Help/advice on 300 Win Mag headspace

[CatShooter]

pbike257. He's a member here. He doesn't have a website. Makes great tools, though.

https://www.youtube.com/watch?v=-QW-5npXJKs

Thank you Toby... I sent him a message!

 

[cbacejr]

I would like to thank everyone for all their help!

 

[Will Henry]

Headspace on belted case is measured on the belt. Minimum chamber is .220. Now, most brass is closer to .214 to .216. I have never seen over .218. On the 300 Win Mag, Winchester was especially cavalier when it came to producing brass with a consistent shoulder dimension.
Reloading is simplicity exemplified. You turn your sizing die down enough to lack about 3/4 turn to bump the shoulder. Try the case in your rifle. It will likely be difficult to close the bolt. Turn the die in until the case just chambers with a slight feel and Bob's your uncle.
The difficulties with the 300 Win Mag (like the 7mm Rem) arise from its short neck, minimal body taper, and wide tolerances in the head to shoulder dimension. This applies to the brass, the dies, and the rifles.
One friend of mine used to bore the belt recess on the dies to allow the die to size to the shoulder on new brass. He then chambered the rifle to this depth and cut the belt recess to .218 with a boring bar. This worked out OK for a match rifle, providing the owner was capable of dealing with the idiosyncrasies of this type of set-up. Depending on the length of the brass, it could be necessary to trim to length at the start. For a hunting rifle, I think it is foolish to build a rifle which is unlikely to be able to use factory ammunition, unless you want to hunt with a wildcat. WH