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Gunsmithing Howa bolthead from 308 to 6.5PRC?
- Thread starter DWilson
- Start date
The challenge is going to be the extractor. -maybe...
To go from .48 to .545 pencils out to around .032" radial increase. Simply to mean the extractor needs to be that distance further away from the center of the striker pin hole. Depending on how Howa does their extractor claws, this may or may not work. You have to think about how the case gets "behind" the extractor claw.
The angled face of the extractor encourages the case to push it away from center using the forward motion of the bolt to do the work once the case connects with the shoulder of the chamber. Most extractors have a flat/blunt feature on the face along the outer periphery. If the case rim is larger than this radius, it won't slip over no matter how hard you try. Everything just stops and you cannot get your bolt to close.
So, lets say this is solved somehow. Now you have to work on the spring. Most M16 type extractors have a fairly short range of movement. This is usually limited by the spring. The coils begin to stack on top of one another. "Coil bind" is how this is often described. The M16 xtrs I've used have a 2:1 ratio in regards to length and location of the pin. So, if were moving .032" farther we can expect the spring to compress an additional .016". The pocket the spring sits in may need revision. Easy enough so long as we don't run into the hole the striker sits in.
The other issue here, although fairly minor, is the channel feature the extractor resides in. If the case rim is .032 further away from the center, the channel should also be lifted accordingly. Cascading with this is the pin's hole location. It's all related to one another.
Not saying it cant be done, but whoever does it needs to have a very good understanding of how all this stuff works.
Good luck.
C.
To go from .48 to .545 pencils out to around .032" radial increase. Simply to mean the extractor needs to be that distance further away from the center of the striker pin hole. Depending on how Howa does their extractor claws, this may or may not work. You have to think about how the case gets "behind" the extractor claw.
The angled face of the extractor encourages the case to push it away from center using the forward motion of the bolt to do the work once the case connects with the shoulder of the chamber. Most extractors have a flat/blunt feature on the face along the outer periphery. If the case rim is larger than this radius, it won't slip over no matter how hard you try. Everything just stops and you cannot get your bolt to close.
So, lets say this is solved somehow. Now you have to work on the spring. Most M16 type extractors have a fairly short range of movement. This is usually limited by the spring. The coils begin to stack on top of one another. "Coil bind" is how this is often described. The M16 xtrs I've used have a 2:1 ratio in regards to length and location of the pin. So, if were moving .032" farther we can expect the spring to compress an additional .016". The pocket the spring sits in may need revision. Easy enough so long as we don't run into the hole the striker sits in.
The other issue here, although fairly minor, is the channel feature the extractor resides in. If the case rim is .032 further away from the center, the channel should also be lifted accordingly. Cascading with this is the pin's hole location. It's all related to one another.
Not saying it cant be done, but whoever does it needs to have a very good understanding of how all this stuff works.
Good luck.
C.
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