gas checks?

[darat100]

Can someone please explain to me what a gas check bullet is and the purppse.  what are the pros and cons?

thanks

[Cowpox]

A cast lead bullet with a short (1 1/0th inch or so) cup of jacket metal crimped on the base. It is best to use a mold cut for casting bullets with the recess on the base where the check fits on before sizing.  The pro is, they let you drive cast bullets in a rifle with less lead buildup in the bore. the con is, I have a hard time getting them on straight. I gave up, and went to the "half jacket", which is basicly the same thing, only much longer, and easier to put on the bullet correctly.

[stuffit]

Here's a picture:

The check is gilding metal or copper.  If the "gas check shank" of the bullet is the correct size, the gas check should crimp on when the bullet is sized and lubed.  There are an assortment of notions about what good effect the checks have.   I think the "protect the bullet bases from the hot powder gases" is over done, but it likely does that to a degree.  It also (again my thoughts) acts as a sort of a rear copper driving band and often provides better stability and accuracy.  Copper is getting more expensive now and that's the main downside of the equation to my notion.  Installing the gas checks on the bullets does involve an extra step or two but worth it for the improvement in performance, i think.  Depends on how much of a hurry you're in, I reckon.
 
stuffit