Here's some of my experiments with my .300 OSSM:
Hornady 140gr Monoflex 44-47gr IMR 8208XBR 2914-3057fps Accuracy load 46gr @ 3034fps (1.2 MOA)
Speer 150gr HotCor 41-46gr IMR8208XBR 2562-2890fps Accuracy load 43gr @ 2700fps (.92 MOA)
Speer 150 HotCor 44-49gr Varget 2490-2960fps Accuracy load 49gr @ 2960fps (.52 MOA)
Nosler 150 BT 45-46gr IMR 8208XBR 2830-2880fps accuracy load 46gr @ 2880fps (1 MOA)
Speer 150gr DeepCurl 45-48gr AR-Comp 2808-3013fps Accuracy load 45gr @ 2854fps (.6 MOA)
Speer 165gr HotCor 48-50gr Varget 2818-2920fps Accuracy load 49.5 @ 2904fps (.82 MOA)
Speer 165gr HotCor 45-48gr AR-Comp 2750-2963fps Accuracy load 47 @ 2862fps (1.4 MOA)
Hornady 168gr Amax 46-48gr RL15 2700-2820fps Accuracy load 47.5gr @ 2800fps (1.2 MOA)
Hornady 168gr Amax 46-48gr Varget 2700-2778fps Accuracy load 47.5gr @ 2760fps (.98 MOA)
Hornady 180gr SP 43-46.5gr AR-Comp 2679-2854fps Accuracy load 46.5 @ 2854fps (.75 MOA)
Nosler 180gr PP 43-45gr AR-Comp 2660-2770fps Accuracy load 45gr @ 2770fps (.63 MOA)
These were wide ranging load load jumps without zeroing in on a tighter range of load weights around accuracy nodes, so the ultimate accuracy is indeterminate, but it gives you examples of the power in the upper. They are the culmination of 3+ month's work going out about once a week. I will be going out tomorrow to try the Hornady 180gr bullets with both 8208XBR and Varget, along with some more Remmy Accutips with different taper crimps applied over the factory crimp.
It is not expensive to shoot if you reload. Basically, you buy a bag of Winchester 25 WSSM brass, anneal them, either resize using an neck expander or fireform them to 30 caliber (I've done both) and you're all set. I've gotten my best results with fireformed brass using Mike Milli's (dtech.com) process.
I've about run the gamut with it and am looking to try a new caliber now. Times being what they are finance wise, I'll probably sell the .300 OSSM upper, reloading equipment and some preloaded rounds to someone to finance my next foray. It has been fun developing around that caliber. I'm either going to go in the direction of an AR10 based system, or wait and see what shakes out with a 450b necked down to 6.5mm at some point in the future. The .358 WSSM has some appeal as well as the .44 Claymore being developed over on beyond556.com.
Gotta keep expanding my horizons.
Hoot