Why Do Nickle Plated Cases Split Far More Often Than Standard Brass ???

[Zappa]

I just tumbled a mixed batch of nickled and brass .45LC's, about 1 in 10 of the nickled cases were split, but zero of the brass cases.
The same thing happens frequently with .357's, the nickle cases split often while it's rare with the brass cases.
Anyone have an explanation as to why this happens ????

 

[MACGYVR]

The brass is thinner to leave room for the nickel plating to make up the final ovaerall diameter.

 

[MAshooter1]

From a machinist's standpoint, nickel tends to be (I believe) much harder than brass and work hardens like a SOB when you try to cut it. Forming it back down (when doing resizing) will tend to work it, causing it to work harden and potentially crack if too much force is put into it. I could be completely off base here, but the link below is kind of pointing to the same issue (splitting).

Can You Anneal Nickel Brass? - LongRangeHunting Online Magazine

 

[MAshooter1]

The brass is thinner to leave room for the nickel plating to make up the final ovaerall diameter.

My best guess is that nickel plating is several microns thick, which if we go an extreme (4 microns is pretty thick) that equates to about a tenth and a half. That shouldn't cause the (nominally sized) case to misfeed I would suspect, so no need to undersize it.

 

[MACGYVR]

HEre is statement from Remington about .223 cases

•Nickel plated brass is not suitable for case forming as it tends to crack due to hardness greater than standard brass.

•Nickel plated brass is harder on reloading dies due to this greater hardness than brass.

•The nickel plating process deposits a layer of nickel on the brass. Many reloaders like its appearance. Nickel plating is very hard and very corrosion resistant, but it has tradeoffs. This nickel will crack if it's worked excessively during reloading. Too much neck flare or full length sizing may cause the nickel plating to flake off. This makes nickel plated brass unsuitable for fireforming wildcat or Ackley improved cases. Nickel plating has been known to be very abrasive on reloading dies.