I am going to be machining my own breechplug from a blank casting. 58 caliber bore, 3/4 patent breech/snail type plug. How big to make the patent breech chamber, and how much coning to do? How big to make the flame channel? Thanks in advance for any help given. I am sitting here planning this out since it is too cold right now to use the lathe!
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Breechplug
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Erzulis boat
45 Cal.
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On the hybrid rifle that I built, the "snail" breech was threaded 5/8-18, and the internal "cone" was done with a 9/32 ball endmill on the lathe in a 4 jaw chuck at 115 rpm.
Depth of penetration is dictated by the channel from the nipple cavity into the "chamber".
The drill diameter should be within the span between .1065 (small) to .144 (large), as this is the span I have seen in working configurations thus far, of course, there has to be variances beyond this span, but this is just what I have seen.
The hole connecting the nipple allocation and the "chamber" is drilled at an angle to intersect at the target location. Put the breechplug in a vise on the drillpress if you can.
I drilled the connecting hole to intersect the 9/32 diameter chamber at the base, and if I run a pipe cleaner through the channel, the "fuzz" of the cleaner will brush against the rearmost curvature of the semispherical 9/32 diameter chamber.
With the 5/8-18 breechplug (.700" thread penetration) a 9/32" diameter "chamber" will have no ill effects. The chamber (if memory serves me correctly) was about .400" to .450" deep.
If the breechplug was 3/4" (threaded portion) a 5/16" ball endmill would be fine.
These figures represent a very safe setup, you could go larger in all directions, but I do not think that it is required.
Depth of penetration is dictated by the channel from the nipple cavity into the "chamber".
The drill diameter should be within the span between .1065 (small) to .144 (large), as this is the span I have seen in working configurations thus far, of course, there has to be variances beyond this span, but this is just what I have seen.
The hole connecting the nipple allocation and the "chamber" is drilled at an angle to intersect at the target location. Put the breechplug in a vise on the drillpress if you can.
I drilled the connecting hole to intersect the 9/32 diameter chamber at the base, and if I run a pipe cleaner through the channel, the "fuzz" of the cleaner will brush against the rearmost curvature of the semispherical 9/32 diameter chamber.
With the 5/8-18 breechplug (.700" thread penetration) a 9/32" diameter "chamber" will have no ill effects. The chamber (if memory serves me correctly) was about .400" to .450" deep.
If the breechplug was 3/4" (threaded portion) a 5/16" ball endmill would be fine.
These figures represent a very safe setup, you could go larger in all directions, but I do not think that it is required.
Thanks!
Using less than perfect tools to check since the calipers are in the garage and I am staying in the warm house, this is what I have. The patent chamber will be right at 1.3 inches long if it comes to the back of the nipple channel. From the nipple to the patent chamber will be about .5. If I use a 5/16ths mill to cut the chamber, would you also cone the top of the plug, and if so, how much. Again, thanks in advance for any info you can share!
I could also mill the snail off and make it a flinter!
Using less than perfect tools to check since the calipers are in the garage and I am staying in the warm house, this is what I have. The patent chamber will be right at 1.3 inches long if it comes to the back of the nipple channel. From the nipple to the patent chamber will be about .5. If I use a 5/16ths mill to cut the chamber, would you also cone the top of the plug, and if so, how much. Again, thanks in advance for any info you can share!
I could also mill the snail off and make it a flinter!
Erzulis boat
45 Cal.
- Joined
- Jul 14, 2005
- Messages
- 566
- Reaction score
- 78
I did "cone" the face of the assembly with a 90 degree cutter. The cone was opened up to about .450" or so (at the outer perimeter).
I also ran the channel at a forward angle from the base of the 1/4-28 nipple receptacle.
The angle was the maximum allowable that did not allow the drill to impact the threads in the nipple receptacle.
I also took a flat faced counterbore with a pilot and created a uniform seat for the flange of the nipple.
I also ran the channel at a forward angle from the base of the 1/4-28 nipple receptacle.
The angle was the maximum allowable that did not allow the drill to impact the threads in the nipple receptacle.
I also took a flat faced counterbore with a pilot and created a uniform seat for the flange of the nipple.
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