Reloader's Nest Forum
Reloader's Nest Forum
Home | Profile | Register | Active Topics | Members | Private Messages | Search | FAQ
Username:
Password:
Save Password
Forgot your Password?

 All Forums
 Reloading General
 Measurement
 Brass variation - 338 LM
 New Topic  Reply to Topic
 Printer Friendly
Next Page
Author Previous Topic Topic Next Topic
Page: of 2

ten2six
Advanced Member



USA
3569 Posts

Posted - Mar 02 2012 :  13:10:59  Show Profile Send ten2six a Private Message  Reply with Quote
I've been busy on a couple projects this past year, so I'm rewarding myself with a new toy. I've got a .338 Lapua Mag rifle coming in a few weeks...finally get to play with the big boys.

Anyway, I have all the reloading materials and I'm trying to plan my test loads. I ordered three types of new brass: Lapua, Nosler, and Hornady. I've done the initial weight analysis and I'm at a loss for what I found. Here's the summary:

Lapua
  • 333.1 gr Avg
  • 1.9 gr SD
  • 5.6 gr ES

Nosler
  • 333.8 gr Avg
  • 0.2 gr SD
  • 0.9 gr ES

Hornady
  • 309.4 gr Avg
  • 1.8 gr SD
  • 6.8 gr ES


Each of these included 20 cases from the same lot/box. I've got thoughts about what to do, but I'd like to hear what some of you might consider next.

ten

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku

necchi
Advanced Member



USA
881 Posts

Posted - Mar 02 2012 :  14:00:06  Show Profile Send necchi a Private Message  Reply with Quote
While this chart may not show your listed brand cases, it's an example of the "why" to different case brass.
It's just a different alloy used by different manufacturers for what ever reason;




IIRC, I read someplace that there is a "minimum" percentage of brass required for sammi spec ??

Edited by - necchi on Mar 02 2012 14:02:39
Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Mar 02 2012 :  14:12:45  Show Profile Send ten2six a Private Message  Reply with Quote
Thanks necchi,

So what your saying is that Hornady must use a different alloy than the Lapua and Nosler?


"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku
Go to Top of Page

necchi
Advanced Member



USA
881 Posts

Posted - Mar 03 2012 :  01:07:38  Show Profile Send necchi a Private Message  Reply with Quote
Yup, nothing really to say it's better or worse,(beyond Lapua's stellar reputation) it's just different.

Never messed with Hornady brass much, some range pick-up, but nothing new. They do load most of their over the counter ammo pretty darn hot,,!
Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Mar 03 2012 :  01:22:33  Show Profile Send ten2six a Private Message  Reply with Quote
Very interesting stuff....must be one #%)) of a machine that can tell alloy composition with x-rays.

I am going to do case volumes on these 60 cases next, just to see if weight corresponds with volume and to use in QuickLoad. I'll post that soon.

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku
Go to Top of Page

mfim
Starting Member

USA
8 Posts

Posted - Mar 24 2012 :  10:29:21  Show Profile Send mfim a Private Message  Reply with Quote
This is very interesting stuff. I am retired toolmaker. The remington "low brass" would be the most ductile <soft, flows easily>
It has no silicon or chromium. Upon firing it would expand much quicker and spring back a less amount than other brass that contains silicon and chromium.The cases with silicon and chromium would expand slower and spring back a greater amount. On another note, the cases with more chromium and silicon would work harden much faster. On another note copper is a heavy metal and zinc a little lighter I beleive so you are correct on the weight variances. All the above goes back to not mixing brands of cases. Explains a lot of different little things that has happened in the last 25 years of my reloading. Keep up the good work. Very interesting thread. Don



don
Go to Top of Page

Bobo7mmmag
Advanced Member

2612 Posts

Posted - Mar 31 2012 :  14:44:13  Show Profile Send Bobo7mmmag a Private Message  Reply with Quote
Very good answer "mfim".
Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Mar 31 2012 :  19:58:31  Show Profile Send ten2six a Private Message  Reply with Quote
OK...spent the rainy morning doing case capacities for the .338 LM cases...

Here's the summary. I measured 5 from each group.

Hornady - fired cases: 116.1 gr of water; .9 gr ES; SD = .33 gr

HSM brass - fired cases: 115.6 gr of water; .7 gr ES; SD = .27 gr

Nosler - sized cases: 113.4 gr of water; .5 gr ES; SD = .23 gr

Lapua - not sized: 113.2 gr of water; .4 gr ES; SD = .14 gr

Hornady - not sized: 116.0 gr of water; .8 gr ES; SD = .28 gr

So what does it mean? First, QuickLOAD defaults case capacity for .338 LM to 108 grs, so much lower (5 - 8 gr) than the real world. When you adjust that in QuickLOAD the predictions start to look like Sierra loading data.

Lapua and Nosler brass were identical when comparing weight to volume. Hornady brass weighs less, but has more case volume. The ratios for Lapua and Nosler were both 2.94, Hornady was 2.66.

So anyone want to comment on this??? I assume the higher case volumes with the Hornady brass means pressures would be lower (all else being equal). Good, bad, no different?????

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku
Go to Top of Page

woods
Advanced Member

USA
2022 Posts

Posted - Apr 01 2012 :  09:42:27  Show Profile Send woods a Private Message  Reply with Quote
Hey ten

The most interesting dimension to me would be the neck thickness variation. That will determine more about it's ability to enhance accuracy. It's all about bullet grip and runout

Nosler is supposed to be weight sorted but twice I got a bad box of Noslers where the the brass varied from .017" on the thick side to .009" on the thin side! It didn't matter if they all weighed the same.

Weatherby supposedly uses Lapua brass to their Weatherby's stringent specs and that is part of the reason Weatherby's have any accuracy at all. I only reload for one 300 Wtby and the brass neck thickness consistancy was excellent on the Wtby cases.

The amount of internal volume will have little to do with pressures. The pressure from the powder in the chamber is so much larger that the brass ductility is a grain of sand on the beach by comparison. Think about this, you can easily size a brass case but if there were such a thing, how easy would it be to size a steel chamber. Pressure on the brass is like a truck blowing through a fog bank. No hindrance.


When someone shares something of value with you and you benefit from it, you have a moral obligation to share it with others.


Edited by - woods on Apr 01 2012 09:43:50
Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Apr 01 2012 :  12:21:15  Show Profile Send ten2six a Private Message  Reply with Quote
Hey woods,

I agree that the chamber will always be the limiting factor for pressure...cases can't expand (or at least you don't want them to..) any more than that.

I was wondering more that if two brands of brass have different amounts of material, they will effectively displace the chamber volume based on that. In an extreme example, one case has half the internal volume of the second. A safe powder charge in the second would not likely be safe in the first...correct?

QuickLOAD allows...actually encourages...actual case volume measurements. I took fired, sized and un-sized volumes just to make sure nothing stood apart. QuickLOAD defaulted the .338 LM case volume as 108.0 gr of water. I changed that to the smallest (most conservative) measurement I took...~113 gr of water. The load predictions changed drastically. Before, with the small volume default, MAX loads were 3 - 5 gr lower than book loads (Sierra, Hornady, Lapua, Lyman, etc..). Now that I've changed to the 'actual' volume, the predictions QuickLOAD is showing actually are within a grain or two of the load manual loads.

Interestingly, changing case volumes from 113 to 115 in QL ups the Max powder charge, but I think it's better to use the most conservative real measure and work up from there.

Let me know what you think of my logic (or lack of). Thanks.

ten

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku
Go to Top of Page

woods
Advanced Member

USA
2022 Posts

Posted - Apr 01 2012 :  14:03:50  Show Profile Send woods a Private Message  Reply with Quote
Well I think weight would be more of an indication of the combustion chamber size. That is defining the combustion chamber as the amount of volume of the chamber minus the volume of the brass.

IOW you could have a case that weighed 310 gr and had a case capacity of 120 gr and another case that weighed 300 gr and had a case capacity of 110 gr. That is on new brass. Even though the heavier one has more brass and should have less capacity, one was just manufactured to a smaller dimension than the other.

Now if you are measuring the weight and case capacity of a fired unsized case then weight and capacity should have a reverse correlation.

In any scenario if the brass is not fire formed to the chamber then the brass would put up little resistance to expanding to the chamber and would not effect pressure. That is what I was thinking of.

Now on fired brass then the case with less weight should also have more case capacity and vice versa.

But what about the consistancy of neck thickness. Do you have a ball micrometer? Case neck thickness consistancy would be the number one factor in deciding which brass to buy for me.


When someone shares something of value with you and you benefit from it, you have a moral obligation to share it with others.


Edited by - woods on Apr 01 2012 14:12:23
Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Apr 01 2012 :  16:47:48  Show Profile Send ten2six a Private Message  Reply with Quote
I agree, weight of brass gives an indication of what your combustion chamber size will be. The brass is flexible, but not compressible, so volume occupied by the brass reduces the effective combustion chamber size. More weight means less combustion chamber.

The data above does show the predicted inverse relationship. The Nosler and Lapua brass had identical weights and case capacities. The Hornady brass, on average, weighed 24 grains less, and had almost 3 gr more case capacity. The fired brass came from factory ammo. Weights on those cases also follow suit...Hornady weigh less, HSM more..but not quite what Lapua and Nosler new brass does.

Don't get me wrong...the Hornady factory ammo (250 gr Match BTHP) was super accurate. I had under 2" group at 300 yards with no rest. HSM had 300 gr Berger hybrids and the group size was closer to 3". The rifle is capable of better. Test target that came with the rifle had a 10 shot, 300 yard, 7/8" group...I wish I could be so good.

I haven't started looking at the necks yet. I do have a good ball micrometer...it might even be older than me.... It came from a local paper factory that went belly up back in the 80's. I've already bought 3 brands of new brass....Lapua, Hornady, and Nosler. I will look at necks next...want to know as much as I can about consistency...both inside and out. I'll post more as I continue.


"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku

Edited by - ten2six on Apr 02 2012 11:42:53
Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Apr 17 2012 :  22:45:23  Show Profile Send ten2six a Private Message  Reply with Quote
quote:
Originally posted by woods

Hey ten

The most interesting dimension to me would be the neck thickness variation. That will determine more about it's ability to enhance accuracy. It's all about bullet grip and runout

Nosler is supposed to be weight sorted but twice I got a bad box of Noslers where the the brass varied from .017" on the thick side to .009" on the thin side! It didn't matter if they all weighed the same.

Taxes are done......

Had time today to check neck wall thickness uniformity. Used a Sinclair neck sorting tool with digital dial gauge. Indexed and rotated each case twice. Variation listed is MAX minus MIN, so describes how uniform the neck walls are. I measured 10 cases for all for types of brass, so I'll list 'Average', 'ES', and 'SD'. If anyone wants actual neck thickness, just ask, I have that too.



Results, in no particular order...

Hornady cases...
  • 0.0015" Average variaton
  • .0040" ES
  • 0.0012 SD

HSM cases...
  • 0.0015" Average variation
  • 0.0025" ES
  • 0.0007" SD

Lapua cases...
  • 0.0016" Average variation
  • 0.0025" ES
  • 0.0008" SD

Nosler cases...
  • 0.0015" Average variation
  • 0.0025" ES
  • 0.0008" SD


My take away is that all brands have very uniform neck wall thicknesses.

The real question, though, is what would you do next woods???

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku

Edited by - ten2six on Apr 17 2012 22:46:11
Go to Top of Page

mhiltz
Advanced Member

USA
645 Posts

Posted - Apr 21 2012 :  02:31:05  Show Profile Send mhiltz a Private Message  Reply with Quote
Hello Ten,

Very interesting thread here. A while back I was looking at this same issue. I had just bought some new Win 308 brass, and there was a huge weight difference in that lot of brass. I don't remember all of the details right now, but I know I load the 308 pretty hot. I also use QL, and was wondering if it was accurate in the H20 case capacity vs pressure department. So I was using my Chrony to test the MV, and noticed that what QL was predicting was almost exactly what I was coming up with for my velocities over the Chrony. So I deciced that it is pretty close to right on its pressures. If I loaded the heavier cases with the same hot load that I use on the lesser weighted cases, I would gain in MV, so you gotta figure that the pressure went up. I will dig around for my data on that, and will definitely let you know.

I do remember that 46.0 gr of IMR4064 with the lower average weight cases and 150gr bullets were running right around 2800fps. While with the heavier ones it only took 45.1gr of powder to shoot those 150gr bullets 2800fps. That is why I think folks get such a variation of velocity when shooting over a Chrony, they don't weigh their cases.
I used 56.0 gr H20 cap. and 54.5. So I got practically the same MV using .9gr of powder less with the heavier cases. Interesting stuff here!


"It's better to have it and not need it than to need it and not have it" Captain Call Texas Ranger

Go to Top of Page

mhiltz
Advanced Member

USA
645 Posts

Posted - Apr 21 2012 :  02:34:41  Show Profile Send mhiltz a Private Message  Reply with Quote
By the way, Congrats on the new rifle!!!

"It's better to have it and not need it than to need it and not have it" Captain Call Texas Ranger

Go to Top of Page

ten2six
Advanced Member



USA
3569 Posts

Posted - Apr 21 2012 :  12:59:48  Show Profile Send ten2six a Private Message  Reply with Quote
Thanks mhiltz....

I think you're right about case weight and velocity variation. I'd be interested in hearing more about your .308 data. This has been an eye opener, especially when working with QL. When I started I was just trying to make some sense out of load recipes that were all over the board. Now I'll be measuring case weights and case capacities every time I work up a load.

"Chances are, when we meet intelligent life forms in outer space, they're going to be descended from predators."
- Michio Kaku
Go to Top of Page
Page: of 2 Previous Topic Topic Next Topic  
Next Page
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
Reloader's Nest Forum © 2013 ReloadersNest Go To Top Of Page
This page was generated in 0.16 seconds. Powered By: Snitz Forums 2000 Version 3.4.06