New brass vs Used brass?

[williaada]

Just started reloading, and I noticed when I used my chrono the new brass was between 75-100fps slower then the once fired brass. Has anyone experienced this before?

 

[Blaser270]

Neck tension on the new brass may be greater. And “used” brass, no telling how many times its been fired or sized, neck wall thickness, etc. lots of variables.

 

[MThuntr]

buy new brass (100 from same lot)
fireform via about any method. I've done starting loads with cheap bullets (pre covid hoarding) however cream of wheat method works also.
then do load development

Believe it or not I'm going to add a Lee Factory Crimp die to test. The guys at Hammer Bullets Forum really preach improved consistency due to neck tension which likely would be resolved with a bushing sizing setup but I'm cheap and don't want to rebuy dies.

 

[Blaser270]

Received a box of new brass yesterday. Free shipping at Midway is very inviting. Headed to the range with them using the cheap stuff at short range on life size paper deer targets (now they’re fire formed). Load work-up all year off of a bench really messes with me come hunting season if i dont switch it up.

 

[cahunter805]

Just started reloading, and I noticed when I used my chrono the new brass was between 75-100fps slower then the once fired brass. Has anyone experienced this before?

New brass is almost always undersized and when fired will expand and form to your chamber. This results in a bit of extra case capacity and the reason you should always work up loads with once fired brass.
Also it’s a good idea to run all new brass through your sizing die to straighten necks at least.

 

[Brian in Montana]

I have noticed that effect as well, but it never occurred to me that it was the neck tension. I figured it had something more to do with the fit of the casing in the chamber effecting the efficiency.

I'll use never-fired brass in load development sometimes, but I always use fire-formed brass for a finished product. Ammo for hunting.

 

[N2TRKYS]

I haven’t noticed any difference in mine. I don’t waste my time and energy on fireforming. I work up loads with virgin brass and find it very easy to duplicate those loads in the next loadings.

 

[ImBillT]

I’ve never seen a difference, but I full length size before I fire for the first time.

Any possible variables other than being once fired vs new?