load workup - new brass vs FL sized

[ChemE1975]

I was reading another thread and it mentioned case capacity of new brass vs once fired, etc. I did not want to hijack that thread, so here we go.

the new rifle is on the way and now i am thinking of working up a load. i plan to use new lapua brass, varget or IMR4064, berger full bore 155.5 and russian primers. these are the components i have. rifle is AE Mkiii with a 20" 1:12 barrel.

Question- if i work up a load using new brass, will i need to work it up again once i have shot all of the new brass and thus i am using once fired and FL sized cases?

does case capacity change enough to warrant a new load work up?

 

[rduckwor]

While I generally do not advocate sizing new brass, it isn't a cardinal sin to do so. Normally I just clean up the necks and make sure the dings are removed and at most neck size new brass.

Why not take a component quantity of your new brass, and set your F/L sizing die up? Then load 10-20 of each: new brass that hasn't been sized and new brass that you have F/L sized and run both OCW runs.

That will tell you how well your sizer is taking your brass back to square one. It's hard to have too much knowledge and collecting data is tantamount to knowledge.

It won't be a huge amount of work and will be a great step on the road to breaking in a new gun and a good days worth of work gathering data and shooting.


Good Luck,

 

[ChemE1975]

That is a cool idea to initially check on new brass vs FL sized brass. Like you said, good data gathering.

 

[ChemE1975]

Maybe I should rephrase my question to ask what is customary and what do others do?

 

[Sethshaun]

While I generally do not advocate sizing new brass, it isn't a cardinal sin to do so. Normally I just clean up the necks and make sure the dings are removed and at most neck size new brass.

Why not take a component quantity of your new brass, and set your F/L sizing die up? Then load 10-20 of each: new brass that hasn't been sized and new brass that you have F/L sized and run both OCW runs.

That will tell you how well your sizer is taking your brass back to square one. It's hard to have too much knowledge and collecting data is tantamount to knowledge.

It won't be a huge amount of work and will be a great step on the road to breaking in a new gun and a good days worth of work gathering data and shooting.


Good Luck,

Good advice. I neck size only-to make sure I get consistent seating depth New brass sometimes has random looser necks and that tends to let the bullet seat deeper with the same setting.

With a new rifle, after the brass is fired once I like to take measurements on the neck, shoulder, case head, overall length and headspace. I use that to see what my dies are doing vs the chamber dimensions. I use the results from shooting fresh brass as ball park and after I set my dies I fine tune. There shouldn't be a huge difference between new lapua and full length sized lapua except for neck tension will be probly be tighter. If you find a good load with new brass your groups might tighten with the same load after you get your dies/seating depth perfect.
Write down everything for reference later. I forget almost everything from the last time I loaded. Notes help not waste time by not having to retrain your brain every time.
The only way to really know is to do your own experiments with your own equipment.
Have fun

 

[roggom]

Generally new brass is -.004 so it should fit in any rifle. You can work some loads to get you in the ballpark, but you really wont know your own rifles headspace until you fireform said brass in that rifle. FL sizing does not go down the entire length of the brass. Once you fire the brass in your rifle it changes the brass, it expands to fit the chamber. You can side down the body and bump the shoulder but never get it back to virgin state.

In short, you can work up an OCW with virgin, pick a node, find your bump and then validate with once fired. You will then know your rifles HS, the node, then you can work on seating depth.


The worst case scenario is if you oversize your brass and have too much HS, then end up with fail to fire. That would suck.

 

[NCKan]

I just resize the neck to remove any dings them chamfer and deburr. I use a neck die if I have one, or back a FL die backed out so that the neck at least goes over the expander button. I know a guy that dosen't do a single thing to new brass other than load it....and it shoots nasty little groups. He may not be the norm. As with most things, the quality going out is usually equal to the effort going in.