Bullet design question for long freebore

[Bulseyetom]

I have a 40-70 SS rifle with a 0.408 bore and a freebore of 0.410 that is 0.300 long. I have a boolit that shoots great with smokeless but I have to have several grease grooves exposed for the bullet to just engage the rifling when chambered. I am thinking of having a new boolit mould built that eliminates the top groove (3 would be left) and make a section that is 0.250 long at 0.410 diameter. Using 20:1 alloy, would this work with a length of 0.250 without any lube? Looking for a hunting boolit that is easy to carry in your pocket! Thanks. Bulseyetom

[waksupi]

Don't worry about exposed grooves, it's time to think about powder coating.

[Wayne Smith]

Are you loading smokeless or the Holy Black? If Black you need to look at your lube adequacy - if you remove a groove you may need to deepen the ones left or add a lube cookie.

[gwpercle]

You don't have to put lube in the top lube grooves . A good lubricant sometimes is less accurate when all the grooves are filled .
Have you tried shooting the boolits when they are not touching the lands ... no law says they have to and accuracy might be just as good .
I would seat the boolit a little deeper into the case and not put lube in the top one or two grooves ...
Also use a quality lube like SPG .

Unless you are looking for an excuse to have a custom mould made , a quality lube and not filling the exposed lube grooves should do the trick . Poor lubes and Black powder might need as much as possible but Modern lubes are very efficient at keeping things lead-free ... Worth a Shot !
(Sorry about the bad shot pun ... I couldn't help myself )
Gary

[Bulseyetom]

I am shooting smokeless with the bullet. I use either Javalina lube or SPG and am not shooting very fast with 1600 fps or so maximum velocity. I will try a few lubed only on the bottom grooves and see what happens. It is easy to do as I pan lube everything. The extra long freebore length of 0.300 is a royal PITA sometimes! Thanks for all responses. Tom