"Gas-check" coatings

[Newtire]

Maybe I am just off on the wrong track or not but I always have heard that the gas check's purpose was not to prevent the boolit base from melting but to keep the bases uniformly flat under the pressure of firing or something along those lines.

I read where the short trip down the barrel of even a long barreled Mosin Nagant (for instance) and the time involved wasn't enough to heat the boolit base up to cause any actual melting.

It said (wherever I read this?) that the flat surface of the check helped to give a more uniform platform for the pressure to have a chance to make the boolit obturate and seal the bore.

So, this is not straight from the burning bush on top of Mt. Galena but seems more logical than the heat theory. Just a thought.

[BluesBear]

It's not so much that the lead actually melts, because it doesn't. Examination of recoverd fired boolits will confirm that. If the boolit had actually melted the base would become a glob.

What the gas check really does, is attempt to prevent erosion of the base by the hot, high pressure gases pressing against it.
Like any high pressure gas, the gasses from burning gunpowder are looking for an escape route.

The gas check actually deters obturation of the boolit.
This makes proper sizing of a gas check boolit every bit as critical as a plain base one.

[maximus]

I was thinking on EZ-SLIDE ALKYD GRAPHITE COATING since graphite melting point (3700 or 4000 K), it may work , i dunno test it in 9mm first lol then go up!

[leftiye]

No, the lead doesn't melt. But I think it gets a lot softer. Virtually all deformation that causes inaccuracy could (can) be caused by "soft" lead - maybe caused by heat. Look at how paper patching changes the situation!

[maximus]

i have tryed graphite oil, it worked fine, but very mokey.

[Jim]

In the beginning of this thread, it was mentioned that keeping the heat off the base of the bullet is the trick.
Back in the spring, there was a thread going on(for a looong time) about shooting boolits at some incredible speed like warp 9. The poster wrote that he used plastic shot shell buffer over the powder to create a barrier between the powder and the boolit and it also created a false 100 percent case density.