Over all length

New to reloading. Reloading for a 257 bob short action and cartridge is to long for magazine
I don't mind shooting targets one at a time but for hunting would like to have a full magazine
Do I just shorten length until cartridge fits magazine? Help

Exactly. Shorten it up to about .005" less than mag length, and work up your load from there.

What's the best way to measure mag length?

By trying your loaded ammo in it. Just seat your bullets deeper a little at a time until your magazine will accept them without binding or any other goofiness.

Will do.. Thanks

I bought a Hornady over length gauge tool, it makes everything 10 times easier. Before it would take me a half hour or so, I would load a bullet long then jam it into the chamber a few times then take the average I was getting. Now with the Hornady I get an exact reading in 2 minutes and I'm done. I wish I spent the money for this thing a long time ago.