Fired Case - Shoulder - Base Measurement Variation

[Phil3]

New to reloading, and measured case shoulder to head on Blackhills remanufactured 223 Remington ammo, once fired out of my AR15. I am using this measurement to set up dies for shoulder setback of about .004". I measured 47 cases, all deprimed and cleaned. They came out as follows.

8 = 1.430"
18 = 1.431"
16 = 1.432"
4 = 1.433"
1 = 1.434"

Do I set back the shoulder from the average of these (about 1.4315"? I could not see anything on the shoulder or head of the case that could account for the longer ones. Is this just a normal variation one can expect to see?

The measuring tool are calipers outfitted with a clamp-on Sinclair comparator body and shoulder insert for 22 caliber.


- Phil

 

[MinorDamage]

Re: Fired Case - Shoulder - Base Measurement Variation

Don't worry about the shoulder if it is a semi unless you are crushing cases. Unless the die is messed up it won't crush them. Take the ram all the way up, screw the die down until it touches, lower the ram, and tighten the die one more quarter turn. All semi brass should be full length sized.

Josh

 

[427Cobra]

Re: Fired Case - Shoulder - Base Measurement Variation

Decapper first, sometimes the primers get pushed out a cunt hair and mess with headspace measuring, then make sure there is no Ejector marks as they also change the reading

 

[Phil3]

Re: Fired Case - Shoulder - Base Measurement Variation

The brass is deprimed, but have noticed that when the case is held up the light when clamped in the calipers, that there is some unevenness between the caliper blade and the case head. I will look at that more closely to ensure there is no grit, burr, etc., screwing up my measurement.

- Phil

 

[bignada]

Re: Fired Case - Shoulder - Base Measurement Variation

You are probably taking more pains that BlackHills did when remanuing.

Try loading some virgin brass and firing that. Winchester is the best choice or LC if you can find unfired virgin. You need to know what your chamber dimensions are.

What are you measuring with? The RCBS Precision Mic is a great tool, as is the Wilson.

Are you loading for more than one gun? If the other one is also a semi-auto, need to measure cases from it also and use the shortest OAL dimension to set sizing. Might even go .005" under to be sure if using once-fired cases.

 

[Phil3]

Re: Fired Case - Shoulder - Base Measurement Variation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bignada</div><div class="ubbcode-body">You are probably taking more pains that BlackHills did when remanuing.

Try loading some virgin brass and firing that. Winchester is the best choice or LC if you can find unfired virgin. You need to know what your chamber dimensions are.

What are you measuring with? The RCBS Precision Mic is a great tool, as is the Wilson.

Are you loading for more than one gun? If the other one is also a semi-auto, need to measure cases from it also and use the shortest OAL dimension to set sizing. Might even go .005" under to be sure if using once-fired cases. </div></div>

I have 500 new unfired Winchester cases which I will fire and measure. But would not the BlackHills remanufactured give me my chamber dimensions since I have fired it through my rifle?

I am measuring case shoulder headspace with calipers, a Sinclairs comparator holder and 22 caliber insert. This is the exact same setup used in the Reloading 101 sticky.

I am reloading for just one gun, an AR15, with 223 Remington SAAMI spec chamber (Krieger chambered).

- Phil

 

[Fuzzball]

Re: Fired Case - Shoulder - Base Measurement Variation

"Is this just a normal variation one can expect to see?"

Pretty much so. What you're seeing is the actual variation in caxe hardness and resulting spring back, there's nothing we can do to change that.

 

[427Cobra]

Re: Fired Case - Shoulder - Base Measurement Variation

Blackhills brass is made by Winchester