300 WSM brass to 7mm WSM

[ZSteinle]

Can 300 WSM brass be fire formed to 7 WSM? I know the difference in the two is very minimal. Has anyone tried it?

 

[geargrinder]

Yes, I've done it. It's the best way to take advantage of the great Norma brass.

300wsm brass is a great starting point since all you need to do is neck down making a false shoulder that will headspace nice and snug.

Load them up and shoot.

Here's a picture of a false shoulder next to the parent case.

 

[ZSteinle]

how do you fire form them? Do you actually load a bullet in there or do you just use like 8 gr. of a pistol powder with a bit of a napkin in the case to hold the powder in the case and to start to form some pressure?

 

[ourway77]

I have loaded a reduced load in the powder I wish to use and fired away perfect forming. .308 to .284 you may have to turn the necks, but shoot them first and drop a bullet in the spent case if it falls through easily your good to go but if not they will have to be turned. If anyone knows a better way (Maybe Micrometer) correct me. From the looks of the picture you may have to force the bolt shut hard but afterwards they will chamber very easy. Lou

 

[geargrinder]

I use a moderate load and mid weight bullets.

I have a sub MOA fire forming load so I take them hunting as well.