Gas Checked

[Deerslayer]

I'm new at reloading and I keep reading bullets are gas checked. Can someone please clue the green horn in on what this means ?

[Rojo27]

Short answer:
Gas checks are small cups or disks of copper or other alloy, attached at base of non-jacket (cast) bullets to be fired from a high pressure cartridges which helps reduce leading in the barrel.

More complete answer:
http://en.wikipedia.org/wiki/Gas_check

[sqlbullet]

Rojo covered the main points.  Basically it is a base jacket.



They will become relevant to you once to enter the next phase of depravation:  bullet casting.

You will find many opinions on whether or not they are needed on 10mm Auto cast bullets.  The honest answer is "It depends".  And the flowchart to answer that question is in reality insanely complex.  The best course of action is either to always use them in 10mm, as properly fit they won't impede performance, but will increase cost, or to start without them and carefully look for signs of leading that can be corrected with a gas check.

I personally don't gas check any of my 10mm cast bullets.  I DO deal with leading from time to time, but so far I have been able to correct it via other means.  That does not mean my opinion is there are not situations where a gas check is not the best way to correct a leading issue, or another performance issue.

I certainly do gas check the cast bullets I shoot in 30-06 and 300 win mag.  I have read of guys with ideal situations that get away with plain base bullets in 30-06 with carefully constructed loads, even at speeds above 2000 fps.  And I believe the reports.  But you will find that it is one very specific load and gun combo that they worked often for years to develop.  Since I reload more to shoot, than the other way around, I am not interested in those kinds of load development timelines.

[The_Shadow]

Here is a Double Tap 200gr Wide Flat Nose Hard Cast Gas Checked, see the small copper cup to protect the base of the bullet from the hot high pressure gases that would start to bypass thus leading the barrel. 



Underwood 220gr Hard Cast without a gas check.



When using cast bullets several things play into whether they will work well without leading of the barrel.  Size is the most important part, bullets need to be 0.001" at the minimum larger than the bore of your gun and some work even better at 0.002" over bore diameter.  The hardness has a function to allow the bullet to engrave the rifling without it sliding much and strong enough not to be eroded by the hot high pressure gases, but not so hard that the base doesn't obturate.   Another very important thing is lube, this serves several functions, lubricate the bore surfaces so lead deposits don't frictional stick being most important, leaving a slight film for subsequent shots.

[Deerslayer]

Thanks everyone. I know what your talking about now. My guess of what it was wasn't even close to what it is. lol

[The_Shadow]

I haven't gas checked any of my 10mm bullets sized at 0.4015", I do gas check 357Mag, 44Mag and my rifle bullets.
As the prices for the gas checks rise I am using them less and less.

[ShadeTreeVTX]

I don't gas check any of my 10mm loads either, but I have converted over to powder coating all my cast heads and no trace of leading what so ever.

Doug