Switching brass questions...

[DoubleGobble00]

So I've developed a decent load for my 300 Rum with Nosler brass but my brass developed donuts and primer pockets are getting loose. So I ordered some ADG brass for it.

I know the ADG brass will probably be thicker and less H20 capacity, so it'll probably use less powder to get same pressure/velocity.

Here's my question, should I start load development all the way over or just load a grain under my existing load? Should I try to match velocity of my existing load? What do you do when changing brass?

I'm thinking I should load 3 rounds at 0.5 less than existing load, then existing load, then 3 rounds 0.5 grains over existing load.

My existing load is 2.5 grains less than max pressure when using Nosler brass.

Thoughts?

DoubleG

 

[sedancowboy]

Weighing each brand of brass will give you some idea. I would start lower with a case of that volume and work up with a ladder to see where pressure is. Then I would load at the velocity you are at now. On ADG website they recommend starting at least 2 grains below your current load due to volume of their brass.

 

[sourdough44]

Yes, as you may of posted, another factor can be how much below max you already are, averages. I realize many post how they 'developed' their own max. That's all fine when done carefully. I'm more the type to stick within book data ranges, yes they vary, than going above.

I've been reloading for many years, nary an issue yet, seem to kill stuff just fine.

 

[DoubleGobble00]

Thanks... yeah a new ladder would be helpful and get me the velocity data I need also.

I determined my existing load max by ladder also and stopped at ejector mark and bolt slightly sticky. I'm 2 grain under that now.

Through experience, if you match velocity of previous load with new brass, did it shoot good? Or did changing brass change the optimum velocity?

 

[sedancowboy]

Usually if I find the same velocity using the same powder and primer I find good accuracy.

 

[ar10ar15man]

i would shoot a ladder looking for the velocity of the previous load
AND see how it looks in the ladder.
ya need some software to calculate what happens when vol a brass is replaced with vol b brass.

 

[Okanogan]

I have some ADG brass for my 300WM where I normally use Norma brass. I have not done a load work up yet for the ADG brass but had planned on trying to hold COAL while looking for similar velocity. The WM seems a little finicky on SD/ES so I plan to try a little up and down from the velocity match to see if it changes SD/ES measurably.

 

[entoptics]

Weigh enough pieces of each brass type to get a decent "average weight". I recently had this exact scenario, going from MAI (Norma) to Sig Sauer. There was nearly 40 grains difference between the two brands.

After testing, it appears that the Sig Sauer (~255 gr) requires ~1.5 - 2 grains less powder to get the same velocity as the Norma (~215 gr).

Also note, that after firing the new brass once, the interior volume will likely change substantially, so you may need to do another test to confirm your load/velocity does or doesn't need a tweak.

 

[taly01]

but my brass developed donuts and primer pockets are getting loose

I would load a few of the new (heavier?) brass, say -5 -4 -3 -2 -1 % and shoot over a chrono to find out where you are. Starting hot and overloading a 300RUM would be a nasty explosion!

If only changing brass if you match your previous velocity using a chrono you should have the same accuracy node.

 

[Doug Herold]

I was in the same predicament with the Gap4s recently ( with the nightmare brass availability situation ). I dropped 10% of the grain weight, did a ladder, and worked up from there to find a node.

 

[fabricator21]

I use quickload. Adjust the h2o volume for the new case the lower the powder charge until you get back to the desired velocity. you may have to tweak the actual load a 1/10 of a grain either way.Verify with test groups.

 

[DoubleGobble00]

Thanks! I got the brass in this week.. I'll work up.