readings. This is why Redding makes competition shell holders of varying thickness so you can set your headspace AND still cam the press over. Using that setup and fresh or annealed brass you can almost guarantee that every case will come out of the die the same size without springback.

I've been in the game a long damn time and over the years It becomes obvious that reloading for a gas gun is not rocket science and there is no reason to make it so. Any good SAAMI spec dies will work just fine, follow the instructions that come with the set, inspect your cases with a case gauge... You may get one more firing out of a case (maybe) by sizing it to -.003 as opposed to just FL sizing but what did you gain? By the time a 5.56 case has been reloaded 5-6 times you're already way past the designed service life. Just pick a number of times to reload that you are comfortable with and toss em, sleep easy.

[Bret]

This. No need for other tools, unless you are into gear or obsessed with quantifying every thing.

If you want to fine tune your headspace adjustment for loads in each rifle, then you'll need more than just a yes or no gauge. For example, I have an AR180 that has headspace that measures approximately 0.010" greater than most 5.56x45 AR15's. I shoot new factory loaded ammo in it and then resize the cases so that they're only 0.002" to 0.003" less than the AR180's chamber. I can then repeat the process over and over with the brass lasting through numerous loadings. These same cartridges won't fit in most 5.56x45 chambers. If I did resize the brass back so that it would fit in a case gauge each time, then it would stretch much more, wouldn't last as long, and would likely result in less accuracy.

[LMT/556]

What I'm doing also. One size does not fit all and maintain long case life, as demonstrated by rings on my Hornady brass.

[markm]

Unless you're annealing every loading, you'll never get fine tuning on the bump. As pointed out, uneven work hardening leaves you with finding the best average bump. I set my die by checking five pieces in the gauge.

For specific/bolt gun chambers, I size to the chamber fit. Knowing the nominal bump has no value for me.

[bigedp51]

Chambers and dies vary in size and the advantage of the Hornady cartridge case headspace gauge is being able to measure fired cases. Then adjust the die for proper shoulder bump and not push the case shoulder back too far.

Below I'm measuring a fired case from my AR15, I then adjust the die for .003 to .004 shoulder setback using Redding competition shell holders. Each of these competition shell holders allows the die to contact the shell holder reaching press cam over. This takes any slop out of the press and gives more constant shoulder location.



Below in the past I would use feeler gauges adjusting the die down until the correct shoulder bump was achieved. The problem with this method is the air gap between the die and shell holder that allows any flex in the press to effect the amount of shoulder bump.



There is nothing wrong with markm's method of just using a simple drop in case gauge. "BUT" with more toys (gauges) I find I have to bump the shoulder back less and get less brass spring back after sizing. I use the +.004 competition shell holder and I'm loading for three different AR15 rifles.

Head clearance is the air space between the rear of the case and the bolt face. And excessive head clearance will allow the case to stretch and cause case head separations. Meaning being able to measure your fired cases with the Hornady gauge allows you have minimum shoulder bump and less head clearance.



And guess which case gauge is better at checking case diameter. I use the red JP Enterprise for my final "plop test" of my loaded rounds, this gauge is made with a finish chamber reamer and is a smaller diameter than the Wilson or Dillon gauge.



markm, "He who dies with the most toys wins."