300 Win mag loading help

[rodeojoe]

Have a 300 Win mag in a Winchester 70 w/26" sporter barrel.
Picked up a box of Hornady A-max in 178grain lead.
Have CCI mag primers.
Have MRI 7828 powder.
Have new Remington brass.

All I need is the amount of grains of powder for max long range accuracy. Don't have much time to mess around with it, so I figured maybe someone on here has already came up with there perfect loads.
Thinking about 75 grains of the 7828 powder.
This is not a picky rifle and groups over the counter loads well.
Any thoughts on this?

Using an 8x32x50 30mm scope on top.

 

[DaveB]

That load IMR7828, not the ssc, will work fine as a starting point. I believe that load will be compressed.

I have a M70 in 300 WinMag with the sporter barrel and found it to be hopelessly inaccurate with 180 grain bullets but MOA with 150's. I will also say I constantly pushed max load numbers with many types of powder and never really backed off to see if I could tighten up the groups. I use IMR7828 77.5 grains in my Browning 300 WM with BOSS and I have it tuned so it shoots 1/2 inch groups all day. If you can stand the noise, blast, and dirty looks from everyone at the range. I gotta get the replacement BOSS that does not have the recoil reducer as part of the package.


If you start getting unrepeatable groups let me know. I use Fed215M primers and Nosler Ballistic and Partitions.

 

[rodeojoe]

I figured 75 grains would be close to 100%case capacity.
Are you using 77.5 grains of the 7828 with 150 or 180 lead?
308 lead is hard to come by right now, the 178 hornadys was the best I had to pick from localy. And they were hard to come by.
This M70 seems to do fairly well with cheap over the counter 180 ammo. But I like to handload when I can.

That load IMR7828, not the ssc, will work fine as a starting point. I believe that load will be compressed.

I have a M70 in 300 WinMag with the sporter barrel and found it to be hopelessly inaccurate with 180 grain bullets but MOA with 150's. I will also say I constantly pushed max load numbers with many types of powder and never really backed off to see if I could tighten up the groups. I use IMR7828 77.5 grains in my Browning 300 WM with BOSS and I have it tuned so it shoots 1/2 inch groups all day. If you can stand the noise, blast, and dirty looks from everyone at the range. I gotta get the replacement BOSS that does not have the recoil reducer as part of the package.


If you start getting unrepeatable groups let me know. I use Fed215M primers and Nosler Ballistic and Partitions.

 

[mr.big]

I always had better luck in the Win mag with faster powders,,I would start with IMR 4350 and IMR 4831

 

[DaveB]

That is my Browning load and that rifle is 180 Partitions only. The rounds are loaded out so far I have one in the chamber and one in the magazine, and that's it.

I have tried IMR4350 and it is accurate but the IMR7828 is what works in the Browning. I use IMR4350 in my M70 with 150 grain Partitions.

.308 lead is indeed difficult to come by, every bit as tough as .224. I stocked up starting last spring, picking up rounds at Shooters Pro Shop, a place I recommend all the time and visit at least twice a day. Bullets come and go so fast you have to be persistent but the prices are very attractive.