Good afternoon

I have a friend that tried these in a 243 Win with a Walther 1:8 barrel and they break up when they leave the barrel. Is this common for this bullet? It does not happen with any of the other bullets tried.

Any ideas of what might cause this?

Pieter

m77, my best guess would be rate of twist and/or speed or a combination of the two.

Your question reminds me of a story I read of a person that took the 8mm magnum case and necked it down to a .17 caliber. The .17 eargensplittenloudenboomer is what he called it.
His problems came from bullet construction and the rate of twist and speed of the loads he developed. He couldn't get any to hit a target at 50 yards and barely could get them through the screens to read speed. In that case, all three aspects; bullet construction, twist rate and speed of the load combined to tear the bullets apart.

Bad batch would be my guess.