VENT LINER

[Gemoke]

Will coneing a vent liner help with ignition or will it cause a problems.
cut finger

 

[Black Hand]

It will probably help, as it puts the powder closer to the pan and the spark has less distance to travel. Ignition speed may also be affected by the size of the touch-hole as well.

 

[Java Man]

I opened the TH on mine to .078". :winking: Noticed the flash hole was kind of thick. I might slightly cone it as well on the outside.

 

[J.D.]

I assume that you are talking about coning the outside of a liner? Coning can increase ignition speed and reliability, especially if the liner has a screwdriver slot.

Cone the outside of the liner just enough to give a smooth cone through the depth of the screwdriver slot.

Opening up the touch hole a bit can help too, depending on the caliber. As a general rule of thumb, for small bores, a .062 TH is probably best. .068-.073" diameter TH's work well for 45-50 cals and larger.

Use a set of letter drill bits and drill the TH in small increments of .003, or so, and test fire 20-30 shots to see if there is any improvement in ignition before drilling the next larger size.

J.D.

 

[Black Hand]

My liner is coned on the inside, installed, and filed flush before browning the barrel. After-market intstallation may require a bit more work.

 

[Java Man]

My gun is a 20ga, and I'm shooting 2F.

 

[Larry Pletcher]

I timed vent holes for a MuzzleBlasts article in the Feb 2000 issue. A mild exterior cone improved the time by a small but measurable amount. At the end of the article I concluded that a no. 50 bit (.070) or a 5/64 bit(.078) with an exterior cone would be my choice. The cone i used was mild - a spun the counter sink by hand.

Regards,
Pletch
(Larry Pletcher, Indiana)

 

[Herz_aus_Stahl]

My TH is coned on the outside and 1,8 mm(.070) wide (.54 Jaeger). Its really fast.