I shoot Zero 185 JHP with 4.7 grains of N310 and/or Solo 1000 in my GT 45. I also shoot the Atlanta Arms 185 JHP match ammo. All provide the same result and the gun has no problem with either.
I have tried Zero 185 LSWCHP with 4.1 grains of Solo 1000 and had problems similar to what you appear to be having. When using the Zero 200 grain LSWC with 4.1 grains of Solo 1000, I have no problems. Bullseye powder works the same at 4.0 or 4.1 grains.
What all that means to me is that you may have a recoil spring problem and not a magazine problem or issue. If you have the heavy spring, then the JHP loads are probably suited to that spring and a lighter LSWC load may not be, or because they works sometimes and don't work sometimes, perhaps you are on the very edge of the recoil spring's ability to function the gun.
Recoil springs (heavy, medium, and light) are available from Larry's Guns in Maine. They cost a whole lot less than magazines and don't require any tweaking.
Before you try to bend or tweak your magazines and end up ruining them at great cost, try load changes by finding loads for jackeded and SWC that work with whatever spring you have.
A friend uses the heavy spring (came with the gun when new) and uses 4.7 grains of N310 for 50 yards and 4.3 grains of N310 for 25 yards. He also uses Solo 1000. He has no problems with those loads and his GT-45. His scores are high master level.
I noticed the Richmond location. Bring your GT 45 to the Cavalier 2700 on March 7th and I will bring extra ammo that I use in my GT 45 for you to try.