As far as I know there is only one way to gas check a plain base bullet, that is home made aluminum (or other similar thin material) checks. All commercially offered checks that I know of require a rebated base on the bullet because of the check thickness.
Some work...some don't. I made my own " pop-can check cutter" (from plans offered on CASTBOOLITS, lots of info on this subject on there) and have had mixed results so far.
I am ordering some "powder coating" powder this morning to give that a try myownself. I have read some testimonials that claim powder coated bullets have replaced "checked" bullets and have been shot at almost jacketed bullet velocities. I won't be shooting any of my Boolits at that type of speed but still enjoy playing with new ideas at moderate velocities.