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nulreference 11-12-2013 01:19 AM

Considering custom DIY bolt receiver
ok im considering doing a custom bolt reciver and i cant find a real answer to a burning question i have.

why are all the raceways on everything Squared off? (attaching picture)

assuming everything else being equal as far as bearing surface area for the lugs
would a rounded profile work? like i said attaching picture

either i just found a much easier way to do the receiver (bolt will be a bit harder but meh) or im missing something and thats why im asking

JayCody 11-12-2013 01:42 AM

From what I understand the reason it is squared is so the bolt lugs lock into the chamber lugs securely. I may be wrong but almost all rifles are made squared. There must be a good reason.

nulreference 11-12-2013 02:16 AM

yes but is that reason something like.

well its always been done that way so why change

and for major gun manufactures this makes sense why rock the boat they can afford to do it the way its always been done.

might have to make the rounded one and test to see of there are any issues

clr8ter 11-12-2013 02:31 AM

OK, so I have to ask……why are we supposed to assume the rounded raceway has the same total area of the squared one? They don't.

Given that the square one is the same size as the round one (ex. a .250" square, and a .250" diameter round), the square one has to have more surface area.

hiwall 11-12-2013 02:32 AM

The rounded ones are fine and have been used but locking faces of course have to have square profiles.

nulreference 11-12-2013 02:55 AM

by that i ment assume the rounded one is larger so the profile area is the same

and locking faces being square im assuming you mean where the bolt lugs would engage the reciver lugs being flat faced front to rear and yes figured that would need to be or the bolt could blowback and jam itself in there

SSGN_Doc 11-12-2013 03:24 AM

If you were to do that and lose some bearing surface, why not make three lugs and space them out evenly around the bolt. You would also reduce bolt lift and thus speed bolt action while spreading the load agains the lugs more evenly around the bolt.

hiwall 11-12-2013 12:54 PM

1 Attachment(s)
Look at pictures of the Weatherby Mark V bolt.

nulreference 11-12-2013 01:23 PM

my goal is to reduce the need for complicated machining tasks.
and a 3 lobed bolt would work as well

I'd like a pattern anyone wit the mechanical aptitude to run a lathe and a mill/drill can make with a minimum of fus in a SHTF type of situation or just because they want to get into the making of prototypes

clr8ter 11-12-2013 04:31 PM

OP, would you care to share what your end goals are? I'm confused. If SHTF, I'm pretty sure making firearms from scratch is going to be the least of your concerns, and a fair distance outside anyone's capabilities.

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