Originally Posted by
ronlaughlin
sabotloader
Well, i guess it is a good thing the 25/64 drill will work, because it doesn't appear that a 40* end mill is readily available. Seems to me that it would be best if the rim of the vent liner made first contact with the breech plug. Like you say, i can make that happen by grinding the drill to a steeper angle than 30*. Seems that if the angle were ground too steep, it would be better than if it were too shallow.
I guess i will start the modification before the vent liners arrive, by drilling out the fire channel with a 5/32 drill, then when i have the vent liner in hand i can drill again, and through with a #21 drill. Doesn't seem as though it will be much of a problem. Time will tell.
Your drill will work fine, The taper on the Savage style vent liner screws is listed as 82* . You can geta 82* countersink, this is what I finish my holes with now. The reason for the 25/64 drill is the average head diamater of the vents is 3/8" + 24/64. Some are smaller. I shot my rolling block over 400 times before I got the 82* countersink. You will be fine.
As a point of interest, the original ML10 that uses the modules also uses a vent liner, but this vent is made from a 10/32 set screw, these have no head as a screw does.
I make my own vents fro 10/32 x 3/8 Holo Krome screws, these are the same screws as the OEM savage and most of the aftermarket suppliers use. I drilled 28 last week, I got Cobalt drills for this. I start the holes using a .062 Cobalt drill This is to get threw the hard surface of the screw on both ends, this is what will break the .0315 cobalt bits. I use the .062 from both ends then finish the hole with a .0315 cobalt drill . I am still using the origonal .062 drill but have only been able to get 14 screws out of the .0315 bits. 14 is my best so far. I do use my lathe to bore these but there are many that use a drill press.
I have not tested the Leighi style vent screw yet . But my next purchase of a box of 100 screws will be with the doomed head.
There is no reason that the plugs can't be reworked with just a drill motor! Clamp you plug securely and drill as straight as you can.
It has been proven on other boards/ groups that a crooked hole in the vent liner will not effect it's performance!!! Have you ever really looked at the flash hole in a lot of brass cases. Oem Vents from savage will not always be centered.
With that said have at it!
One of the things I live by is:
"God hates a coward, but is very tolerant of fools!"