308 Winchester Case Capacities

[308Loader]

Some how I don't think you will be able to keep this post on track until the end of June.

[Reloadron]

Some how I don't think you will be able to keep this post on track until the end of June.

Right now my focus is Friday.
One day at a time.

Ron

[Metal god]

I've done a good amount of case volume measuring . I've always done it with fire formed cases . The reason being is as cases are work hardened they have different amounts of "spring back" from case to case and manufacturer to manufacturer . This can actually cause inconsistent volume measurements from case to case . Add in range pick up brass with no known history and I'm not sure how consistent sized cases will be .

That said I'd love to see what those cases produce as far as internal volume after they've been fired all from the same rifle . This could show for sure if measuring case volume with a fire formed case gives a more consistent result .

Truly waiting at the edge of my seat for the results .

EDIT : just got to thinking , I already have a lot of case volume data from multiple manufacturers in both 223/5.56 and 308 cases . Now all I need to do is go size those same cases and re-measure . Unfortunately I no longer have the exact cases I used in the first measurements separated from the greater lots of brass they were pulled from . Not sure I'd get the true results I'm looking for by randomly pulling cases from those same lots of brass .

Well let me put some thought to this , maybe I do the test again using all the same brass this time . I have lots of at least 8 different brands of brass , this includes different year stamps of LC brass to also include LC-LR brass .

The thing is , that would take me a few months to complete . I to have way more things going on in my life then I really have time for . Adding to that is really not the best idea right now . I can pull from the existing fired lots and size those and see if there is a difference then the fired cases from the same lots . That could be done relatively quickly compared to having to actually load and shoot the rounds as well .

Now lets just see how motivated I am . I've been so busy lately that I actually have to schedule time to do nothing just to be sure I get some rest .

[Reloadron]

Metal god, if you can manage the time then please do. My brass was all once fired in the same rifle with the exception of the GI brass (WCC and LC). All the brass was run through a full length set of RCBS dies and sized the same. I did measure each case following sizing using an RCBS Precision Mic. The outside dimensions are about as close as I'll ever get them.

Ron

[Metal god]

Reloadron : I'll see what I can do . I'll check what fired cases I have now on hand . I could measure the fired cases then turn around and size those same case and remeasure . That I think could be done in a couple hours time . I think I can do that some time soon . My guess though would be most if not all my existing fired cases are LC only brass . I've not loaded RP , Win , or Fed cases in quite some time ( at least 3 years ) . Now I know I have some of those cases laying around or even separated into lots but I won't remember the history of them . I have multiple rifles in those same calibers so knowing which rifle they came out of may prove difficult .

That said I know I have LC brass and WCC brass with a well documented history to pull from .

I'll see what I can do .

[Reloadron]

Metal god, anything you could kick in is most appreciated. While I am retired time has been consumed with other things right now. I know the drill with time.

Thanks
Ron

[Jeffm004]

I look forward to your results.

It is my untested opinion based upon experience that weight sorting does not mater nearly as much as head stamp origin sorting. This suggest neck tension is more important than case volume. I have a friend that turns his necks. I mocked him until I shot them. When it has to be an X at 1,000...

For us mortals, your test results will be interesting.

[308Loader]

"I am the only reloader that..." to your hearts content.

And then there was the assumption

do not want to hear about re-loader's this, that or another.



OMG, you guys make me laugh. thanks

[308Loader]

Ron, I think its too late to pull this one out of the gutter. You have only posted the weights of your test cases and we are on page 2 of nothing to do with the original post. Its been an sad but funny post with no conclusion.

When a reloader writes a post he often wishes to have the topic of his post discussed. And then their is the reloader who often sidetracks the discussion, I once new a reloader like that. He would tell story's of past glory in riddles only he could understand. Trying to impart some wisdom on his peers. I am the only reloader that understands, when the bolt closes and the lights go out, it was a community of shooters that made the read worth while.

Please start a new thread when your experiment is complete, I would love to read your conclusions. Maybe replicate your test and draw my own.

[Mike Irwin]

OK, folks, I've done some thread pruning.

The OP has requested that replies focus on CAPACITY. Has requested it several times, actually.

Not tools, not powder column lengths, not anything else.

If you want to talk about that, start your own thread.

[Unclenick]

Thanks Mike. I should have started doing that on page one. I've been out of the country the last week and made the mistake of thinking I'd keep up by tablet, but connectivity proved too intermittent.

[Metal god]

Ok so what I have on hand with known history to run some capacity test are all 308 cases and are as follows

15 - LC14 twice fired including once reloaded

15 - LC12-LR three times fired including twice reloaded

15 - Fed GMM cases once fired from factory new loaded cartridges

15 - Lapua once fired from factory new virgin brass .

I went ahead and wet tumbled those all today and will do the capacity measurements sometime this week .

Please stand by

[Reloadron]

Thanks for contributing. Lets see the numbers that you have, Take your time.

Ron

[Metal god]

Update and question : Sorry thought I'd get to this sooner but been dealing with caregiver duties for both parents and a aunt as well as trying to work . To top it off I've been sick as a dog the last 5 days . I'll get this done , it's just going to take a little longer then I thought .

So far I've de-primed , wet tumbled , trimmed to 2.000 and weighed each fire formed case I will be using in the test . After all of that I only have 11 of each sample lot noted in my earlier post . I also numbered each case 1 to 11 so I'll actually be comparing the same empty case weight to the same full case weight . The other thing of note is that the LC-14 , Lapua and LC-12-LR all were fired from the same Savage model 10 while the Fed GMM cases were fire in a Ruger PR .

Ok that's were I left off but I've run into a bit of a dilemma IMO . Every other time I've measured case capacity I've left the spent primers in . How ever this time I did not and when plugging the primer pocket with model clay . I found that on some cases but not all the clay would push up through the flash hole into the case . No problem I'd just take a small flat head screwdriver and knock that down flush inside the case . While doing this I came to realize that there is no real way for me to plug the primer pockets with a consistent amount of model clay . Meaning each plug will likely weigh different then the last . Am I wrong in thinking this is going to throw off the whole test ?

I know I can plug the primer pocket then weigh each empty case but there again I'm not going to have the same weight plug in each pocket throwing off the actual empty case weight .

My thinking write now is to either deprime some spent cases and re-seat those spent primers in my test case OR just seat some new primers in the test cases and continue on ????

[Reloadron]

Metal god writes:

Ok that's were I left off but I've run into a bit of a dilemma IMO . Every other time I've measured case capacity I've left the spent primers in . How ever this time I did not and when plugging the primer pocket with model clay . I found that on some cases but not all the clay would push up through the flash hole into the case . No problem I'd just take a small flat head screwdriver and knock that down flush inside the case . While doing this I came to realize that there is no real way for me to plug the primer pockets with a consistent amount of model clay . Meaning each plug will likely weigh different then the last . Am I wrong in thinking this is going to throw off the whole test ?

I can feel your pain on that. Since I only had 50 cases I meticulously, using a flat toothpick, used my same little ball of clay to keep things consistent. I doubt what happened will really have much effect on the overall numbers especially in view of the case count.

I hope to get this science experiment concluded soon but a few things have come up of personal nature which has taken my time away from play. With luck I can resume my normal play time around late June.

Ron

[cw308]

Years back I started out with 100 cases of Rem & Win new brass . Using a standard RCBS F/L die , not knowing of headspace or ogive . A friend gave me his once fired Federal brass , I sized it to give it a try an noticed the same charge almost filled the case . The Federal brass was much thicker, mentioned it years ago on this forum , everyone gave me all good advice . Now I read alot on everything possible to do with reloading . Before I thought for some reason all cases had to be exact , things would be too easy if that were true . More of a challenge this way . Nothing's exact , some groups are better then others , l now think it's just me .

[Metal god]

I was loading some 223/5.56 mixed brass for some plinking rounds . This was using IMR 4320 and 55gr bullets . As I was loading them on average the powder was coming up to the base of the neck/top of the shoulder area . All of a sudden I drop the powder in the case and it fills it to the case mouth . Hmm that's odd I think to my self and I put that case aside . I continue and a number of cases later it happens again . So now I'm wondering if the powder is bridging in the case creating air pockets allowing the powder to sit higher in the case . I tap the case a little and the powder settles a little but not all that much . enough to at least get the bullet seated with out to much compression .

I continue loading with the powder averaging the same place ( base of the neck/top of the shoulder and I come across another that almost over flows . So now I take all three that have almost over flowed and compare head stamps . All three were CBC head stamped . Interesting , maybe it's the cases and not bridging of the powder like I thought . I finishing loading the 200+ mixed brass loads and 7 or 8 of them were the CBC cases and all of those and only those filled the case to the top .

So what to do now I think ? Do I pull the bullets and trash the brass or do I go shoot these and compare them to all the others I just loaded . I choose to shoot them all over my chrono and compare them to a random 7 from the rest .

Sorry to leave you all hanging but I'd rather not go off memory so I need to go find my notes on this . I'll say there was a big difference in velocity and I did a case volume test afterwards with interesting results . Well not really interesting if you consider the results were exactly what was expected . Which was the CBC cases had a much smaller case volume on average then the other 7 randomly selected mixed cases .

I'll go see if I can find the notes on this . Sorry the only reason I'm posting this incomplete is that I don't want to write all this again lol

[cw308]

Metal god
That basically what happened to me , I use IMR 4064 for 308 Cal. I could see the Federal cases were thicker after trimming. Being I'm shooting a mild load 40.8 for a 168gr. SMK the thicker cases worked better for me , with 40.8 grains the powder is at the base of the case neck . That's a accuracy load for 200 yards , which is the maximum distance for the ranges in my area . I only shoot benchrest.

[hounddawg]

I have thought about case case capacity and have to wonder about a few things

One - what scales are you using . A RCBS 750 Rangemaster or equivalent or a Sartoius Entris ? If it isn't the latter then your tolerance is about the same as your SD's in some of the findings.

the FX 120i is a fine scale for just about reloader however it only goes so far, if you want super accurate the you need something that weighs to .0001 grams or 1/10th of a milligram

A single kernel of Varget weighs ± 0.02 grains and the FX-120i increments in 0.02 grain divisions (0.02 gn > 0.04 gn > 0.06 gn, etc) and the linearity (or accuracy) is ± two(2) divisions or ± 0.04 grains.

https://balance.balances.com/scales/1223

Two - I can take cases which have never been sorted for volume and get low to mid consistent single digits in velocity SD. Then I can prep those same cases the same exact way and reload them with the same powder just a couple of tenths higher and gave ES's in the 20's

Three - I have no idea how much gas a powder produces when fired in a rifle but I do know it increases the pressure to about 50K. Now consider the case volume plus the bore volume and think about how much volume .1gn of water makes percentage wise. Edit 1 gn water would be 1/15 th of a CC so .1 of that is going to make how much difference percentage wise?

Just my opinion but it is a total waste of time as far as accuracy loading. However if you like to run your charges to the ragged edge of self destruction I can see a interest

[Metal god]

My notes say :

The mixed brass lot of cases had 13 different head stamps . I pulled 7 random ones out and never looked at what those head stamps were . I compared those 7 random cases to the 7 CBC cases that almost over flowed by shooting them over a chrono .

The load was

Winchester 55gr FMJ-BT
25gr IMR 8208 XBR ( I was wrong when thinking it was IMR 4320 and why I did not want to go off memory )
CCI# 400 primers
FL sized bumping the shoulders .003 and using .244 neck bushing
COAL was 2.240

Rifle - 16" AR

Mixed cases - 2836fps avg , ES-72 , SD-34
CBC cases - 2917fps avg , ES-65 , SD-26

Unfortunately I can't find the case volume data . Now this is by memory but I "think" the CBC cases held 1.6gr less of water but I also want to say it was more like 2.1gr difference but I'm not sure . Either way even the 1.6gr difference in a 223 case seems huge to me and it showed over the chrono .

Side note and goes more to the OP is that I came across my notes from my last 308 case volume test

LC-10 = 54.86gr avg ES - .6gr
LC-12-LR = 54.97gr avg ES-.8gr
LC-14 = 55.12gr avg ES - 1.2gr

So those all seem pretty darn close right . There's what , a total case volume spread of .26gr . So you'd think one should be able to load all those cases pretty much the same . Meaning if 42.5gr of IMR 4895 shot well with no pressure signs in one case . You'd likely be able to load that same charge in the others right ????????? WRONG

Here's the interesting part in all this . The highest charge I can put in the LC-14 cases of IMR 4895 pushing a 168gr HPBT with out getting a sticky bolt lift is 41.5gr at 2580fps .

How ever when testing those same components in the same rifle but using the LC-12-LR cases . I was able to load 43.0gr of IMR 4895 at 2710fps with no sticky bolt lift . Those cases only had a total of .15gr difference in case volume yet I was able to safely put 1.5gr more powder in the LC-12-LR cases with no pressure signs .

I wrote about this here at TFL a couple years ago and the conclusion was that the LC-14 cases are much softer then the LC-12-LR cases . It appears the LC-14 cases are stretching out easier then the LC-12-LR cases are . After now loading the LC-14 case a bunch I believe they are in fact softer . I'm stretching out the primer pockets faster then any other head stamp I've ever used and that's with a mild 41gr load pushing 168gr HPBT .

[cw308]

The scales I use RCBS ChargeMaster 1500 double check with GemPro 250 . I stopped using the thinner cases , Federal , HSM & ADI brass are for some reason thicker walled . All the brass came from my shooting buddy that doesn't want to reload . All cases came from a orange box marked HSM 308 WIN A - Max MATCH . all case weight are in the close range . Stopped over thinking on the cases but size an trim to be exact .

[hounddawg]

I agree on the overthinking, I ran down that rabbit hole myself last year. Gotto the point where I sorted bullets by base to ogive length.

Went back to basics and I am getting good results with some pretty basic techniques and equipment. I shot three ten shot groups at 300 this morning and one ten shot group at 800 which were all sub MOA. I had a half MOA vertical on the 800. Edit - the conditions were pretty much perfect, less than a 5 mph wind and only a light intermittent mirage.

Those groups are good enough for F class as long as they are centered which is the tough part. The case prep was pretty basic with no neck turning or case weighing or anything fancy other than annealing which I think is probably more rabbits foot than anything. Just consistent lengths, firmly seated primers, and proper load development is good for most of us mere mortals who don't wildcat our cases etc etc. I am pretty sure the .1 BR boys will scream sacrilege but so be it.

[Metal god]

hounddawg : although I believe you and I are in the same camp as to how much case prep is really needed to shoot good groups . I don't think case prep and sorting by weight or even case volume is the over all point of the thread . When ever I've heard of guys separating by volume or even weight . They almost always are doing that with in the same head stamped cases .

The OP seem to be talking more in the area of using a different case ( military) and if there case volume is less then standard commercial cases . As well as case volume as a whole and if and or how much it can effect a load .

I think my CBC case test shows quite clearly that case volume matters a lot and does effect performance . Now that's comparing separate headstamps though . Depending on the powder used I may have not even noticed that difference or it may have spilled all over . Example . If I were using a small ball powder like H-335 that barely fills the case to the base of the shoulder at 25gr . I'd likely not even notice that the cases filled a little more . How ever If I were using IMR 4064 or other long stick powder The case would have absolutely over flowed , no doubt in my mind .

My point here is that If you're using quality brass of all the same head stamp . It's not all that likely you are going to run into any real case volume issues . How ever what if you have a nice hot 223 load using Federal cases and then you find a great deal on 500 CBC cases . Well if case volume does not mean very much you'd have to conclude you can just load that same hot charge you're using in your Fed brass into your new CBC cases . But you can't and or should not and likely the reason every manual says if you change any components you should reduce the charge and re-work it back up .

It's my understanding case volume differences from manufacturer to manufacturer in 308 is even more likely not to mention all the other cartridges manufactured .

I find it interesting that the two case volume test I posted earlier really concluded two different things . The 223 showed case volume differences matters a lot while the 308 cases showed even when the case volume is pretty much the same that actually means nothing as well . Which I think over all shows that when you read "when you change any component of a load , you should reduce the charge and re-work it" rings true .

[Reloadron]

Metal god:

The OP seem to be talking more in the area of using a different case ( military) and if there case volume is less then standard commercial cases . As well as case volume as a whole and if and or how much it can effect a load .

I think my CBC case test shows quite clearly that case volume matters a lot and does effect performance . Now that's comparing separate headstamps though . Depending on the powder used I may have not even noticed that difference or it may have spilled all over . Example . If I were using a small ball powder like H-335 that barely fills the case to the base of the shoulder at 25gr . I'd likely not even notice that the cases filled a little more . How ever If I were using IMR 4064 or other long stick powder The case would have absolutely over flowed , no doubt in my mind .

What I was looking for was with the volume differences similar to what I posted is how much will it matter? I really like to keep brass all in the same family when I clean and load. So for example let's say loading Sierra 168 grain HPBT bullets over 40.0 grains of IMR 4895 how much difference might I expect to see in velocity or group? Wish I could measure and look at the pressure curves but not there yet. Anyway, that is what the thread is about. I have the case volumes expressed in cc (cubic centimeters) and curious how much difference it would make for given loads. This does not take into consideration how uniform the necks are in thickness, I should measure them. Anyway, that is what it's all about. The case to case deltas are not very large in what I sampled and I included some GI brass just to have it included. Actually the overall best uniformity was the WCC 10 stuff which has fared really well for me.

Ron

[hounddawg]

Well metalgod, the benchrest boys go bf crazy weighing bullets and computing case volumes, do their load development to the point they get one hole groups with a couple of tenths leeway on their powder charge so there may be something to it.

For me all I care about is getting 20 round hopefully sub MOA groups centered on the X at 300 - 1000. My gun and ammo can do the sub MOA part it is the shooter that screws it up on the centering and wind calls. Reloading is just a mechanical process. I have found it fairly easy to learn and you can get as involved and OCD as you care to get. However I saw diminishing returns on my time invested so I simplified and I am happy where I am at, it's the range technique that kicks my butt

All I am saying is develop what you shoot for BR, tactical, F Class or just blasting away making smoke and noise. It's all just fun