Winchester to Lapua load data?

[DropinLead]

I can find volume difference between various brass makers, link below for example from thehighroad.org. That does not translate to grains super easy. When looking a load data from Hodgdon for example in the link also below, it is stating Winchester Brass. It has a larger voume thant Lapua so pressures are different. I am trying to get a sense of the MAx load scaling. I tis less but i am unclear waht less is. Is it 1.5 grains or 5 graisn for example. If there is a resource that lsits that brass load difference I don;t have it, I would liek it. Let lme know the reference name and I willl get it. Since I don't have it, I figured those out here would have direct experience. What the scaling of min and most importantly max for Winchester Brassto Lapua Brass when one has published data for Winchester Brass? I am understanding a 5-6%% reduction for example going from 46 to 43 grains for example going from Winchester to Lapua. Looking to confirm that information out here as well. Thanks.


NOTE: The WCC shown is a NATO case and NOT Commercial. The BHM is a Black Hills Commercial
Various Brass capacity link -> http://www.fototime.com/08C65807F239B26/medium800.jpg
Hodgdon load data specifying Winchester Brass - http://www.beyond556.com/images/hodgdon/PDF/308Winchester.pdf

 

[varmint slayer]

I can tell you Lapua to Winchester in .243 is about 1 grain different with Lapua brass taking a grain less to do the same fps as 1 grain more in Winchester brass. 45.5 of H1000 in Lapua vs 46.5 in Winchester.

 

[Graham]

Lapua brass has less case capacity. Drop your powder charge accordingly.


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[DropinLead]

Varminst slayer thanks for that, I think I am jsut going to use 3% less rule for max and not exceed that as a max load.

 

[Graham]

Don't just take someone's word for it on the Internet. Measure it.


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[varmint slayer]

Yeah I agree with Graham on this one. Just start low and work your way up as normal when developing a load and just expect to hit max sooner than the book max.

 

[DropinLead]

Of course yes. The question was if Winchester = "X" for the max load then Lapua = "X-Y". I am looking for the answer to "X-Y". I need that to "measure" as you state. 3%-5% less than stated Winchester Max as the upper limit is in-line with what Varmint slayer said which was 3%.

Of course I have to measure to get that. As long as it is not like 20% less or something I know I am in safe boundary. The upper limit was what I was looking for, we all know it will max sooner than the book says. How soon in terms of an integer was the crux of the question. A Quantitative answer not a qualitative one.


Thanks much

 

[CEL317]

Different powders will have a different variations. For my rifle, I get the same velocity with Lapua brass at .4 grains less of IMR 4064 than Winchester brass. But like has already been said, just start low and work up.

 

[Dan Newberry]

It will depend on what cartridge you're working with, and what powder burn rate you're using.

When I go from Winchester to Lapua brass in the .308 with powders in the Varget/4064/W748/RL15 burn range, I find that Lapua brass needs .4 fewer grains of powder to hit the same accuracy node as with Winchester. With IMR 4895, it's more like .3 grains.

Work up from well below, of course... but do expect that's where you'll see the node.

I coincidentally just returned from testing some Lapua cased loads with the projected Varget charge weight reduction of .4 grains. My OCW with 178 AMAX's in Winchester (.308) brass has been 43.0 grains. Suspecting that Lapua brass should need 42.6 grains to match that pressure (in order to hit the same node as I was hitting with the Winchester load), I loaded some up at that charge (this is well far enough below max that I wasn't worried about backing down any farther.

Working through the plates from a 100 yard zero all the way to 1040 yards, and switching from the Lapua virgin cased loads to the Winchester, they stayed right with one another. So the conclusion was that 42.6 grains of Varget was my OCW with Lapua brass and 178 AMAX's.

Dan

 

[rduckwor]

The case capacity data you linked is mine, posted somewhere (I forget exactly where). Sadly, I didn't have a commercial Winchester case group to measure.

However, the others have given you good advice. Things seem to rarely work in a linear fashion with loading and precision rifle. Best bet is to work up any load you want to shoot using the components you intend to utilize.

The "X-Y" rule might be a useful rule of thumb, but don't expect exact results from it.

Good Luck,

 

[BuzzBoss915]

We can't rely on charts or Internet advice, unfortunately, there are no shortcuts. Handloading requires that you do your own work up.

I was just looking at my 243Ackley loads, with the Sharpie data noted on the lids. Same WW case but ever so slightly different powder. For instance IMR 4831 is 44.3 grains. Same bullet driven by H4831 = 47.7 grains.

I didn't get that from a chart, I did it by testing the load, commonly referred to as "working up a load". I never looked at Hodgdon's data, or anywhere else to tell me what my rifle likes. You have to do the homework, find out what the experts say and deduct 10% as a starting point. These practices have never been changed or modified. And, you have to take into consideration the exact load tested with the exact same components in the same type of firearm, or if it might be in a Universal Receiver.

I have (occasionally) seen some comments on this site where a shooter has a problem and says he looked at a certain source and used that max load data as a starting point. I don't know when, or how practices and procedures have reverted from self testing to relying on published data? BB

 

[DropinLead]

Thanks all.

 

[Skigolfmike]

For me, it's .5 gr less in the Lapua brass. 44.0 in Win brass, 43.5 in Lapua.

Dan, you need to shoot at sea level more. You'd learn to push your loads harder.

 

[DropinLead]

I am hearing .5 to 1.5 grain less. Jives with my 3% less guestimate. Interisted in hearing what you all saw through your own load development as a difference. It sets a frame of reference for me. Nothing more, nothing less. Just information.

Thanks!