Retiring/Changing brass

J

jpbaker

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Im getting ready to change my brand of brass in my .308. I am switching from nosler to lapua.

Nosler weighs 164.4gr and the Lapua weighs 172.5gr. I was a little surprised at the difference between the two. Considering the difference, should i restart load development. My pet hunting load is 168ttsx over 46gr of varget.

Tks
Jordan
 
46 grains of Varget is over max by a half to a full grain for a 168 according to both Hodgdon(full grain) and Barnes(half). Hodgdon just happens to list a TTSX too. So yep, you need to start over.
Not a horribly unsafe load though. One grain, even compressed, is highly unlikely to give you any grief. Likely won't fit in the over priced Lapua brass though.
 
jpbaker said:
Im getting ready to change my brand of brass in my .308. I am switching from nosler to lapua.

Nosler weighs 164.4gr and the Lapua weighs 172.5gr. I was a little surprised at the difference between the two. Considering the difference, should i restart load development. My pet hunting load is 168ttsx over 46gr of varget.

Tks
Jordan
Click to expand...

With the variation in case weight, you'll likely find a variation in internal case volume, which will affect the internal ballistics. Some internal volumes from weighed cases a few years back was showing me 56.0/56.6/57.7 gr of water in Lapua/Norma/Winchester respectively. You'll need to develop a new load the usual way ... start low, work your way up ...
 
Also, keep an eye on neck clearance. lapua has very thick necks. Some chambers are not designed for brass that heavy.

If you are experiencing high pressures with start loads, consider check the fired brass for adequate expansion. Try and drop a bullet into the fired case neck.

It should fall in without any resistance in a typical hunting rifle. If there is resistance or the bullet needs to be pushed in, you will need to outside neck turn to create adequate clearance.

Something I check with any new rifle.... you just never know what reamer a factory may use.

Odds are you will be 1 to 1.5gr less then where you are now but use starting loads and work up.

Also, when using Lapua, you may need to change your sizing die to account for the really heavy neck. If you find that the resistance in your die is beyond what you prefer, outside neck turn will help.

For my competition shooting, I have found 11 to 12 thou necks to be ideal for my PRVI brass which share similar traits.

Jerry
 
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