The Firing Line Forums - View Single Post

Powderman · October 28, 2001, 06:23 PM

If it's Winchester, perhaps I can help.

I own a .300 Win Mag Laredo, and have found the following out about the rifle and caliber.

First, the .300 Win Mag is capable of outstanding accuracy--but, usually not with factory loads! Why? Because, for some reason, most .300's are designed with very long throats. Long Range rifle accuracy is usually found to be best when the bullet is seated to within a short distance of the lands, or barely touching. The max recommended OAL for the .300 Win Mag is 3.340. That is usually the longest seating length to get the cartridges to still fit into the magazine.

My rifle likes IMR 4831, 70.0 grains, using the 175 grain MatchKing seated to an OAL of 3.510. I also use Standard Match primers. Federal seems to be the most consistent, although I have had good luck with CCI Benchrest also.

Also, I have found that my rifle likes factory new cases. It will shoot neck sized cases just fine, but for the best accuracy, I use factory new cases. Be prepared for a lot of experimentation.

October 28, 2001, 06:23 PM	#2
Powderman Senior Member Join Date: September 7, 2001 Location: Washington State Posts: 2,166	Is that Winchester or Weatherby Mag? If it's Winchester, perhaps I can help. I own a .300 Win Mag Laredo, and have found the following out about the rifle and caliber. First, the .300 Win Mag is capable of outstanding accuracy--but, usually not with factory loads! Why? Because, for some reason, most .300's are designed with very long throats. Long Range rifle accuracy is usually found to be best when the bullet is seated to within a short distance of the lands, or barely touching. The max recommended OAL for the .300 Win Mag is 3.340. That is usually the longest seating length to get the cartridges to still fit into the magazine. My rifle likes IMR 4831, 70.0 grains, using the 175 grain MatchKing seated to an OAL of 3.510. I also use Standard Match primers. Federal seems to be the most consistent, although I have had good luck with CCI Benchrest also. Also, I have found that my rifle likes factory new cases. It will shoot neck sized cases just fine, but for the best accuracy, I use factory new cases. Be prepared for a lot of experimentation. __________________ Hiding in plain sight...