Never been a gas check fan... This is my first GC mold in fact... To many respected shooters speak up for them these days to not try them for higher velocity loads... Beware the heavy bullet in the 41... The 265 is pushing the limit for the stock Ruger and S&W 41 mag twist rate. Your chances are better with the 250... I plan to run this 265 out of a Custom Ruger using a Maximum cylinder trimmed .2 inches, a S&W 18 twist barrel, and the 1.6 inch 414 Supermag case trimmed to 1.4....
Now... If you have a FA 41 mag you have a 14 twist barrel and you are good to go with the 265 and heavier bullets..