higher velocity accurate 300 win mag load

[briang7511]

I am looking for some assistance with a 300 win mag load. So far my rifle (rem 700 sendaro) only prefers lower velocity loads. Accuracy falls off after 2600 - 2700 fps with heavier bullets and 2700 -2800 fps with lighter bullets. I have tried IMR 4064, IMR4350, Reloader 22, and H1000. Best results were with 74gr H1000 and 208amax .030 off the lands. Also tried some .010 off the lands with same results. 3 shot Groups around .900. I have also tried Fed gmm ammo which is around 2900fps with 190gr sierra hpbt and got groups around 2 to 2.5in. HSM ammo which is similar to the GMM groups around 1.5 to 2.

My goal with this rifle was to create an accurate higher velocity load than my 308 to reach 1000 yds, then beyond. I am up to approximately 500 rds through this gun and still searching. When i reach max loads the bolt does get sticky.

 

[Grumulkin]

This load works for me; I don't know if it will work for you. If I remember correctly, muzzle velocity is about 2,850 fps.

You may have to resign yourself to the fact that your rifle will continue liking "lower velocity" loads and it may not be capable of groups better than 0.900 inches.

 

[MCMXI]

I have tried IMR 4064, IMR4350, Reloader 22, and H1000. Best results were with 74gr H1000 and 208amax .030 off the lands.

I've found Reloder 22 and the 208gr A-MAX to be very accurate in both of my .300 Win Mags. I worked up the load below for my Remington 700 with a Krieger barrel but it shoots very well in my AI too. Those are two 5-shot groups shot on the same day at 100 yards. I adjusted the scope after Target 1 on the right. The bullet is .020" off the lands in the Krieger chamber and the brass (W-W) was on it's third firing with neck sizing only. The A-MAX is a secant ogive style bullet and they tend to do better being close to the lands.

 

[briang7511]

Those krieger barrels are nice. I agree that i may have reached the rifles potential. I am going to stretch it out to 1000yds with what i have but rebarreling is in my not so distant future. Thanks for the input.

 

[GooseGestapo]

Try Retumbo and Reloader25. These may get your targeted velocity before maxing out on pressure.
Try some Norma brass. They typically will hold slightly more powder than the W-W brass.

Also, you may need to try having the chamber throat lengthened. This may allow higher velocities before pressures start messing with things. Lastly, you may need to try another barrel.
Also, this may be a situation where cryo-treating the barrel might make a further difference.