I'm having some work done on a custom m98 in 7x57 and the chamber needs to be re-cut. The gunsmith asked what chamber length I wanted, he is thinking possibly a longer throat for using the full case capacity.

My plan is to shoot 140 and 150 grain bullets.

So what says the hive?

Thanks gents for the info!


Perry

You decide on that; but first define "longer throat". How long is long? I don't try to hot rod the 7x57; most of the time guys want the short throat reamer I have specially ground for the 139 grainers, in 275 Rigby. Some want the 175 grain throat too.
140 and 150 lead core grainers do not go below the neck anyway.
Just make sure that whatever throat you get, your magazine will handle the loads without too much bullet jump, which may or may not be a problem.

What is the twist rate of the rifling? That will determine your best choice in bullet weights. However, even light bullets like the 139 grain will shoot well in a 1:8.5 rifling if slowed down.

Rifle has a twist of 1:9.
In my mind I am thinking the COL ought to be in the 3.00" - 3.100".
That should suffice 140's to 160's.

Perry