Head space on new rifle

Have a new rifle I just built chambered in 30 Nosler. I started with new ADG brass and shot 50 rounds through it to break in and kind of get a start in load development. Most of the brass is coming back at 2.1835" after being shot, and 2 are coming back at 2.1850". Looking at my reamer print out, it's showing a min of 2.1877" and max of 2.1977. So my question is this… would it seem that I should only neck size these since they did not get blown out all the way to the exact chamber dimensions and are still .002" under spec? I did take the 2 biggest pieces and insert into the chamber and the bolt closed just fine.

If you're bolt closes on your fired brass before sizing, I say go for it and neck size until your brass is formed to your chamber. That's what I do anyways.

Agreed, keep going till its fully formed before doing any real load development. Often while doing a pressure test, you will expand a case to the point in which the case will no longer easily chamber and the shoulder needs to be bumped back. Alex Wheeler has a video on how to find the proper shoulder set back once you get to that point.

I just went through basically this same thing... once fired brass was hardly changed compared to factory (Lapua brass). Since they chambered fine, I used the Eric Cortina tape trick to compare my shoulder to the chamber. I can't find the video, but put scotch tape on the casing base, roll the edges on a hard surface, then peel the excess tape off the perimeter of the base. Then measure it in your comparator and see how it chambers. It will likely be very tight or won't chamber, giving you a better idea of where your shoulder is in relation to your chamber.

I am new to this so take my suggestion accordingly!

What are you using to measure the shoulder? If your using a comparator then the numbers may not be the same due to not being on the datum line or same spot as the reamer print.

cajun said:

What are you using to measure the shoulder? If your using a comparator then the numbers may not be the same due to not being on the datum line or same spot as the reamer print.

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Hornsdy gauge

Then what I said is true. The Hornady is a comparator so one bushing is used for multiple calibers. So it's probably not measuring from the same spot as what your print has. Did you check and see if the fired brass chambers.

cajun said:

Then what I said is true. The Hornady is a comparator so one bushing is used for multiple calibers. So it's probably not measuring from the same spot as what your print has. Did you check and see if the fired brass chambers.

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Yes, it chambers just fine

Then I would neck size or back off your sizing die to not bump shoulder until the brass is fully formed.

thanks everyone. I watched the Eric Cortina video and used his method using scotch tape. The proper headspace on my rifle is 2.1850". I will FL size the brass but will be careful not to bump the shoulder on this firing.

Looking at your numbers your around 2 thou or a little less from where you need to be. Thats not much.

I have a custom in 30 Nos. The adg brass needed the shoulders bumped when the brass was new. Then they go 3 firings before they need bumping.

Always wait until the brass fully forms to your chamber and the bolt gets sticky. Then start measuring with your comparator.
You can use the comparator numbers, or the tape method, or remove your firing pin and ejector to take pressure off the brass and then chamber the brass. The bolt should easily drop half way.
If you are fire forming your brass, start with a low powder charge and jam the bullets. Jamming the bullets forces the case back against the bolt face so that any expansion is in the shoulder area forward. If you don't, you risk the case head area being expanded and pushed back against the bolt face which can lead to case head separation.

Thanks Swampbug. I am new to loading and just assumed that firing brass made it form tot he chamber. It wasn't until I started measuring and trying to size that I realized it hadn't. This is good info that I hadn't seen or heard before.