Because of popular demand we provide aluminum gas checks to fit plain base bullets that were not made with a gas check shank. We mainly make these from lithographic plate that is .008 to .012 thick depending on caliber. The initial requests came from the 10mm users over on Glock Talk, since then we have been expanding the calibers. These allow reloaders to push their wild cat 45's and hot 10mm's much faster with less barrel fouling. If you have a 45 mold without a gas check shank, you can use the .452 plain base gas check for .45 Colt, .454 or even .460 loads and get the benefit of a gas check.
These are thin gas checks made to just cover the bullet base enough for a decent crimp. It's best to run these through the sizer base first. A good solid and even seat is critical, the plain base gas checks must be fully seated before sizing.
While testing the plain base gas check using a LEE push through sizer we found that some of the LEE sizing dies have a rough ring inside the mouth area. A simple smoothing of the mouth allows for much better results with the thin gas checks. One simple way to remove the rough area is to use a die grinder stone. Here in the US a cheap kit can be found at Walmart, near the air tools. They have a small kit with a cone shaped stone that can be used in a variable speed drill or a drill press. I takes very little effort to remove the rough rings. We haven't seen the rings in other dies so far, the issue is only with some of the LEE sizing dies we have used.
Here are some additional remarks about Plain Base gas check sizing:
The PB gas checks can be tedious to use, it depends on how tight the sizing dies are. When using PB gas checks the bullets can be beveled slightly to help with getting them on evenly. The PB gas checks have to be very thin to work, so the sizing die must be completely smooth. The bases need to be clean and even, the gas check needs to be fully seated.
We use polished Lee push through sizing dies for PB gas checked bullets. A simple smoothing of the sizing die mouth allows for much better results. Sometimes you can just polish the dies a little with coarse and then a medium polishing compound on a cone shaped felt polishing bit. We use valve lapping compound like you find at auto parts stores. Use a very light lube, I use a shot of WD40 in the die. Run the PB bullets through the Lee sizing die base first.
Harbor Freight has a cheap "dremel tool" kit for polishing. We use the tapered felt bits in a variable speed drill. Some guys use a wood dowel of the right size and fine grit sand paper. Ebay has tapered felt polishing bits in various metric sizes like 8 mm, 10 mm etc. McMaster Carr is also a good source for polishing items. A simple cotton mop of the right size with polishing compound chucked into an electric drill will also work.
One customer actually chucks the die in his mill and uses sand paper, that will work if you have a drill press with a large enough chuck too. It may be easier to use a small die grinding tool like a variable speed dremel or just a regular drill and put the sizing die in a vice. Occasionally the gas checks may go on without any trouble with some older sizing dies, but we usually had to do some honing or polishing.