Question Regarding Case Capacity

Printable View

02-06-2016, 10:35 AM
Silvercrow1

Question Regarding Case Capacity

In my quest to get the best loads possible (for me, anyway) I am looking at case capacity for my .223 Rem reloads. There are a couple of websites that give case capacities re: volume of water. I just bought 100 Lapua Match cases- empty weight they are significantly heavier than the LC 07, LC 11 and .FC. I have been using. I realize internal capacity is what matters regarding weight. Some postings on the internet indicate that Lapua Match cases had less vol. using water weight measure- but I intend to weigh them myself.

SO logic tells me the less internal capacity, the more pressure, correct? So I'd need to reduce loads somewhat to attain the same results when going to a case with lesser internal capacity?

I've read here and elsewhere that when using military brass (thicker walls, less internal space) to reduce loads by 10%. I generally do not load to max weights anyway.

IS THERE A FORMULA available to tell how much reduction is needed to maintain equal pressures when various cases? In a 2007 thread here one of our members attached a link for just this thing...but the link did not work. Maybe I'm not searching with the proper words- but I am finding nothing. Not trying to be lazy- just more efficient in re-working loads. For instance, I use 25.1 GN Win. 748 behind a 50 Gn. Vmax bullet in my LC11 cases and get consistently great (less than 1/3") groups. If I do the 10% reduction thing, I'd have to start back at 2.3 / 2.4 grains?

Any help would be appreciated. THANKS!

Brian
02-06-2016, 02:56 PM
Jamie

This isn't what you really want to here but there is no formula. Just the standard rules of reloading, if you change a component , start over. Go ahead and drop the 2 grains and work back up. The loads almost certainly wouldn't shoot the same anyway and you will have to find the sweet spot using that brass.
02-06-2016, 05:28 PM
bigedp51

I buy once fired Lake City cases because the base of the case is harder and the flash hole web is thicker and the cases last longer. The quality of these Lake City cases in my opinion is very good and I buy then at a fraction of the cost of Lapua brass.

http://i122.photobucket.com/albums/o...ps3f8bb2c9.jpg

http://i122.photobucket.com/albums/o...ps3566d29a.jpg

CatShooter solved an argument at AccurateShooter.com about brass hardness and quality of the .223/5.56 brass.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests
http://bulletin.accurateshooter.com/...ardness-tests/

Bottom line the vast majority of .223/5.56 cases are very close in case capacity, with Lake City having the most capacity and the hardest brass in the base web area. Meaning Lake City cases are built Ford Truck Tough.

http://i122.photobucket.com/albums/o...ps7570e6b0.jpg

http://i122.photobucket.com/albums/o...ps8d54ad66.jpg

Below Lake City and commercial contract 5.56 ammunition is thicker at the flash hole web making the base stronger and far less primer pocket stretching.

http://i122.photobucket.com/albums/o...psbp4r0zok.jpg
02-06-2016, 07:16 PM
Texas10

I've been using a lot of American Eagle brass I've kept from shooting factory ammo in my 223. For the most part, those Federal (FC) brass has been by far the most consistent by weight compared to my Hornaday and Winchester brass. One of my current loading blocks consistes of 100 FC brass all weighing between 92.0 and 92.5 grains. My newly purchased 100 pcs of Winchester 223 brass is barely within 2 grains and I had to toss a few due to neck wall defects.
I have not performed a water capacity test yet, but plan to. Not sure it's even necessary on such a small case.

One thing I noticed with the most recent American Eagle brass I have as compared to year old brass is the flash hole placement. None of my most recent AE brass has flash holes that are centered in the primer cup. It's all off center by at lease a little, to as much as 3/4 hole diameter off center.

Older brass is much more consistent, and Hornaday brass seems to be very consistent, albeit a bit soft.

Not sure how much this effects powder ignition in a small case, but it's the reason I'm trying to buy higher quality brass. Someday I may have to bite the bullet and buy Lapua.
02-06-2016, 08:05 PM
Silvercrow1

ALL good information- thanks for those responses thus far!

@Texas 10; My FC brass has two different headstamps- one just "FC" in a thinner font; the other has a "dot" before and after the FC, centered ".FC." (but the dots are centered). That brass has been good to me- finally showing wear after 7 reloadings (so 8 "shots" including when it was new).

My LC brass was bought from a guy here on this forum, he originally got it from Scharf (I think I speled that right). Anyway, its marked mostly "07" and about 20 % marked "11". Its good but in weighing it, the "11" is consistent- the "07" varies but up to 1 grain.

I'm just now delving into capacity- I've been reloading for just over 3 years and have had great success in developing loads for my .223 and .308. But my .223 is starting to wear and in loading the LC brass now as the FC is wearing out, I noted fluctuations in group size and consistency.

@ Jamie- yeah- no shortcuts...I'll 'start over'. I love this stuff anyway and it keeps me thinking and learning- which I NEVER want to stop doing.

Brian
02-12-2016, 02:32 PM
darkker

BigEd has some good info posted there.
I called the domestic makers a couple of years ago now. What they told me was that they are all built to the same standard, simply stamped differently.
Somewhere that currently escapes me, I *THINK* it came from a friend that used to run the Pic arsenal testing... Anyway, back when, the standard variance on any given production line was surprisingly large. So weighing may indicate volume, but only from a single lot, on a single run, from a single set of machines in their current state of wear. Accurate shooter also recently had an alloy test, and not all are the same.

Also keep in mind that Federal stamped brass usually has VERY soft brass, down to the case heads. This is "nice" for single fired ammo accuracy, as it expands and seals the chamber uniformly and quickly. It isn't nice however when it comes to multiple reloads, heads love to seperate.
02-12-2016, 06:10 PM
rovert

There is a formula, sort of. It's just not something you're going to punch out on your calculator. Quickload can run case capacity vs pressure calculations. It is NOT, however, a substitute for working up loads for your rifle. It can give you an idea of where you are going to achieve the same pressure with a different case capacity. You need to know the case capacity (gr H2O) of both the cases for your established load and that of the new cases.
02-12-2016, 06:20 PM
LongRange

Quote:

Originally Posted by rovert

There is a formula, sort of. It's just not something you're going to punch out on your calculator. Quickload can run case capacity vs pressure calculations. It is NOT, however, a substitute for working up loads for your rifle. It can give you an idea of where you are going to achieve the same pressure with a different case capacity. You need to know the case capacity (gr H2O) of both the cases for your established load and that of the new cases.

this will work as long as you have shot over a chrony and verified that the velocities match...if not the Ba needs to be adjusted in QL to match your actual chrony velocities and this is where a good chrony is needed.
02-12-2016, 06:40 PM
darkker

Quote:

Originally Posted by LongRange

this will work as long as you have shot over a chrony and verified that the velocities match...if not the Ba needs to be adjusted in QL to match your actual chrony velocities and this is where a good chrony is needed.

+1

QL is great for the stuff coming out of Groupe SNPE, and some Thales powder. GD and Hodgy won't tell Hartmut anything. So depending upon where the lot variance falls, QL is a neat little toy.
The chrono is the pratical reference for pressure.
02-13-2016, 11:54 PM
Silvercrow1

WHEW-a lot to learn. I'll admit I've heard of Quickload but have never used it. I've weighed the cases, primed, empty and H2O filled (I watched the Miniscus!) and I was surprised at some of the results. The Norma brass is baffling; the only brass heavier that I have is the Lapua BUT the H2O capacity for the Norma is...more?? I picked 3 random cases from my box of 50 new Norma, averaged weight primed / empty of 95.1 Gn, average weight, H2O filled 126.2 Gn net water weight 31.1 Gn. The Federal, LC 07, LC 11, and Lapua cases I have ALL show H2O capacity congruent with their empty weights; i.e. heavier cases = less capacity. Maybe I'm doing something wrong?

I guess it could be case brass components are such they are heavier? I'm using the same primers to weigh also. Dunno...

Brian
02-14-2016, 08:46 AM
LongRange

you should be putting a dry case with the primer pocket plugged on your scale then zero the scale with the case on it then add your water and that is the number you are most concerned with...and old primer works to plug the pocket but its slow and adds extra steps...21st century shooting supply makes primer pocket plugs...

http://www.21stcenturyshooting.com/P...cket_Plugs.php
02-14-2016, 11:16 AM
Dewey7271

LR gave you good advice as have the others.
Next is checking capacity on fired cases. Do the same as LR mentioned but with fired cases this time. Reamers and rifle chambers vary. Knowing the fired case capacity plus the chrono readings gives more specifics thus more usable relevant info.
02-15-2016, 11:01 PM
Silvercrow1

Quote:

Originally Posted by LongRange

you should be putting a dry case with the primer pocket plugged on your scale then zero the scale with the case on it then add your water and that is the number you are most concerned with...and old primer works to plug the pocket but its slow and adds extra steps...21st century shooting supply makes primer pocket plugs...

http://www.21stcenturyshooting.com/P...cket_Plugs.php

Thanks for the info on the primer plugs. I did weigh with primers in. Dry first and then with H2O. Sorry if that was not clear. The plugs would certainly be more convenient. Thanks

Brian
02-15-2016, 11:03 PM
Silvercrow1

Quote:

Originally Posted by Dewey7271

LR gave you good advice as have the others.
Next is checking capacity on fired cases. Do the same as LR mentioned but with fired cases this time. Reamers and rifle chambers vary. Knowing the fired case capacity plus the chrono readings gives more specifics thus more usable relevant info.

Thanks to you also. I'm looking into a chrono- meanwhile I think there is a guy at our club that would let me borrow his.

Recommendations on a good, reasonable priced chrono? I can afford around $100.00 but not 200...

Brian
02-16-2016, 08:07 AM
Texas10

Check out this link regarding chronograph comparison test;

http://www.savageshooters.com/showth...e-did-I-see-it
02-16-2016, 03:57 PM
bigedp51

Quote:

Originally Posted by Silvercrow1

In my quest to get the best loads possible (for me, anyway) I am looking at case capacity for my .223 Rem reloads. There are a couple of websites that give case capacities re: volume of water. I just bought 100 Lapua Match cases- empty weight they are significantly heavier than the LC 07, LC 11 and .FC. I have been using. I realize internal capacity is what matters regarding weight. Some postings on the internet indicate that Lapua Match cases had less vol. using water weight measure- but I intend to weigh them myself.

SO logic tells me the less internal capacity, the more pressure, correct? So I'd need to reduce loads somewhat to attain the same results when going to a case with lesser internal capacity?

I've read here and elsewhere that when using military brass (thicker walls, less internal space) to reduce loads by 10%. I generally do not load to max weights anyway.

IS THERE A FORMULA available to tell how much reduction is needed to maintain equal pressures when various cases? In a 2007 thread here one of our members attached a link for just this thing...but the link did not work. Maybe I'm not searching with the proper words- but I am finding nothing. Not trying to be lazy- just more efficient in re-working loads. For instance, I use 25.1 GN Win. 748 behind a 50 Gn. Vmax bullet in my LC11 cases and get consistently great (less than 1/3") groups. If I do the 10% reduction thing, I'd have to start back at 2.3 / 2.4 grains?

Any help would be appreciated. THANKS!

Brian

Silvercrow1

American military 5.56 cases made at Lake City are not made thicker, they are made harder in the base. If LC 5.56 cases were made thicker like LC 7.62 cases it would cut down too much on their internal capacity. The chart I posted from AccurateShooter.com shows that the vast majority of .223/5.56 cases are very close in case cpacity.

If you look at the case weight chart you will see Lapua cases only varied 1.2 grains in weight, and the Winchester cases varied 6.5 grains in weight. "BUT" both the Lapua and Winchester cases averaged 30.1 of case capacity, meaning the Lapua cases are more consistent in weight and internal volume and thus equaling better quality and accuracy.

The quickload information below was made up for loading my AR15 rifles "before" I got my chronograph and are "ballpark" guesstimates. Meaning the burn rate in Quickload was not adjusted using a chronograph so the pressures and velocities will not be corrected by matching velocities. The charts were made up to see how much the pressure and velocities would vary between cases with a internal volume of 30.6 and 28.0 grains of H2O.

Below a Lake City case with 30.6 grains H2O capacity, 25 grains of H335 powder and a Hornady 55 grain FMJ bullet.

http://i122.photobucket.com/albums/o...psf81bb4cc.jpg

Below the same exact load using a case with 28.0 grains H2O capacity and a increase of 6,000 psi in chamber pressure.

http://i122.photobucket.com/albums/o...ps26698a67.jpg

The purpose of the charts was to see how much pressure and velocity variance I would have using mixed brass at the extreme ends of capacity with my AR carbine. With the Lake City, Federal and Remington cases I'm using with my load of 25 grains of H335 the case capacity only varies less than 1/2 a grain in capacity and good enough for practice ammunition with my AR15 carbine.

Bottom line, I also have a Stevens 200 .223 bolt action and do not use mixed brass and use brass from the same manufacture for better uniformity and accuracy. You are always better off using uniform brass and if you try using mix brass your group sizes will increase. Uniformity goes hand in hand with accuracy and I'm happy with three inch groups with my AR15 carbine with "mixed" brass and happy with the 3/4 to 1/2 inch groups with my Stevens 200 using uniform brass from one manufacture.

As a side note the vast majority of .223/5.56 brass I buy is once fired Lake City brass, and for the "quality" and price it can not be beat. And when weight sorted and uniformed it is very uniform and far cheaper than Lapua. I'm 65, have chronologically gifted eyesight and drink too much coffee and and this is just a opinion of a old fart.
02-17-2016, 12:39 PM
Hair_Boxers

Quote:

Originally Posted by Silvercrow1

Thanks to you also. I'm looking into a chrono- meanwhile I think there is a guy at our club that would let me borrow his.

Recommendations on a good, reasonable priced chrono? I can afford around $100.00 but not 200...

Brian

Silvercrow - If you can't borrow a chrono locally, we may be able to figure out a Gentlemen's agreement for a way to let you borrow my MagnetoSpeed Sporter for a week or two.

I love it and don't use it every weekend so if I can help someone out until they can get their own I'd like to see if I can do that.
02-18-2016, 02:46 PM
Silvercrow1

Quote:

Originally Posted by Hair_Boxers

Silvercrow - If you can't borrow a chrono locally, we may be able to figure out a Gentlemen's agreement for a way to let you borrow my MagnetoSpeed Sporter for a week or two.

I love it and don't use it every weekend so if I can help someone out until they can get their own I'd like to see if I can do that.

WOW! You know, I've said it before and I'll say it again; this is THE friendliest and helpful site concerning guns (or guitars- my other passion) bar-none.

Hair_Boxers I just started a new job and am in training- should settle down in a week or two. IOW I won't be shooting much for about 1-2 weeks. But I'd love to make a deal with you for rent or whatever- understanding full responsibility, etc. THANKS! I'll PM you over the next day or so.

Brian
02-18-2016, 02:47 PM
Silvercrow1

Quote:

Originally Posted by bigedp51

Silvercrow1

American military 5.56 cases made at Lake City are not made thicker, they are made harder in the base. If LC 5.56 cases were made thicker like LC 7.62 cases it would cut down too much on their internal capacity. The chart I posted from AccurateShooter.com shows that the vast majority of .223/5.56 cases are very close in case cpacity.

If you look at the case weight chart you will see Lapua cases only varied 1.2 grains in weight, and the Winchester cases varied 6.5 grains in weight. "BUT" both the Lapua and Winchester cases averaged 30.1 of case capacity, meaning the Lapua cases are more consistent in weight and internal volume and thus equaling better quality and accuracy.

The quickload information below was made up for loading my AR15 rifles "before" I got my chronograph and are "ballpark" guesstimates. Meaning the burn rate in Quickload was not adjusted using a chronograph so the pressures and velocities will not be corrected by matching velocities. The charts were made up to see how much the pressure and velocities would vary between cases with a internal volume of 30.6 and 28.0 grains of H2O.

Below a Lake City case with 30.6 grains H2O capacity, 25 grains of H335 powder and a Hornady 55 grain FMJ bullet.

http://i122.photobucket.com/albums/o...psf81bb4cc.jpg

Below the same exact load using a case with 28.0 grains H2O capacity and a increase of 6,000 psi in chamber pressure.

http://i122.photobucket.com/albums/o...ps26698a67.jpg

The purpose of the charts was to see how much pressure and velocity variance I would have using mixed brass at the extreme ends of capacity with my AR carbine. With the Lake City, Federal and Remington cases I'm using with my load of 25 grains of H335 the case capacity only varies less than 1/2 a grain in capacity and good enough for practice ammunition with my AR15 carbine.

Bottom line, I also have a Stevens 200 .223 bolt action and do not use mixed brass and use brass from the same manufacture for better uniformity and accuracy. You are always better off using uniform brass and if you try using mix brass your group sizes will increase. Uniformity goes hand in hand with accuracy and I'm happy with three inch groups with my AR15 carbine with "mixed" brass and happy with the 3/4 to 1/2 inch groups with my Stevens 200 using uniform brass from one manufacture.

As a side note the vast majority of .223/5.56 brass I buy is once fired Lake City brass, and for the "quality" and price it can not be beat. And when weight sorted and uniformed it is very uniform and far cheaper than Lapua. I'm 65, have chronologically gifted eyesight and drink too much coffee and and this is just a opinion of a old fart.

THANKS! From one "OLD FART" to another! Very interesting and insightful- pardon the pun! We're never too old to learn and improve!

Brian