Oops, it looks like I screwed up on the 10.5 gr group.  I missed the one low down so that group is significantly worse then the 2.41" I posted.  I appear to have had a flyer.  Well, in my defense, THE SUN WAS IN MY EYES, lol.

What did happen I think was the previous group was only a 4 shot group since I had a misfire on the fifth so my mind decided the next target was also a 4 shot group.

I tried out some loads with longshot.  To make a long story short, 7.8 gr longshot seemed to give the best group (4 touching and then a flyer 4 inches away, LOL).  Speeds were 1361 fps on average for the 180 gr fmjfp from RMR.  I tried another group with the 217 gr cast lead hp bullets from GT bullets but got the same result as last time.  They are all over the place.  Only 2 out of five even hit the 6 " target and they were 4" apart.  I took the barrel off and looked down it to see if I could see leading but it looks clean.  I don't know what the deal is.  Maybe I am trying to load them too hot.  This is a blowback action so maybe the chamber is opening too early with the high pressure.  I did a little experiment with the longshot to see if hotter loads had more of a spread in velocities and it was inconclusive.  7.3 gr longshot had a 41 fps spread for 5 shots while the 7.8 gr loading with the same bullet only had a 23 fps spread.  Maybe it is an issue with cast lead bullets versus jacketed.  Maybe I will get some heavy cast lead flat points and load those with a variety of charges and see if I can make cast lead work.  If I can do that, I will pull some of these HP bullets and reload them with charges that work for the other cast lead and see if they will fly.  If I can't get good hot loads to work with heavy slugs, maybe I should just go 460 Rowland.

I like the idea of the .460 Rowland. I prefer Magnum type loads and believe that would fit the bill for me. It's been a couple of years since it caught my interest, I think the cost of the conversion has me stopped. The brass and reloads don't bother me a bit.

It depends on your firearm of course but it is pretty cheap for the TNW ASR.  Just a few hundred dollars for the 460 Rowland conversion kit (barrel and bolt).