what is a gas check?

snowy1

I am new at reloading and I am seeing auctions for "gas checks" and wanted information on what they are and how or when they are used....Thanks....Snowy1

nononsense

snowy1,

Gas checks are a metallic cup applied to the bottom of lead bullets to protect the base from the hot gases produced by burning gunpowder.





Best.

mbsams

To add -- they are said to improve accuracy for supersonic lead loads - or the hotter lead loads - not needed for normal lead target loads under 1000 fps or so.

B17-P51

To add, gas checks are attached to the base during the sizing operation, or by the same process without sizing if the diameter is ok. I say this because there is some confusion occaisionally on this forum as to the method of attachment. They are not glued or simply pushed on. As NONONS' post shows they are crimped on amd usually will stay on through the firing and impact phases and can often be found still on the cast bullet. Nonons post also shows the gas check when seated is slightly larger than the bullet diameter. This is incorrect as it it the same size through the crimping operation. When you recast the same lead they will float to the top but cannot be reused.
They allow for higher velocities by keeping the base of the bullet from melting and also impart a sort of "scraping action" (for lack of a better term) to the barell to reduce leading.
The bullet as cast must be of the type that will accept a gas check, that being the base is smaller than the body and usually the mold # is preceded by GC.

jonk

To add to B17's comments, SOME gas checks DO just push on- mainly the older style lyman and ideal kinds. They are designed to fall off upon exiting the barrel.

B17-P51

thanks JONK never used that kind!

swagg68

From what I can tell from my readings a gas check as shown in the second response is not necessary for 9mm. I just purchased a Lee bullet resizing tool and it indicates by adding a lubricant to the newly cast lead bullet and pushing it through the resizer it will seat gas checks. Does this sound right?

MMOMEQ-55

Here are a couple of gas checked bullets. The copper base is the gas check.

partisan

I can personally attest that gaschecks are most definately needed if you shoot .44 mag cast bullets. I learned the hard way.

swagg68

Is it common to use gas checks on light loaded 9mm?

melkor

Its when U smell after a fart[:D]