I think you will find that the #11 Mag caps will fit just fine and snugly on the White breech plug and nipple. You do not have the option of just replacing the nipple.

On all of my Whites if you install the cap with a capper and push it on with some force - the only way you will get it off is using a knife blade to peel it off.

Also a really good cap to use is the RWS #1075+ cap - hotter than a regular Musket cap and really tight in the nipple. It is 10.75 instead of 11.

And I totally agree with those that are saying stay with the percussion cap - with a white there is no real advantage to the 209. I had several conversation with Doc about this as I immediately switched to a 209 hammer and breech plug... In the end he won out I have switched all of them back to a #11.

When you put it on the nipple correctly it becomes virtually water proof.

Shoot or no Shoot??? If you plan to hang on to it for value and then re-sale it - don't shoot it! If you are a shooter/hunter use it - it really is a good rifle.

The one negative is the recoil lug - if it has the blade recoil lug heavy lead shooting can actually bend the blade. If it has the square block recoil lug - shoot howitzer shells out of all day no problem.

Above all - what ever you do - take of it there are not to many in the condition you describe left to find.

It,s a shame the Co.went down the tubes especially before the inline craze.

I have used the #11 system on all my White rifles and never lost a cap yet. I have the safety on, and from time to time just visually check the cap. Like I do on all my percussion rifles.