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 .
308 Winchester Case Capacities
- Thread starter Reloadron
- Start date
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
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
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.
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.
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
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
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
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
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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 .
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 .
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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 .
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.
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.
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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 .
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 .
Metal god:
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
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
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
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
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I don't own a chronograph , I use the thicker of the brands because I load pretty mild 40.8 of IMR 4064 under a 168gr. SMK 308 Cal. The stick powder fills the case to the base of the neck , I don't like the powder to shift around in the loaded case . I would think it could have different burn rate or pressure issues . Could it cause having that great group an then that flier comes from left field when you did everything right .
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Yep , when you take the human element out of shooting like shooting off a bench on a full rest where the shooter is really not even "shooting" . That pretty much just leaves the equipment which includes the ammo . If anyone wants to shoot one hole groups . I urge them to never touch there rifle when they shoot just like a benchrester
Us guys that actually hold are rifles when we shoot will never likely notice .1moa differences in a load . You have to take the human out of the equation to see those differences . I know there are some shooters that shoot well enough to notice but there are very few of those .
As my LC-12-LR and LC-14 case comparison seems to indicate . Case volume is also predicated on case quality and hardness . As for lets say a 1gr difference in case volume when comparing cases from the same headstamp and lot . I think you only find out those potential differences by shooting from a machine rest that locks the rifle down , through a chronograph at a distance of at least 600yds . Then measure the vertical stringing . Although doing the first two with a very high quality chrono may do the same thing .
It would seem what case volume , and it's potential variances could cause really comes down to barrel time and when the bullet leaves the barrel in relation to the harmonics of the barrel . If you have a bullet leaving your bore 50 or 100fps slower or faster then the rest . You'll likely have a POI shift with that bullet because of the different position of the muzzle when the bullet leaves the barrel compared to the rest because of the harmonics of the rifle .
I have a great load that shoots sub moa all day out to 300yds using those soft LC-14 cases that have a case volume ES of more then one grain . Now that's me holding my rifle . hmm , well rested on front and rear bags but me still very much in control of the rifle pulled into my shoulder . What does all this mean ? I'm not sure but does put me in the camp of extreme case prep is not needed for the type of shooting I do .
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Added this to a new post just in case some already ready my last post
I have some of those LC-14 case loaded up . I'm going to the range on the 11th . I'll run those over my chrono and see what kind of ES/SD I get with those cases that have a 1.2gr variance in case volume .
Me said:
I have some of those LC-14 case loaded up . I'm going to the range on the 11th . I'll run those over my chrono and see what kind of ES/SD I get with those cases that have a 1.2gr variance in case volume .
I ran about 2500 rounds across my chrono last year and one thing that I will bet the farm on and that is the SD is dependent on the powder choice and the load. Case volumes had no effect as far as I could tell.
I can take 45 cases from a prepped batch and load 15 with 44.0 grains, 15 with 44.4 and 15 with 44.8 grains of the same powder and get SD's from 5 to 30 depending on the powder load . Then go prep those same 45 cases once again choose cases at random and repeat the test and get similar results. I have 200 Peterson .260 Remington cases that get shot, prepped and reloaded randomly and as long as I prep and load them the same they give consistently low ES and SD numbers. I can take those same cases and load them outside of the "flat spot" on my load workups and the numbers jump up
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I don't remember what the ES/SD was on that load but would guess the SD is somewhere in the teens . I did a test a few years ago that showed how I held the rifle effected my ES/SD so I no longer put to much stock in those numbers . It wasn't a lot but I was able to reduce my SD from the teens to single digits just by how I held the rifle .
Unless my SD's are in the 20's+ I more go off consistent group size as to what constitutes a good load .
Unless my SD's are in the 20's+ I more go off consistent group size as to what constitutes a good load .
a consistent hold is important no matter what disicpline you are shooting. I dry fire at least three 30 minute sessions per week practicing cheek weld, follow through, breathing etc. Most of my flyers are attributable to me, the shooter. Not ammo or gun.
I was shooting my tactical build a week or two back at 600. Loaded 5 rounds in the magazine shot them. Loaded 5 more and shot those. When I checked my target my ten shot group was really more like two 5 shot groups that overlapped. I must have changed my cheek weld or grip slightly on my second magazine. Time for more dry firing
at what range ?
take two 168 SMK's one traveling 2700 FPS the other 2675 or 25 FPS slower. Shoot both from a mounted test barrel and action. Point of impact for the slower bullet will be .4 lower at 300 yards, 4 inches lower at 800 yards and 9 inches lower at 1000. That's easily the difference between the ten ring and the nine ring at the longer ranges.
I develop my loads for 600 - 1000 so I want SD's in the single digits. Even at closer ranges the lower my SD the fewer flyers I seem to get.
I see people shoot 1 hole groups at 100 and shoot in the 180's with the same load at 800 with vertical spreads of over a minute and a half
Most of my shooting at distance is only 300yds because that's the distance I have most access to . An SD of 25fps would not be expectable to me . I really don't like it any more the 15fps so that would be something like .25"-ish at 300yds . I'm not sure I can shoot well enough to notice that , in fact I'm certain I can't shoot that well . I mean that's less then a 10th moa . I just don't have the skills or the equipment to shoot that well .
If you have SD's in the teens then you have ES's in the 30's or more. But like you said at 200 and 300 it will not affect POI enough to matter for most of us
I guess my question is if you are not worried about velocity consistency why be concerned with case volume. I have a .223 load that is great for practicing technique, any fliers at 100 - 300 are due to my shooting technique. At 800 it would be all over the paper just on the vertical. On a calm day it would look like someone hung a polka dot tie off the bull, I am talking 100 FPS differences and a low BC bullet
I guess my question is if you are not worried about velocity consistency why be concerned with case volume. I have a .223 load that is great for practicing technique, any fliers at 100 - 300 are due to my shooting technique. At 800 it would be all over the paper just on the vertical. On a calm day it would look like someone hung a polka dot tie off the bull, I am talking 100 FPS differences and a low BC bullet
Oh I see you are confusing curiosity with concern . Not worried really but when those CBC cases almost over flowed that peaked my curiosity on the case volume differences and what that would do performance wise . I don't remember which happened first The CBC 223 cases or the LC-14 cases but I also had that issue with my LC-14 cases not being able to be loaded to the same charge as ( what now is ) any of my other 308 cases . So again I measured and compared there case volumes . Again out of curiosity but there was a little concern with those because there was a full 2gr difference in charge weights with the velocities being where they should be respectively . The 43.5gr charge in the LC-12-LR cases was right up at 2700fps with no pressure signs while the 41.5gr charge in the LC-14 cases where under 2600fps while at the same time showing a pressure sign of sticky bolt lifts .
It would have been one thing if the LC-14 case velocities were at or faster then the other cases and showing pressure signs . How ever they were well below the velocities I was getting with the higher charge . So in my head I'm thinking 2gr less of a charge and well over 100fps slower . Those two things combined should indicate that load has a much lower peak pressure and yet I was still getting the sticky bolt . My curiosity went through the roof on that one .