New Brass Reloading Help

[bug_eyedmonster]

Howdy!

So I am in the process of reloading for .308, 6.5CM, and 7mm RM, and I seem to be getting mixed info on new brass. I have been loading once fired stuff until now, but have some new brass and wanted to make sure I'm not messing anything up. The 7mm brass is Norma, and there seems to be plenty neck tension, they measure slightly shorter than my once fired stuff, and do not need any trimming. With those, I did not re-size, I just loaded and are waiting to test fire the first 10 rounds. I read that because the cases have not been fired, that I need to test for variances in pressure, so I plan to use a chrono.

The Peterson brass I ordered for the .308 and 6.5 says that I should still run them through the full length sizer though, unlike the 7 mag. Do I run the risk of shortening the cases even more by doing so though? Or so I leave my die set up like I was with the once fired so it is only setting neck tension?

For the 7 mag, I basically measured the overall length with the comparator insert, and used close to the minimum load recommended by the manual to fire form the cases. Am I to do this to ALL new brass?

Thanks in advance for your help gurus, still trying to learn as much as I can with this stuff.

[jimmykan]

There are two lengths measurements to brass:

The overall length that you can trim down with a cutter.

The headspace length that you can size down with a sizing die. To measure this on rifle brass, you need a gauge that has the matching shoulder angle. e.g. The Hornady headspace gauge. Sometimes when you full-length size, the case overall length increases because the brass flows toward the case mouth.

I have Peterson 308 brass. I did not full-length size the cases, just expanded the necks with a K&M Mandrel Expander, and they shot great.

[bug_eyedmonster]

There are two lengths measurements to brass:

The overall length that you can trim down with a cutter.

The headspace length that you can size down with a sizing die. To measure this on rifle brass, you need a gauge that has the matching shoulder angle. e.g. The Hornady headspace gauge. Sometimes when you full-length size, the case overall length increases because the brass flows toward the case mouth.

I have Peterson 308 brass. I did not full-length size the cases, just expanded the necks with a K&M Mandrel Expander, and they shot great.

Thank you for your reply, but I have a few more questions.

1. What do I do if the new brass is shorter than what it should be based on shoulder measurement?

2. Why would the brass need to be expanded at the neck?

3. How do I gauge what to load at based on the shorter (less capacity, higher pressure) case size?

Thanks for your input here, but for some reason, after reading all that I have, I'm all of a sudden super paranoid.

Jerry

[jimmykan]

Thank you for your reply, but I have a few more questions.

1. What do I do if the new brass is shorter than what it should be based on shoulder measurement?

2. Why would the brass need to be expanded at the neck?

3. How do I gauge what to load at based on the shorter (less capacity, higher pressure) case size?

Thanks for your input here, but for some reason, after reading all that I have, I'm all of a sudden super paranoid.

Jerry

1. What do I do if the new brass is shorter than what it should be based on shoulder measurement?

Unless you have a hydraulic case forming tool, e.g. the Hornady or Whidden examples, then the only thing you can do is to shoot the brass as is. Ideally, new brass would measure at the exact same length as the headspace GO gage, or if your chamber was out-of-spec then 0.001" shorter than your chamber's headspace measurement (there isn't a great way to measure this because it requires the bolt to be closed). Shorter than necessary new brass is common. My new unfired Lapua 6.5x47 and 6.5 Creedmoor brass measured about 0.003" shorter than their respective headspace GO gages.

2. Why would the brass need to be expanded at the neck?

I do it to iron out the dents, and ensure the case mouths are round. Also, the mandrel I use is 0.001" undersize from nominal bullet caliber, and after brass spring-back, leaves the necks about 0.002" undersize. This results in nice, easy low-effort bullet seating, and consistent seating depth.

3. How do I gauge what to load at based on the shorter (less capacity, higher pressure) case size?

This is a non-issue. You are probably concerned about the difference in internal case capacity between a shorter case and a "fully expanded" case. The difference in capacity will be on the order of the difference due to variations in other factors like case wall thickness, case case head thickness etc. The variation won't be large enough to pose a safety issue, and perhaps not even large enough to pose an accuracy issue, depending on how precise your other components and loading practices are.

[JackEllis]

If you haven't already done so, check a few of your loaded and unloaded cases to make sure they will chamber in YOUR rifle.

I bought some once-fired brass from a reputable vendor and had to run all of it through a sizing die because NONE of it would chamber. Had the same problem in that particular rifle with factory ammo that had apparently used once-fired brass. I'm guessing what happened to me is not common but checking only takes a few minuts.

You really don't want to find out that you should have sized your new brass after it's loaded.

[bug_eyedmonster]

1. What do I do if the new brass is shorter than what it should be based on shoulder measurement?

Unless you have a hydraulic case forming tool, e.g. the Hornady or Whidden examples, then the only thing you can do is to shoot the brass as is. Ideally, new brass would measure at the exact same length as the headspace GO gage, or if your chamber was out-of-spec then 0.001" shorter than your chamber's headspace measurement (there isn't a great way to measure this because it requires the bolt to be closed). Shorter than necessary new brass is common. My new unfired Lapua 6.5x47 and 6.5 Creedmoor brass measured about 0.003" shorter than their respective headspace GO gages.

2. Why would the brass need to be expanded at the neck?

I do it to iron out the dents, and ensure the case mouths are round. Also, the mandrel I use is 0.001" undersize from nominal bullet caliber, and after brass spring-back, leaves the necks about 0.002" undersize. This results in nice, easy low-effort bullet seating, and consistent seating depth.

3. How do I gauge what to load at based on the shorter (less capacity, higher pressure) case size?

This is a non-issue. You are probably concerned about the difference in internal case capacity between a shorter case and a "fully expanded" case. The difference in capacity will be on the order of the difference due to variations in other factors like case wall thickness, case case head thickness etc. The variation won't be large enough to pose a safety issue, and perhaps not even large enough to pose an accuracy issue, depending on how precise your other components and loading practices are.

Got it, it sounds like I'm totally overthinking this. Thank you!

If you haven't already done so, check a few of your loaded and unloaded cases to make sure they will chamber in YOUR rifle.

I bought some once-fired brass from a reputable vendor and had to run all of it through a sizing die because NONE of it would chamber. Had the same problem in that particular rifle with factory ammo that had apparently used once-fired brass. I'm guessing what happened to me is not common but checking only takes a few minuts.

You really don't want to find out that you should have sized your new brass after it's loaded.

I have checked. The new brass, the once fired brass, and the loaded ammo all fit the chambers. Thank you for the reminder though.

Jerry

[divingin]

What are you expecting from this ammo? Are you looking for one hole groups? One inch groups? Two inch?

In general, for recreational shooters, new brass for a given caliber will be good to go with a couple of exceptions: 1) shipping and handling can damage case mouths, so inspection and/or a run through the sizing die may be called for. 2) depending on what the manufacturer does, it's often good to chamfer the inside of the case mouth a bit to alleviate sharp edges so as to avoid shaving the bullet as it seats.

Doing more than that will likely not hurt anything, but it's also not real likely to help much either.

[pacrat]

When dealing with a batch of new cases. First thing I do, is cycle them through the rifle they are intended for. If they fit, they fit. I neck size/expand/chamfer, and load.

It takes less time to run new cases through the rifle. Than it does to lube, size, then clean lube off unnecessarily.

Considering that the purpose of FL sizing is to make them fit the rifle they are intended for. Why FL size cases, that already fit?

I only FL size cases that don't fit.

[fguffey]

Thanks in advance for your help gurus, still trying to learn as much as I can with this stuff.

For the 7 mag, I basically measured the overall length with the comparator insert, and used close to the minimum load recommended by the manual to fire form the cases. Am I to do this to ALL new brass?

I am not one of the gurus; I suggest you ignore those that suggest you fireform. It seems they are trying to overload you with all of this memory work.

Case length from the end of the neck to the case head. I suggest you learn to determine the length of the case from the shoulder/datum to the case head. , I suggest you ask one of the gurus I have never been impressed with fire forming, what is involved? Chamber a round and then pull the trigger; after pulling the trigger you are a fire former.

I am a fan of forming first and the firing.

If you were able to measure the length of the case from the shoulder to the case head you could measure your fired cases. After measuring your fired cases and compared the fired case length to the new case length you could determine the effect the chamber is going to have on you new cases.

F. Guffey

[fguffey]

I only FL size cases that don't fit.

I check the length of the chamber from the datum to the case head first, after measuring I size the cases. I understand it is impossible to keep up with but I have a 30/06 chamber that is .002" longer than a field reject length. When I size cases for that chamber I size them .014" longer than a minimum length/full length sized cases.

When sizing cases for that rifle the press never breaks a sweat.

F. Guffey

[fguffey]

1. What do I do if the new brass is shorter than what it should be based on shoulder measurement?

It depends on who your are; again, I have spent a lot of time digging through fired cases looking for cases that have been fired in trashy old chambers. It looks stranger when I break out these gages no one has ever seen when I am measuring the length of the case from the datum/shoulder to the case head.

When the length of the case is too short for the chamber I find longer cases. Again: And then there is my 30/06 chamber that is .016" longer than a minimum length case from the shoulder to the bolt face. I solve that problem with a 280 Remington case.

F. Guffey

[fguffey]

The 7mm brass is Norma, and there seems to be plenty neck tension,

Bug Eyedmonster, Finally I have found a reloader that can measure neck tension; Problem, I do not have a chart that converts plenty to a value.

F. Guffey