Effect of # Firings in Brass on Load?

[woojos]

I'm still new to the reloading and so far have been loading from a stock of new brass. I'm curious to what effects on accuracy/precision shooting once, twice, thrice, etc. fired brass will have on a chosen load.

I was able to acquire enough Varget to keep me shooting for awhile, and I'm going to start load development on it soon.

I was wondering if I should do load development in used brass instead of brand new?

Does the continued recycling of brass yield a signficant change to the efficacy of a chosen load?

I'm an engineer by trade and this reloading theory falls into the design and analysis of experiments which I have some training in. I don't want to get carried away and start sampling every single experimental combination, especially the number of brass firings. I would love to do it, but I don't have the time or money currently.

Also, does any know where I can obtain a copy of "Rifle Accuracy Facts" by Harold Vaughn by any chance.

 

[M14 Shooter]

One difference is after multiple reloads the brass will get harder.This can effect neck tension.It usually takes 4-5 reloads to cause this problem.Annealing brass will stop this from being a problem.

The real issue with brass is how consistent you size your brass and the methods you use.Necks that are are not straight due to a bent decaping stem or other reason will cause high run out.The more consistent you are the less run out you will have.The key is to use quality brass to begin with.(Lapua,Norma,RWS and Lake City LR)
Low quality Brass will just cause you a lot of issues.
Regards,Mike

 

[rsplante]

One difference is after multiple reloads the brass will get harder.This can effect neck tension.It usually takes 4-5 reloads to cause this problem.Annealing brass will stop this from being a problem.

The real issue with brass is how consistent you size your brass and the methods you use.Necks that are are not straight due to a bent decaping stem or other reason will cause high run out.The more consistent you are the less run out you will have.The key is to use quality brass to begin with.(Lapua,Norma,RWS and Lake City LR)
Low quality Brass will just cause you a lot of issues.
Regards,Mike

+1 on the annealing. I have heard that most quality brass can go 4-5 firings between annealing before necks start to split; however, some have said they anneal after as little as two firings in the interest of consistent neck tension for accuracy. That might be overdoing it; but, I cannot see any harm in it, so that is what I plan on doing when my Giraud annealing machine finally gets to me (12 week waiting list, and I am within two weeks) New Page 1 I selected this one because I liked the engineering (I are one too) and the other two biggies New Case Neck Annealing Machine and Rifle Shell Case Rotary Annealer cost more and are more labor intensive. They each require you to feed cases one at a time, while the Giraud can be loaded up with a few hundred cases and then it goes to town.

 

[woojos]

I have all Lapua brass and I'm sizing with the Redding Type S dies with a titanium nitride bushing. I planned on annealing every 5 firings.

I may drop that down to 3 given this new information. I'll end up sending it out for now, but if things keep progressing the way they have been, I'll end up buying an annealer at some point. RS, I'm sure you will put yours to hard use.

I don't have a chrono yet but that is on the short list. My last load was well under max charge and I picked it based on group size alone and not OCW or any more involved techniques, so I doubt I'm working the brass that hard yet. I may be chasing some velocity #s to get a 1000 yard capable .308 load with the varget and working the brass harder.

Do I have to worry about the brass thickness at the neck dimishing over time?

I think this would affect neck tension. I'm not sure the neck thickness on Lapua brass, but the bushings I have come in increments of .001".

At some point as the brass thins, will I have to move to a smaller bushing to account for the changing thickness of the brass?

Will the brass become unusable before this occurs?

Do you try to keep your lot of brass at approximately the same # of firings, so even if it isn't consistent with initial load development, at least it behaves the same?

Sorry for the all the questions and I appreciate the answers. My goal right now is to soak up as much info as I can to try and accelerate the learning curve as much as possible.

 

[Mad_Charlie]

If anything the brass gets thicker in the neck area. The primer pocket will probably loosen before you need to worry about it.

Yes, I TRY to keep given lots of brass segregated as to number of firings, but sometimes the greedy grass monster has other things to say about that.

Also you get primer pockets prematurely loosening and other various misfortunes. About the only thing you can do, is the best you can.

 

[woojos]

Thanks for the answers guys.

 

[rsplante]

I have all Lapua brass and I'm sizing with the Redding Type S dies with a titanium nitride bushing. I planned on annealing every 5 firings.

I may drop that down to 3 given this new information. I'll end up sending it out for now, but if things keep progressing the way they have been, I'll end up buying an annealer at some point. RS, I'm sure you will put yours to hard use.

I don't have a chrono yet but that is on the short list. My last load was well under max charge and I picked it based on group size alone and not OCW or any more involved techniques, so I doubt I'm working the brass that hard yet. I may be chasing some velocity #s to get a 1000 yard capable .308 load with the varget and working the brass harder.

Do I have to worry about the brass thickness at the neck dimishing over time?

I think this would affect neck tension. I'm not sure the neck thickness on Lapua brass, but the bushings I have come in increments of .001".

At some point as the brass thins, will I have to move to a smaller bushing to account for the changing thickness of the brass?

Will the brass become unusable before this occurs?

Do you try to keep your lot of brass at approximately the same # of firings, so even if it isn't consistent with initial load development, at least it behaves the same?

Sorry for the all the questions and I appreciate the answers. My goal right now is to soak up as much info as I can to try and accelerate the learning curve as much as possible.

Part of the reason I did not go with Lapua brass is that I wanted to process brass once per competition season, so I got 1000 virgin LC11. Two things have happened since then, one, I found that between testing and a second competition each month, my brass does not last anywhere near a season. Two, I found that I spend so much time processing brass that I may as well bite the bullet (unintentional pun) and get Lapua or Norma brass. (when I bought 100 Lapua in .223, they cost about $.70 each, I have spent over 5 times that in my time processing the LC brass (not that I will necessarily spend less time on the Lapua, but I am seeing that the base price for the material is cheap compared to what I have invested in the brass.) As a result, the grass monster does not get ANY of my brass. I built a brass catcher, and I account for each piece of brass before moving on. The chrono is a mandatory item for load development. In my opinion, the ES and SD are more important than group size since they are just an indication of variations in velocity but unless you are a VERY good shot, your hold will have as much or more influence on group size. Also, wind will affect your group size (that is why you should not be looking at group size, but at vertical dispersion of the group). The only exception, and here I am not sure yet how much of an influence it has, but I have read that the barrel flexes up and down, and also in a spiral pattern. Where the last inch or two of the barrel is pointing when the boolit exits will also affect your spread, but this is getting into heavy voodoo and I am just learning about it now. Browning made a rifle with what they called a BOSS system which allowed you to "tune" the barrel in an attempt to address this problem. I understand that it did not sell well so they stopped making it.

In any event, the easiest parameter to measure with any degree of certainty is velocity. There are several inexpensive chronographs out there (~$100). I bought one of them and it drove me crazy with dropped measurements or repeating the measurement (same thing) but I did not know which was which at the time. I finally decided that for my peace of mind, I was going to be certain of my numbers and bought the industry standard, an Oehler 35P. They aren't cheap (~$600 incl tax) but they make two measurements on each shot, a 2' and a 4' measurement and compare them. If they are outside of some predetermined range, the Oehler flags the measurement with an asterisk so that you know it is suspect. So far, it has not been perfect, but MUCH, MUCH better than my first chrono, and I Trust it. (I'm a CDO Engineer. That's the same as OCD, but the letters are in alphabetical order, as they Should be!)

I'm only on my third firing of this batch of 1000 cases, so I have not noticed any change in neck thickness yet. I believe Mad_Charlie is correct though. I have read that brass tends to flow towards the neck (which is why you must trim the brass for length) and I have also heard that brass flows into the head area. I read somewhere that normalizing the primer pocket is not a one time thing, which indicates to me that primer pockets do not necessarily get larger, but may even get tighter. I have not checked that yet either. I can see why some of this stuff takes years to learn. I do go through the entire 1000 before reusing them. I also sort them by .1gn lots. The benchrest guys sort them by water volume, but it seems to me that with the possible exception of brass flowing to the head, if you are using the same lot of cases, and you full length size them, if the weight is exactly the same, the interior volume should be exactly the same. YMMV, I have gotten some disagreement on this point.

 

[woojos]

The only exception, and here I am not sure yet how much of an influence it has, but I have read that the barrel flexes up and down, and also in a spiral pattern. Where the last inch or two of the barrel is pointing when the boolit exits will also affect your spread, but this is getting into heavy voodoo and I am just learning about it now.

In the book I mentioned, Rifle Accuracy Facts by Harold Vaughn, I heard the author tested a bunch of variables in his loads and saw a sinusoidal variation in vertical POI after accounting for differences in velocity. I think this is the heavy voodoo stuff you mentioned. I'd really like to read that book but it is out of print and I've not been able to source it.

This is another reason why I skipped over considering the magnetospeed chrono. I figured strapping a big device to the end of your barrel would change the harmonics of the system and ruin one piece of the equation that should be held constant. I'm still very new to this and seen major changes in POI from my bipod working itself loose and it isn't even touching the barrel.

Thanks for the all the info. I need to buy a better notebook so I can start keeping track of all this stuff.

 

[sinister]

There's a fellow on AR15.com who has done an experiment trying to figure out longevity of range pick-up brass.

He started with 100 cases of unknown origin, picked up off the ground at his local range.

He figured between firings, resizing, annealing occasionally, and lost brass he got 21 firings. The majority of his case failures were from neck splits and loose primer pockets. He definitely saw a difference by annealing (stress-relieving and softening the brass that had been work-hardened by sizing and the the passing of the sizer ball).

Originally Posted By Scorpius:

Now...the bottom is 1-21 this is the number times fired. The neck splits at the count after firing. So example firing 21, post firing 7 rounds had neck splits.

The red lines. This is when I annealed PRE SIZING. So for example at fired 3, this means that on the 2nd firing I brought them home, cleaned, deprimed, annealed

(by hand) then sized, reloaded. I almost hate to say it but looking at the data and how i sometimes waited a little longer to anneal, this chart appears to at least

suggest annealing should happen pretty much every other time. When I went too long between annealings it appears it wouldn't stop neck splits since in essence the

damage was already done. hmmm.....maybe I should redo this test. (Anyone got a giraud for sale ) my fingers couldn't take it much longer.

Anyhow....simply my interpretations. Would love to hear any supportive, contrary so this research helps us pave forward (at least for .223)

After 21 firings these are some of the remaining cases. Although dinged on the exteriors from feeding, ejecting, and hitting parts of the upper and brass deflector these are still going strong. Pretty impressive for random range pickup brass off the ground, cycled through an auto loader.

 

[rsplante]

This is another reason why I skipped over considering the magnetospeed chrono. I figured strapping a big device to the end of your barrel would change the harmonics of the system and ruin one piece of the equation that should be held constant. I'm still very new to this and seen major changes in POI from my bipod working itself loose and it isn't even touching the barrel.

Thanks for the all the info. I need to buy a better notebook so I can start keeping track of all this stuff.

I recently observed a minor battle on this site between Oehler fans and Magnetospeed fans. I completely agree with you. I usually run a ladder test and chrono simultaneously. The groups HAVE to be affected by hanging a chunk of iron off the end of the barrel. Also, I want to be able to use it to chrono pistol rounds. Nowhere to hang a magnetospeed on an automatic pistol.