I have some HAHs in 360gr that are too long, so I was going to hit the noise and grind down, though their diameter is a smidge less than ideal.
When more of these guns get out to the public with customers using NSAs, Mr Hollowpoints and others, I think we will have a better map on best ammo. A client and friend of mine hand some luck with Mr Hollowpoints 456 260g and the HAH 453 261gr. So far he is liking the Mr Hollowpoints best. I'll post here if I get any more feedback from others.
I am still getting used to holding the gun honestly. I had the Bushbuck 45 for 5 years and when I first got it I would group 6" at 100yd, and by the end I could get a small 1-2" group over 5 shots. The difference was that I learned how to hold the gun properly, so I believe with a bit of practice the Rattler groups can get better. The other thing I need to invest in is a better sand bag with a bit more elevation.
If anyone finds a good bag for comfort or some other method, post it here!