I have never used a gas check on any bullets I've reloaded. I'm going to start reloading the .45-70 in my Shilo Sharps within the next couple of weeks. Reading lots of information here, I rarely see a gas check load for the .45-70. I will be using smokeless powder at first may some Blackhorn 209.
I know what the gas check is, but what does it do? Obviously it is not needed for the .45-70 but would it help?