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Variance in case capacity between brands

jambau

Sergeant
Full Member
Minuteman
Sep 2, 2010
399
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PA
Curious if anyone can make a generalization as to which brands of cases tend to have more capacity. I've seen a difference of about 2.5 grains between three different brands of 338 LM cases with a given powder. I've had instances where load development was halted by case capacity. Not big on compressed loads.
 
I think you are going about this the wrong way. Cases need to be consistent. If one brand has a bit more volume, that's all well and good, but are those cases, now lighter and thinner, consistent? If not, it matters little.

Next, case volume limiting load development makes no sense, unless you've got the fastest possible powder and still can't get enough in the case. for example, you can't get enough H1000 into a .308 case to launch 175gr bullets at a reasonable velocity. What to do? Use a faster powder. Loading subsonics? Now the case is way too big, so we need a bulky powder that still generates lower pressures, enter Trailboss.

Your problem is not case volume, it's powder/bullet selection. I realize that especially now, you may have 10 lbs of X powder and want to use it. OK, step up to the next heavier bullet. If that does not solve teh problem then the powder is likely to simply be unsuitable to the case. 10# of Retumbo and a lot of 6.5 Creedmore brass, bullets and primers does not make usable ammo.

What powder/bullet combination are you trying to use in the 338LM?
 
Would you mix projectile weights and brands?
Pick a brand, and preferably a lot#
Keep cases with each other with a known number of firings.

What you are doing is leading to a potential very bad day at worst and constant frustration at best.

Do you load other rifle calibers?
 
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So before I get piled on: I already have a great load for this round (posted in the Depot). I full understand all the aspects of consistency in reloading. I was asking a general question. Here's why: Currently I'm loading 98 gr. of RL33 under a 285 gr. ELDM in well prepped (consistent) Hornady cases. This is about all the powder I'm going to get into the case without a lot of compression. I wanted to play around with the 250's and many manuals are listing up to 103gr. with this powder for this weight bullet. I thought switching to another case might afford me that little extra room.
 
In my experience, i find that Lapua and Peterson have less case capacity than Hornady and Winchester, for example. I also find a bit more consistency when water weighing internal capacities on both a 10 & 20 average per case make on the former 2 brands as well.
 
Ok, so you're out of room for more powder - but how are your speeds?
 
PPU 338LM

 
Ok, so you're out of room for more powder - but how are your speeds?
Thanks for the reply. I have no idea about the speed as I haven't loaded them (the 250's) yet. I would have liked to start around 99.0 gr and work up but case capacity is already maxed out. I don't have a problem switching powders. I was just looking to use my current load as a starting point with the current powder.
 
Lapua 338LM

 
Thanks for the reply. I have no idea about the speed as I haven't loaded them (the 250's) yet. I would have liked to start around 99.0 gr and work up but case capacity is already maxed out. I don't have a problem switching powders. I was just looking to use my current load as a starting point with the current powder.

I don't see 33 listed in the hornady 10 manual - and all the other powders max out in the 90-93 gn area for the 250s. Knocking Alliant's max data for 250s down by 10% puts you at about 90 gn. You may want to start there and see if you get the speed you want before you run out of case capacity.

Running out of capacity before you hit your desired speed is typical of a powder that's too slow burning for your application - but I'd try a basic speed/pressure ladder before I swapped powder and brass. Over to you.
 
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I dunno about H338LM brass but their 300WM brass varies from 230-242grs depending on lot. That’s a pretty big swing.

What does your H brass weigh?
 
Currently I'm loading 98 gr. behind a 285 gr. ELDM. Figured I'd be OK starting there with the lighter 250's and work up. Guess it's not in the cards. I'll just do another work up. Thanks for all the replies. This is still the best resource for practical information.
 
I dunno about H338LM brass but their 300WM brass varies from 230-242grs depending on lot. That’s a pretty big swing.

What does your H brass weigh?
Current batch is between 312 and 318 grains.
 
That’s pretty close to ADG, although ADG is hard and will handle pressure better.
 
Why would you want to go down in weight/BC? You'd need to drive them quite a bit faster to equal the 285's, using more powder and increasing wear on the throat. In this case, my suggestion would be going to 4831SC, but a better way to go would be 300gr Bergers or Scenars
 
CoryT,

Because I'm an idiot and can't leave well enough alone. I love to experiment. I have a healthy supply of my pet load for that rifle so I thought I'd embark on another quest.
 
Experimenting is great, however, one might seek improvement and have just as much fun. Try the 300's. Or try the Warner solids.
 
I looked at the Flat Lines. I think I'll take a deeper look there. Thanks for your input. BTW what are you loading?
 
For 338LM, I load all the Hornady 285's, primarily the ELD-M's at this point and the 300 Berger, as the AXMC likes them better than the 285's. I'm playing around with the Warner Tool 256gr, I need a faster twist for the 285's, but I've had great success with the .375's in the CheyTac. I use Retumbo in all there, though I have IMR 7977 and some H1000 worked up as well.
 
Nice. Thanks for sharing. Have you looked at the Lehigh Defense 257 ELR? Insane BC if it holds true