The Firing Line Forums - View Single Post - My first bolt gun, 300 win mag, What mods to do?

Powderman · March 7, 2013, 11:02 PM

If you haven't sent the rifle in yet, choose your long range bullet first. Load two or three dummy rounds (no primer, either) to the OAL that will fit in your magazine. Send them with the rifle, and specify that you want the loaded round to place the bullet's bearing surface (ogive) .002 off the lands.

If you HAVE sent the rifle in, try to call them and do the same thing. If you're using the rifle for long range, you'd be hard pressed to beat a 175 grain MatchKing as your bullet of choice.

Here's why:

I have a Winchester Laredo in .300 Win Mag. The SAAMI spec for the cartridge calls for an OAL of 3.386 inches. When I shot loads that actually fit into the magazine, I was lucky to get 3" at 100 yards.

Through experimentation, I finally found a good load:
(NOTE: This load is safe in my rifle. Work yours up slowly, and reduce the starting charge by 15%--watch for signs of overpressure.)

175 MatchKing on 71.0 of IMR 4831, Federal STANDARD primers, loaded to an OAL of 3.510. This put the bullet .002 off the lands. You see, many manufacturers give the .300 Win Mag a super long throat. No, it won't fit into the magazine...but it will shoot 0.5 MOA all day long, and frequently better than that.

March 7, 2013, 11:02 PM	#20
Powderman Senior Member Join Date: September 7, 2001 Location: Washington State Posts: 2,166	If you haven't sent the rifle in yet, choose your long range bullet first. Load two or three dummy rounds (no primer, either) to the OAL that will fit in your magazine. Send them with the rifle, and specify that you want the loaded round to place the bullet's bearing surface (ogive) .002 off the lands. If you HAVE sent the rifle in, try to call them and do the same thing. If you're using the rifle for long range, you'd be hard pressed to beat a 175 grain MatchKing as your bullet of choice. Here's why: I have a Winchester Laredo in .300 Win Mag. The SAAMI spec for the cartridge calls for an OAL of 3.386 inches. When I shot loads that actually fit into the magazine, I was lucky to get 3" at 100 yards. Through experimentation, I finally found a good load: (NOTE: This load is safe in my rifle. Work yours up slowly, and reduce the starting charge by 15%--watch for signs of overpressure.) 175 MatchKing on 71.0 of IMR 4831, Federal STANDARD primers, loaded to an OAL of 3.510. This put the bullet .002 off the lands. You see, many manufacturers give the .300 Win Mag a super long throat. No, it won't fit into the magazine...but it will shoot 0.5 MOA all day long, and frequently better than that. __________________ Hiding in plain sight...