New brass and first firing

[DLT]

I recently had a barrel chambered savage nut barrel and installed it with a go gauge at home. Once I torqued it down I put 1 piece of scotch tape on the gauge and tried to close the bolt and it wouldn’t close. It’s my 7th or 8th nut barrel install so all is good there.

My once fired brass from new has grown .007. Should I burn 50 rounds at reduced loads ? Not worry with it ? Or try and create a false shoulder ? It’s a hot cartridge and I want my brass to last as long as possible. Thanks guys

 

[RegionRat]

Just to make sure we got the whole story.
1. The Go Gage is tight with tape.
2. The virgin brass is growing 0.007" on the first cycle.

Name the cartridge?
Name the brand of the virgin brass?

How did this brass look when compared to the Go Gage before firing?

How does the brass compare to the Go Gage after firing?

We need to understand how the virgin brass ties to the chamber size. While the growth is good to understand, nothing ties it to the chamber yet.

We can use the Go Gage as a transfer standard to understand how your virgin brass fits the chamber, and the cartridge name and brass tells us what to expect after the second, third, fourth, etc., cycles and if it is worth cranking down on the headspace.

 

[DLT]

It’s a 22 creedmoor. New Peterson brass is being used. I don’t mind cranking down the headspace but I do not want to get into trouble with dies not being able to size them. Visually the new brass compared to fired brass has a much more rounded shoulder angle. I do not have the gauge on hand to measure but I can maybe later this evening, I used my uncles gauge as he’s been shooting 6.5 creedmoor for sometime and never had any brass problems in his rifle. In the past I sure wouldn’t have thought about measuring the first firing but the more experienced I get I think I need to measure everything. Honestly I think new brass is just undersized. I’m real particular about having my headspace set snugly so I double and triple check onece installed.

And guess what happens when you’re in a hurry ??????? Did not take time to make sure a little primer proudness was not affecting my measurements. It much closer to about .004 growth. Not .007 that I was worried about

 

[dellet]

Having just gone through this with someone else, shoulder angle and whatever you’re using for a gauge insert to measure matter. But the Creedmoor cartridge measurements for base to shoulder, and headspace have about a .004” clearance when you have a minimum chamber, and brass sized to minimum SAAMI. Then add another .010” for maximum chamber, minimum brass. If the brass is undersized, which is not uncommon, or shoulder not formed to your chamber angle,, growing over even .010” would not be surprising, as much as .020” in a factory rifle isn’t off the table, with some cheaper brass.

 

[RegionRat]

It’s a 22 creedmoor. New Peterson brass is being used. I don’t mind cranking down the headspace but I do not want to get into trouble with dies not being able to size them. Visually the new brass compared to fired brass has a much more rounded shoulder angle. I do not have the gauge on hand to measure but I can maybe later this evening, I used my uncles gauge as he’s been shooting 6.5 creedmoor for sometime and never had any brass problems in his rifle. In the past I sure wouldn’t have thought about measuring the first firing but the more experienced I get I think I need to measure everything. Honestly I think new brass is just undersized. I’m real particular about having my headspace set snugly so I double and triple check onece installed.

And guess what happens when you’re in a hurry ??????? Did not take time to make sure a little primer proudness was not affecting my measurements. It much closer to about .004 growth. Not .007 that I was worried about

You did a good job installing the new bbl, no worries there. When you put a 0.002" piece of tape on the gage and it is tight, you are doing well.

Measuring your virgin brass is important when starting up a new rig. To be honest, you will want to detail inspect a handful of cases in the virgin state, and for several firings afterwards too.

All those other dimensions matter, especially the diameters. The corollary is to see what your brass prep does to the brass during the first several cycles till you are confident you know what the process is doing and that it is stable.

With a given sizing die, there is a direct control on the shoulder datum length, but only a weak relation to the diameters. If the brass, die, and chamber don't coordinate well on the diameters, the adjustment isn't going to solve issues. That is why you will want to measure everything up front for several cycles, and then you can cut back.

Good Luck and in for the range reports.

 

[ronemus]

Most manufacturers make brass to SAAMI minimum dimensions, which is often 0.006" under the length of a SAAMI minimum chamber; thus it's normal for brass to lengthen after the first firing. That amount of stretch won't create problems as long as you don't size the brass excessively when you reload.

 

[searcher]

I'd just run with what you are doing. That .007" "growth" is not a concern. If you adjust your barrel nut to fit the brass with little space, you could risk having to readjust it if you change brass brands or lots unless you push the shoulders back the same amount - resulting in similar brass stress. Since you used gauges, you should be good to go. Having the shoulder blow forward will not materially shorten the life of your brass. I've got a lot of .220 Russian brass that got blown forward that much when fireforming to 6PPC and the brass gets 20-30 loadings, no problem.

 

[SKWERLZ]

I recently had a barrel chambered savage nut barrel and installed it with a go gauge at home. Once I torqued it down I put 1 piece of scotch tape on the gauge and tried to close the bolt and it wouldn’t close. It’s my 7th or 8th nut barrel install so all is good there.

My once fired brass from new has grown .007. Should I burn 50 rounds at reduced loads ? Not worry with it ? Or try and create a false shoulder ? It’s a hot cartridge and I want my brass to last as long as possible. Thanks guys

Personally I’d do a false shoulder.
It’s not a terrible amount at .007 but it’s so easy to do and 100% not worry about it later.

 

[DLT]

Personally I’d do a false shoulder.
It’s not a terrible amount at .007 but it’s so easy to do and 100% not worry about it later.

I got home yesterday from work to my loading bench and used my hornady headspace comparator with the correct insert which was “D” it visibly sits closer to the shoulder on a creedmoor case. I deprimed 5 cases, using it I got only .002 difference between new brass and once fired. All is well if you slow down and use correct tools and processes the first time lol.

 

[JMayo]

Rim thickness can vary between cases. I do not sweat the shoulder bump as s long as i get a good medium that makes the longer fit and the shorter not be too short.

 

[DLT]

Rim thickness can vary between cases. I do not sweat the shoulder bump as s long as i get a good medium that makes the longer fit and the shorter not be too short.

Correct. I’ll get my bump set. Just thought I had bad undersized brass from the get go turns out all is well Extremely well

 

[6.5 forever]

I got home yesterday from work to my loading bench and used my hornady headspace comparator with the correct insert which was “D” it visibly sits closer to the shoulder on a creedmoor case. I deprimed 5 cases, using it I got only .002 difference between new brass and once fired. All is well if you slow down and use correct tools and processes the first time lol.

You must always deprime before taking measurements on the case. I think you understand that.
This whole process is fire forming virgin brass.