I have new Lapua brass and am dreading getting it through the first firing and wondering if my experience/expectation is different than yours.

All of what I am about to write is specific to Lapua .308 Win (7.62 X 51) virgin brass.

It seems like the first firing is a waste of good components. I use Varget and 175 gr. SMKs and whether I run the brass through the sizing die (Redding Type-S small base full length die, no expander ball & .335 bushing) or not, the velocities are way off to the low side.

For a magazine length load out of a 22" suppressed Remington 5R based rifle, I load a 175 gr. SMK to an OAL of 2.81" with 44 grs. Varget and a GM210M primer. This combination produces a stable velocity of 2675 FPS with an SD in the 6 to 7 range in Lapua brass that has been fired one or more times . At 100 yards, the group size is consistently between .5 and .8 MOA. My data shows that it takes .3 grs. more Varget to get that same velocity out of the virgin brass, however, the group size is always significantly larger - .9 to 1.4 MOA.

What do you guys do? Would it be smarter to load with cheap pulled projectiles, cheap primers and essentially shoot into the berm not expecting any kind of groups with a narrowly focused goal of getting through that first firing?

Thanks for your input,
Henryrifle

If you are fire forming brass, certainly use cheap bullets. When i am dire forming i use them as fouling shots befire my serious range session. Yes it takes awhile to get a decent quantity of brass? But then i'm not wasting bullets or my bbl unnecessarily.

Fire-forming cases is all about "WASTE."

You're WASTING powder, a primer, and a bullet simply to get the CASE to fit the chamber. Welcome to the real world of reloading!

Having to add that much more powder makes no sense at all unless I'm understanding something wrong. Is your historical data all with the same lot of components? Put your expander back in your die and run it through the necks, or use a mandrel. Then chamfer inside and out. The goal is to create consistent neck tension on the virgin brass. At a 100 yards, unless things are way out of whack it's hard to believe properly prepped lapua brass won't produce good results on the virgin firing.

I'm going to echo (loudly) what jelrod1 just said. I have never found much if any impact point difference at 1000 yards from when I'm using virgin brass or non-virgin brass.

I never resize virgin brass as there is absolutely no benefit to that and plenty of downsides. I use a -.002 mandrel to round out the mouth and then run the (now less virgin) brass through my Giraud trimmer to give it a nice clean chamfer, deburr and trim and then I prime it, load and go shooting.

Yes, there seems to be a slight decrease in potential precision, but I have won matches with virgin brass. I prefer to take non-virgin brass to BIG matches, but I do not load it any differently.

Contrary to Hansgruber, I don't consider it a waste. I will tell you that in competition circles, "fire-forming brass" is probably the number 1 excuse..., which quickly gets invalidated when someone says something like "I just shot my best string ever, and I'm fire-forming."

Unless by fire-forming you mean making a specific caliber case into another caliber, I would simply ignore it, load it normally and go shoot. I believe you are keeping your cases in separate boxes and keeping track of the firings. That's the best thing to do.

Good to know. I only shot 50 of them today and have a lot left to use. Adding .3 grains of Varget did bring the velocity up to the same as my several times shot Lapua.

I am surprised to hear, NikonUser, that you experience little or no difference between virgin and fired brass.

I am afraid to write this because I know I am asking for criticism of the load I am using in this rifle but I'll risk it. The load I use likes 2665 to 2685 fps. I often compare it to a two-stroke dirt bike. It is on the pipe or off. (If you don't ride dirt bikes, two stroke bikes are either on the pipe and making tons of power or off the pipe and bogging.) If you get outside of that MV range the groups fall apart. Shooting virgin brass with the 44 grs. Varget does not yield a MV in the range given above. 44.3 does.

I've heard what you said and will reconsider what I am doing.

Thank you again,
Henryrifle

No experience with Lapua 308 brass. Do have experience with Lapua 6br, 6.5x47 and 6.5x47 necked down to 6x47. Wouldn't hesitate to shoot a match with virgin brass, done it several times. Velocity might be slightly different compared to a fired case, so what, doesn't matter!

If the varget or brass is of different lots then you are easily within the differences that could cause. If all testing was concluded from the same lot numbers of components then there's not much that can cause this as long as you feel comfortable the seating depths, scale,primers, etc are equal. Not ensuring the necks are consistent is a possible cause that would need to be ruled out. That won't happen by running virgin brass necks through a bushing die without the expander. It just can't smooth out the imperfections in virgin brass like doing it with the expander or a mandrel can. After firing, as long as the chamber is concentric, remove the expander and enjoy the much easier sizing.

If these are different lots of varget or brass it's not really a big deal, just takes the work to make them equal. Properly prepped virgin brass is certainly capable of good results and can have very good ES/SD even if a little upfront work is needed.

I did say I don't see a difference on the target when it comes to elevation. It's difficult to be sure because of two things:

1- I would never shoot virgin and non-virgin brass in the same string, unless I really didn't care about the score, (which is never.)

2- I usually make an elevation adjustment at the beginning of every string because conditions change during the day. It gets warmer and the bullets fly faster or I have even seen it when a cold front comes in and the temperature drops and so do the bullets.

Because of that, I could never be sure if it's virgin brass or not.

One thing I do not for sure though is that virgin brass has varying neck tension even after I run it through a mandrel. Some necks are looser than others, and that WILL show up on target. Which is why I never take virgin brass to a big match. One way around that would be to neck size, without touching the shoulder, but I don't do that.

I should also point out that my chamber is very tight and when I resize fired brass it's right back at virgin size or close enough to make no difference.

[QUOTE]Originally posted by NikonUser:

One thing I do not for sure though is that virgin brass has varying neck tension even after I run it through a mandrel. Some necks are looser than others, and that WILL show up on target. Which is why I never take virgin brass to a big match. One way around that would be to neck size, without touching the shoulder, but I don't do that. [QUOTE]

I prefer the neck size method over the mandrel for the reasons you list. Using a bushing die with expander I don't feel the brass is being overworked in any way detrimental that first time. Or, at least I've never been able to gather any data proving otherwise, and that's assuming precautions are taken not to size anything other than the neck. I try my best to make the first firing count and feel that better duplicates what's going to happen further down the road.

Even with that I still wouldn't mix with the others on a string and agree there is more potential for slight differences that could bite when it matters, and get the point.


To the OP:
There are so many variables that exist between components, particular rifles, equipment and such that it's just really hard to diagnose some problems without everything in front of you. That just leaves guesses and suggestions. My suggestion is run your virgin brass necks through the bushing die with expander and chamfer everything before loading. If lots are the same that may just get things back to where they make sense to you. If lots are different then at least you shouldn't be seeing performance issues due to varying neck tension and will just have to adjust the load accordingly.

jelrod1, offgrid and NikonUser:

Your responses are very enlightening and instructional--thank you.

Lately, just as I begin to think I am understanding many of the important factors relevant to consistent hand loading and internal ballistic performance, you guys remind me that I still have a long long ways to go. Happily, hand loading is interesting, challenging and a fun learning experience.

WARNING Long Read Ahead

If this helps to bring any closure, I have 80 pieces of Lapua from my original purchase that I have been using regularly. I recently introduced the remaining 20 from that same lot into my shooting rotation. I loaded them exactly the same way I load the fired brass, including first running them through the sizing die (no ball).

The brass that has been fired multiple times yields a consistent velocity from the same lot of Varget, the same lot of projectiles and the same lot of primers loaded to the same OAL . In addition to a consistent and known muzzle velocity, these loaded components also yield an acceptable group size that averaged approximately .7 MOA at 100 yards. The 20 new pieces of brass all shot 30-35 fps slower, but more importantly, averaged 1.1 MOA or 57% larger group size.

Had the group size been unaffected, I would not have posted the original message.

Using 100 new pieces of Lapua from a new lot, here is what I learned yesterday: adding .3 grs. of Varget (still same lot) to this new lot of virgin Lapua brass did make the velocity what I was looking for but, it did not fix the group size issue. I did confirm that once or more fired brass still produced the expected MV and group size and it did.

I do want to point out that this is a production Remington 700 sitting in an MDT chassis with a Timney trigger. There are no other mods to the bolt, action or barrel. The throat is very long. I added this information about the rifle in case custom barrels/chambers and trued actions react differently or to a significantly smaller degree to the differences between virgin brass and fired brass.

Thank you again,
Henryrifle

Thanks for the clarifications. Inconsistencies in neck tension is my best guess to the accuracy differences. Depending on magnitude can affect velocity to a small degree also, and certainly its deviation. With a little more prep I think you will be fine with accuracy on these remaining new cases. The potential is there anyway.

A few more questions. What is the base to shoulder measurement on your virgin cases? What is that same measurement on a fired case and a sized one? What I'm getting at is trying to by some chance see if you're pushing that dimension back when sizing to shorter than new. A remote possibility but have to ask. In theory the virgin case will have the least amount of internal volume. All else being equal that usually doesn't result in the lower velocity you are seeing.

I can easily get that information later today. I can tell you from messing around with Quickload that a sized case with no meniscus holds an average of 54.68 grains of water with an SD of .197 grains and a spread of .47 grains. I know that is useless data without knowing what a virgin case holds or a fired case holds.

Henryrifle

The only other thought I had was that your chamber is longish. When you resize the fired brass do you push the shoulder back about .001 from fired or do you push it back to virgin size?

If it's just back a bit from fired, what is the difference between virgin brass and fired brass?

Depending on the answers we may have something. Please remember that I stated my chamber was very tight and there was virtually no difference between fired brass, resized brass and virgin brass for the shoulder. It's one of the reasons resizing with a small base die is near effortless.

quote:

Originally posted by henryrifle:
I can easily get that information later today.

Henryrifle

If those measurements are kosher then maybe also check the diameters at the shoulder and .200 line up from the base on virgin vs sized cases. Also will be good info to know fired. If sized is enough smaller by using that particular die then there's at least a more edjucated guess as to the cause. My main focus on the remaining would be on the accuracy differences though and would worry most about addressing that by what's already been discussed.

I totally agree with that. It is the accuracy issue that is driving this entire discussion.

I am not jumping to this conclusion because I don't have enough knowledge or experience to do so but it is not difficult for me to imagine that this comes down to the comparatively large chamber in a production Remington 700 vs. a much more purpose built rifle with a match chamber that starts out very close to the dimensions of virgin brass.

Henryrifle

Have not has as much time as needed for this tonight but here is a start. These measurements were made using and RCBS mic for .308. The tool is marked in thousandths so while I can't give you the actual measurement, I can give you the relative measurements.

Let me know if this chart makes sense to you:

I'm not sure I understand but does it mean the virgin brass is smaller than resized brass?

It does mean that.

Yeah, pretty much what I expected, hence the questions. This explains your difference in velocity.

During the combustion in a virgin case, the case expands more than in subsequent firings and this saps a little bit of energy and causes the decrease in MV compared to subsequent firings.

One thinks that a more confined space would produce more pressure, but this space is not confined, it expands. It's not the same as using a thicker cartridge.

This drop may be bringing you out of the accuracy node or at least away from the nice middle. Add to that what may be inconsistent neck tension at the first loading, and that may explain some of the decrease in precision.