Wow, I am shocked you got 3200fps with TBBC. Usually they build pressure so fast that 3100 or less is where you will be at. Besides a guy on here "GAHunter", I don't know anyone that has great luck with grand slams. My groups with Grand slams are usually 1.75" groups with 93gr of H1000 at 100 yards. Not good enough for me. I suggest you find another bullet. These two have low success rate if you are looking for .5" groups but terminal performance of the TBBC, is undisputed.

If you wanting a bullet that has a good reputation for accuracy, better stick with Sierras around 200gr. They might not hold together the best at close ranges, but hey, its 200gr's coming at them. You got alot of premium options, these days. Accubonds, Interbonds, partitions, Barnes. All these bullets I have seen shoots decent. I got best results from 180gr swift A-Frames. But shoot to use Barnes due to cheaper, I believe perform just as good as A-Frames for less of a price.

They are finicky, but if you have the pleasure to find a load that works, barnes is the bullet that RUM's all should be shooting. I found a 180gr Triple X load that works great at around 3190fps with 88gr of RL25. Seating makes a huge difference with barnes. I tried 3.580", 3.600", and 3.625", 3.650" COL, and 3.625" got clover leafes.

As far as the expert. All the ranges have these experts. You can decide for yourself if you research his "statement". Then you can judge everything else he says after that based off that decision. By the way, I have shot out a 300RUM. You can see accuracy drop after 1500 rounds but very slowly. Some sooner, some much later. I had it rebarreled, but it was still a 1.5MOA gun before rebarreling.