Steel rather than brass 10-32 threads (brass will eventually break).
Strongly disagree. Brass is kinder to your barrel. And, in my oft repeated 40+ years of doing this, I have never had, or encountered a brass tip or jag breaking. I have some as old as that 40+ years. Even wood and antler tips can last, and last and last and......
Here is another lecture. Many ranges and shoots under NMLRA rules will not allow loading from flasks. They are simply too dangerous. Yes, yes, I know, here comes the inevitable "Mine ain't blowed up yet." response. Flasks were designed for military use where speed was more important than life and limb. Hang your flask on the wall. Admire but don't use. The use of a separate measure is required on most ranges and common sense dictates the same even while hunting. (BTW, I just love the "yet" part.)
When I had my gun shop I often heard customers say a friend had recommended a flask. My response was "He must be sleeping with your wife." That got their attention. I explained that use of a flask could be fatal then 'friend' would have the customers wife to himself.