Vent hole location

[Dennis Daigger]

I got my White Lightning liner in and the hole is located 7/32" in front of the breach plug face.  Does that create an issues with ignition or pressure consistency that the charge generates?  Pretty obvious that the fire gets started somewhere other than the very rear of the charge.
Dennis

[Mr. Bubbles]

No not really.  The fire will be burning in 2 directions fanning outward from the touch hole, rather than in just 1.  Only if you drill a TH to land right on the face of the plug will it burn that way.  Obviously with a hole higher than that, you have to make sure you load enough powder for it to be lit.  I guess it would make for slightly higher initial peak pressures, but no enough of a difference to lose any sleep over.  Now if you took it to the extreme, moving 4-5-6 inches up the barrel, and the top of the powder column were double that distance you might have an issue.  But if you did that you would probably already have a Darwin Award, so the point is rather moot.

[M. E. Pering]

Sounds like it is well positioned to me.  That should be safe with just 15 grains of powder, unless you have a huge caliber.  My latest creation has the liner 1/8th ahead of the plug face.  I will post the pics when it is finished.  Keep in mind, that the further to the rear you put the hole, the more crevasses you are likely to create for fouling to hide, and thus deteriorate the barrel.  I think your positioning is just fine.

Matt

[Dennis Daigger]

Thanks, Mr. B and Matt.  I didn't think to check before but did yesterday and a 75 grain charge is a 1" column in the barrel so should be ok.
Dennis

[D. Taylor Sapergia]

When I plan for the installation of a White Lightning liner, I measure the diameter of the thread journal and place it in the barrel so that the journal just about kisses the breech plug face, but not quite.  For example, a 1/4" x 32 liner's vent hole would be 1/8" + a few thou forward of the face of the plug.  That way, there is no interference with the liner and the plug.

[Dennis Daigger]

When I plan for the installation of a White Lightning liner, I measure the diameter of the thread journal and place it in the barrel so that the journal just about kisses the breech plug face, but not quite.  For example, a 1/4" x 32 liner's vent hole would be 1/8" + a few thou forward of the face of the plug.  That way, there is no interference with the liner and the plug.

Thanks for the response.  Looks like mine shouldn't be a problem as it is only 3/32" more forward than yours.  As Matt suggested 15 grains of powder would be about even with my vent hole.
Dennis

[flehto]

When using the 1/4-32 WL liner, the TH is placed 5/32" ahead of the plug face.  On my  squirrel LR the TH  in a home made 1/4-20  liner is 9/32" from the plug face and works just fine and the thought arises that perhaps 9/32" prevents crud from filling the inside cone when swabbing which is really the hex recess of an Allen set screw.  Have used the 5/32" distance from the plug face because it's brings the breech  of the bbl closer to the lock fence. I think w/in reason, there's quite a bit of leeway when locating the TH......Fred