Case Volume Question

[MAHLMAN]

I recently got some processed brass and there are two case manufacturers in there. While reloading I kept getting an alarm on the powder sensor. I would stop and weigh the powder and it was always right where it was supposed to be. After some time it dawned on me to weigh the case after seeing a higher level of powder in the case, while the powder weight was correct when checked. So the one brand is right at 9gr heavier and this results in a visibly smaller amount of empty case space after the powder drop.

So my question is with the right powder charge in these heavier cases does the smaller amount of remaining empty volume pose a problem on shooting from too much pressure?

.223 62gr bullets of various types and 24gr AR + is the load.

 

[TheOfficeT-Rex]

Far to many variables there for us to be definitive.

Which bullet, how close to max you are, any powder compression, your rifle's chamber, etc etc all play a roll and unless you test it for yourself we're just here in the cheap seats with beer speculating.

 

[Near miss]

Whose cases you got

 

[918v]

Yes, heavier cases have less internal volume and this will increase pressure. That being said, if you are loading intelligently and well below max, then you will not create a dangerous situation.

 

[MAHLMAN]

Cases are Wolf and CBC. Bullets are 62gr Trophy Bonded Bear Claw, 62 gr Hornady spitzer boat tail and 62gr Hornady FMJ boat tail. I am 1.5gr below recommended Shooters World max on this bullet weight. CBC is the heavier case. No powder compression. Chambers are all 5.56 Nato in AR-15's.

 

[M4orturnate]

So a friend of mine was doing some experimenting with lc, lapua, and starline. I forget wich cases it was but 2 had vastly different total weight but the same internal capacity on once fired brass. All im saying is weighing brass is basically pointless. It doesnt tell you anything about internal capacity.

 

[Molon]

Depending upon variables, the variations in case weight/volume can easily result in increases of muzzle velocity of 85 FPS or more, with an attendant increase in chamber pressure. If already at the maximum average pressure, using heavier cases certainly poses the risk of creating over-pressures loads.

….

 

[MAHLMAN]

There is a visible difference in how much of the case is filed and the CBC brass sets off the powder check device on the Dillon RL750. The case weight difference I am assuming means the CBC brass has less volume since that weight difference has to be in brass volume. The OD of these cases guage just fine.

 

[918v]

So a friend of mine was doing some experimenting with lc, lapua, and starline. I forget wich cases it was but 2 had vastly different total weight but the same internal capacity on once fired brass. All im saying is weighing brass is basically pointless. It doesnt tell you anything about internal capacity.

Bullshit

 

[M4orturnate]

Bullshit

I take it you sort your cases by weight haha

 

[918v]

I take it you sort your cases by weight haha

No, but there is a case weight and volume difference between various brands of brass. You can’t mindlessly use data without considering the case it was developed in.

 

[M4orturnate]

No, but there is a case weight and volume difference between various brands of brass. You can’t mindlessly use data without considering the case it was developed in.

No shit. Ill im saying is you cant judge internal volume by case weight. Look at molons graph above. Then way a piece of lapua and lc. Youll have a big difference in total weight and a .1g in capacity.

 

[918v]

No you won’t. Lapua made 2 different 223 cases, one of which was 10% heavier. That case has less volume and produces more velocity with a given charge weight.

The other is similar in weight and internal capacity to LC and produces similar velocities.

 

[Molon]

Look at molons graph above. Then way a piece of lapua and lc. Youll have a big difference in total weight and a .1g in capacity.

Take a better look at what I posted. There was a 1.2 grain of H2O difference in case capacity (not 0.1 grain) between the Lake City and Lapua Standard brass which had the big difference in weight.
...

 

[Near miss]

I measured a shot CBC few weeks ago and it showed 30.47gr. I already sized all of them, just wanted to get the ballpark they are in.

 

[M4orturnate]

Take a better look at what I posted. There was a 1.2 grain of H2O difference in case capacity (not 0.1 grain) between the Lake City and Lapua Standard brass which had the big difference in weight.
...

The very bottom in blue. Lapua match and unknown lot of lc. 30.3 and 30.4. Now what is the empty weight of the cases if you have that info? All im saying is you cant tell internal volume from weighing cases. Of course if one brand is 5g heavier there is less volume but if you have 5 cases from the same lot weighing them will tell you zero about internal volume. Also not all brass is equal. Some heavier cases have surprising volume comparatively.

 

[Haney]

Case weight is not a great way to guess volume . Where the weight of the brass comes from makes a difference , like walls, base/web , etc . .

 

[straightshooter1]

There is a visible difference in how much of the case is filed and the CBC brass sets off the powder check device on the Dillon RL750. The case weight difference I am assuming means the CBC brass has less volume since that weight difference has to be in brass volume. The OD of these cases guage just fine.

Think about it, if the cases wall is thicker than another making the case heavier (give all other specs are equal), it's going to have less volume. This is why when using various brass, it's best to measure the case volume of a particular lot so one can adjust powder accordingly. . . though typically, because of this issue, it's not a good idea to mix headstamps when reloading.

 

[MAHLMAN]

Think about it, if the cases wall is thicker than another making the case heavier (give all other specs are equal), it's going to have less volume. This is why when using various brass, it's best to measure the case volume of a particular lot so one can adjust powder accordingly. . . though typically, because of this issue, it's not a good idea to mix headstamps when reloading.

Oh I agree with that but what I was wanting is a general indication as to safety. I don't load to bleeding edge velocity and don't go for 2" at 600 yards either. I have some picked out separate and guess I will shoot a few and look for signs of over pressure. Now I have never seen reloading data based on specific case volume nor do I have any way to measure pressure except to look at fired cases. I can measure velocity and weight only.

 

[918v]

But you have seen data based on case brand. It doesn’t take much effort to find out how much those cases weigh. Hodgdon, for example, uses Winchester brass for their data. Those cases weigh 92-94 grains. So if your heavy cases are 9 grains heavier you can expect more pressure. People telling you otherwise are wrong. You can’t hide that much brass on a 223 case where it doesn’t intrude on case volume.

 

[straightshooter1]

Oh I agree with that but what I was wanting is a general indication as to safety. I don't load to bleeding edge velocity and don't go for 2" at 600 yards either. I have some picked out separate and guess I will shoot a few and look for signs of over pressure. Now I have never seen reloading data based on specific case volume nor do I have any way to measure pressure except to look at fired cases. I can measure velocity and weight only.

I use the app QuickLoad to help me with such an issue and keeps me within safe limits. Otherwise, I suppose the best way is to measure volumes and use a percentage adjustment for the powder in cases that are lower in volume. It's still just not a good idea to mix case heads, especially if there's substantial variation in volumes.

 

[MAHLMAN]

But you have seen data based on case brand. It doesn’t take much effort to find out how much those cases weigh. Hodgdon, for example, uses Winchester brass for their data. Those cases weigh 92-94 grains. So if your heavy cases are 9 grains heavier you can expect more pressure. People telling you otherwise are wrong. You can’t hide that much brass on a 223 case where it doesn’t intrude on case volume.

I agree 100% on case volume. It would be impossible for the brass to accumulate anywhere but inside the case one way or another.

I use the app QuickLoad to help me with such an issue and keeps me within safe limits. Otherwise, I suppose the best way is to measure volumes and use a percentage adjustment for the powder in cases that are lower in volume. It's still just not a good idea to mix case heads, especially if there's substantial variation in volumes.

OK I think that software sounds like a good idea. Has it covered all the brass and powder you have encountered so far?

 

[straightshooter1]

I agree 100% on case volume. It would be impossible for the brass to accumulate anywhere but inside the case one way or another.

OK I think that software sounds like a good idea. Has it covered all the brass and powder you have encountered so far?

QuickLoad's powder data base is pretty extensive, though as you might expect, it takes a little time for that data base to be updated with newer powders. As for brass volumes, it starts with a default volume within SAAMI spec for the particular cartridge and it's up to the user to enter the case volume, which is usually different than the default volume (and note, the volume to use in these apps are for fired cases, not virgin or sized cases).

Besides QuickLoad, which you have to pay for, there's Gordons Reloading Tool that is for free and very similar to QuickLoad. But its database is not quite as extensive as QuickLoad's, though it's a work in progress. While GRT's database isn't as extensive, I think it can still be useful to you and you can play around with it to get an idea how to use QuickLoad if you happen to choose QL.

Here's what QL looks like and note the Maximum Case Capacity in the middle two columns where you enter what your average case capacity goes:

Here what GRT's looks like and you do the same kind of entry for your caluculations: