TC introduced a significantly redesigned liner several years ago now which is extremely fast...attributes are:
Heavily coned inside, and has about a .030" thick divider wall with a large hole about 5/64" size...can almost start a 5/64" drill bit into it but not quite...I think a #70 drill bit will just make it in. The outside also has a very large cone effect because of the "well" created by the design to use a hex wrench instead of a screwdriver.
Furthermore, there is additional performance design detail in these liners...the very outer edge of the top of the hex well has a 45* angled bevel all around it to collect as much heat pulse as possible...then at the very bottom of the hex well, there's another 45* bevel that further funnels the heat pulse into the hole itself.
And finally, there's a flared edge or collar that seats up tight agtainst the breech plug material around the threaded seat in the plug which serves as a positive stop so the depth of the vent is at the same place every time it's removed or cleaning and reinstalled...may add an additional element of sealing too.
My best way of describing the design improvements TC made to its lock and vent liners in the '90s. is that with Goex 4F prime & 3F main, the new lock, and the new vent...it's like shooting a .30-30.
And I don't know if its a result of the patent breech design, or the redesigned vent liner, or both, or neither, but the vent is what I'd call self cleaning...don't own a vent pick, never use one.
The combination of the above components result in excellent ignition and there are just no failures...I have yet to have a single misfire or problem related to equipment...any misfire I've ever has been operator error only.
