Reloading for a 338-378

[bighorn1]

I have an older 338-378 the gun smith I got it from used 378 cases and put down loads in it to open the case out. Now I can buy unprimed any 338-378 cases and I have been reloading them. Will the gun using the new cases and same load still shoot the same my friend who reloaded said it would be different with the same loads. Just wondering.

[700xcr]

Each brand of cases has different case capacities. May want to start testing different powder charges.

[bighorn1]

Sounds like good advise. Thanks

[Oh Mah]

i have found that good brass shoots around a 100 fps faster than the cheap brass.the good brass holds less powder but creates more pressure because of it so you might want to cut about 2 grain off your normal load shoot see where your at.if pressures are good and your not to far off target you  are good to go back up to normal load.the diff. in brass has never been a lot so 2 grain will be plenty.

[Magnum_Willys]

Unfired Brass, neck-sized brass, and full-sized brass vary by 1/2 to 1 grain for me in performance.  You could weigh the two empty and full of water to compare powder capacities.  If similar capacity likely similarperformance.  But you probably want to shoot em in your rifle once then there should be little difference between that and your others when loaded similarly. 

I found my 338-378 brass needs annealing after just 3 reloads.  I anneal everytime now.

[Yondering]

I found my 338-378 brass needs annealing after just 3 reloads.  I anneal everytime now.

That's an indication of excessive sizing. If you use a case comparator in a digital/dial caliper, you can adjust the sizing die for minimum shoulder setback, which will prevent overworking the shoulder and body. Then pay attention to the sized neck diameter vs loaded neck diameter, and compare fired neck diameter as well.

[Magnum_Willys]

Depends - have all the tools but the die Im using the brass to fat to chamber unless .010 setback.  But have issues even with just neck sizing. If chamber matches die less of issue for sure. If not anneal is your friend.  But like stated overworking neck by shrinking then pulling expander thru causes issues.