Can use my.40 for my 10mm?

[oLa]

Yup... same bullets are fine. Only thing that I would not do is load plated bullets into 10mm due to its power but either lead or jacketed are fine.

[Hoser]

.400 diameter bullets work in any .400 cartridge.

. Only thing that I would not do is load plated bullets into 10mm due to its power

Where on earth did you hear that? Plated bullets pretty much suck at most all pressures when you are looking for accuracy.

The last thing I would use in a 10 is lead.

[oLa]

Lead should shoot fine in 10mm (though I wouldn't shoot it in a glock or other polygonal barrel due to the fouling).

Jacketed is obvously best.

Plated sucks at anything stronger than plinking loads. High pressure/velocity and the plating can come off.

[Hoser]

Lead should shoot fine in 10mm (though I wouldn't shoot it in a glock or other polygonal barrel due to the fouling).

Jacketed is obvously best.

Plated sucks at anything stronger than plinking loads. High pressure/velocity and the plating can come off.

"Should..." Lead bullets can be anywhere from soft with crappy lube to hard with good lube. When you start running a 10mm up there, soft lead will really foul a barrel. Even worse if they use crappy lube and you use a hot powder.

If you are shedding plating, you are using too much crimp.