I think Lady Luck is laughing at me these days

I have been trying to get my guns finished and ready to go for the lion hunt in a little over 2 months. The problem is I have to get my paperwork finished and ready to send off in this next week, which is normally no big deal. And I have my 3 guns listed on there that I plan to take. My main problem is my 510 GNR. The gun has been a great gun for years. It has been to Australia, several South African hunts, Alaska, the Celebrity Handgun Hunt and other places I can't remember. The gun has always been perfect, always dead on and seldom did I need a second shot, and if I did it was my fault. Now for the hunt and thinking of possibly needing a couple of shots quick I put a new barrel on it with a muzzle brake to make the 8" length required for the handgun rules over there. But now it scatters the bullets all over the target. Still a 5 inch group but I need that 1 inch group for this hunt. We have worked for 3 days on this gun, replacing everything and starting over a couple of times and still no go. I can't just drop the idea and start over with the other 2 guns on my list as I have this gun listed as coming with me.

My other 2 guns, the custom Encore in 378 GNR and the custom Bad Medicine revolver in 429 GNR are doing fine. But with a 600 lb pissed off lion at 20 yards thinking of having me for lunch I would really like to have my 510 GNR in my hand. Normally on hunts that have bad news coming at me or possibly coming at me, I take the first shot with the 378 GNR then if the critter is still standing, the 378 gets tossed and I pull the 510 GNR out of it's crossdraw holster and depend upon that. Now I don't feel that I can depend on the 510 GNR. So while you guys are munching on hot dogs and cole slaw tomorrow I will probably be up here having a long talk with my 510.We have to come to some understanding or else.