bullets tumble

[lite2bolt]

Noticed my bullets are tumbling, they are key holing. This just started a few weeks ago. the musket has well cleaned bore. No damage to the crown to the naked eye. Same bullet used for years and had performed very well. The only change was switch from GOEX to Swiss. went from 37 grains FFg to 30 grains Swiss FFg. I had expected wide groups but not the key hole. any suggestions?

[Maillemaker]

I'd say increase your charge of Swiss.

They say you can use ~10% less Swiss for equivalent charge of other powders. 10% of 37 grains would be 3.7 grains, so I would start with 33 grains of Swiss. It's likely you will need to do a complete ladder workup to find your optimal charge with the new powder.

[John Bly]

More powder

[WBowen70]

Mine was doing the same. went from .575 to .576, problem went away.

[Jim_Burgess_2078V]

Problem could also be a slightly harder lot of lead but the other advice received is worthy of consideration. You probably need at least 35 grains of powder and you also might need a slightly larger diameter bullet sizer.

Jim Burgess, 15th CVI

[Don Dixon]

Swiss is more forceful than GOEX, but your load is way too light to properly expand the ball.

[Fred Jr]

All the recommendation already made could be your problem. Hard lead, rounds too small, charge too light. The easiest thing to try first would be powder charge.

Good luck!!!!!

Fred

[clowdis]

All the recommendation already made could be your problem. Hard lead, rounds too small, charge too light. The easiest thing to try first would be powder charge.

Good luck!!!!!

Fred

Or just see if you can scratch your bullets with your fingernail. The lead should be soft enough to scratch.