338 LM Lapua brand brass question

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Longboat

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I'm reloading Lapua 338 LM brass and has 4 firings on it now. Shoulders get bumped .002" each reload.

Just wondering how many firings I can expect from Lapua 338 brass? Reason I ask is, after each firing the cases grow from trim length of 2.714 up to 2.723-2.726, right about the max case length of 2.724

Other cartridges I reload such as 308 and 6.5CM grow very little if at all. I can probobly get 3-5 firings before I have to trim them to length.

I'm just worried about losing so much brass each firing and risking a case head seperation eventually.

Is this normal for 338 Lapua brass to lengthen .008-.011" each firing?

Also, sort of same topic, I see brand new unfired brass in 308 and 6.5 actually get shorter sometimes after firing??? Most recent example is my buddies RPR 308. After firing new brass, some of the cases actually got shorter. Some even below trim length of 2.005". They ranged from 2.000-2.008" even though they started out at 2.005" or more brand new out of box.

What the frigg???
 
It's not the relation of the chambering it is the strength of the load.

Hotter load more brass stress, mild load, less stress.

As for your buddies, they likely expanding to fill the chamber, try just next sizing those ones now and I bet the get longer this go around.

I found my new brass to lengthen for little at the start.

A moderate load in a low pressure chambering will have quite long brass life with Lapua, I wouldn't even hesitate to say you could get 10+ firings.

I wouldn't bump any shoulders unless it isn't chambering.
 
Lapua brand .338LM is manufactured to be harder at the case head and get steadily softer toward the mouth. The case heads are actually very strong so it's possible they could separate elsewhere. I'd cut back on powder until you see minimal stretch if you want them to last.
 
I don't think my loads are that hot. I'm running about 2700-2750 with either Retumbo or H1000 pushing 285 grain ELDM.

I know everyone's gun is different. But I know guys are hot rodding 285's alot harder than I am.

Also, this brass is from factory loaded Lapua 250 grain Scenar I picked up for a good price. Even after the 1st factory loaded firing they were damn near or at max case length. I don't think I'm running that hot. But maybe I'm wrong.
 
You're right, that's not very hot a load. I'm running that speed in .338 Norma with Norma brass, 300's and the same powders with virtually no case stretch. Do you have another lot or brand of brass to try? What type of action is it that you're using?
 
I do have a pail of once fired 338 Lapua brass I got from some sort of special forces dudes at my range. DND rents it and they leave Lapua brass on the ground.

I just measured some of theirs and they are at trim length of aound 2.714 after 1 firing. So not much stretch out of their high end rifles.

I have 10 of their brass that I resized and fired. And indeed it has stretched to max length or slightly past.

I'm shooting an RPR in 338.

I do anneal every firing if that may have anything to do with it.
 
Here's a little bit better info sorry. .

Measured my fired brass before resize. It grew from 2.714 up to about 2.719-2.720, so grew .005.006".

After a .002" bump it goes to 2.724 and even up to 2.728 which is passed max length. So that .002 resize does stretch it out pretty good.

I would neck size only, but in the past on other calibers they usually get a little tight to chamber after 3 or 4 firings depending on brass and caliber etc. So just started bumping .002 like most do to avoid that BS. Plus you have the same case capacity every shot.
 
I’d go 10 firings by then the case heads will done neck sizing works for lighter loads but if you want it to chamber full size i like, could try for 0.005-0.001” of shoulder bump but have to measure or try them to check for ease of chambering.
 
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