I'm not a person inclined to "leave well enough alone". (However, I do believe strongly in "Don't fix what ain't broke".)
I'm also not stupid or foolish. (I have made it to 64 with all my parts and faculties in spite of starting to reload when I was 16, and starting to making rifles when I was 50.) So...
While building another AR-10-based wildcat (this one chambered in 8mm-08), I came to some understanding that one doesn't usually get if one simply "assembles factory parts". One of tidbits of information that 'came' to me was that the bolt actually locks up "in" the barrel, not the receiver. Of course it's not really the barrel in a technical sense, but since the barrel extension is conceptually the "barrel", the bolt does lock up in the barrel.
That illustrated clearly that the barrel nut does NOT have to 'hold' any of the pressure generated by the firing of a cartridge. (Probably. I'm still mulling over the "push me/pull you" of the bolt lockup/barrel extension assembly.) However, that realization quickly lead to "What if the barrel nut did in fact "hold" the pressure"?
There is more to the question that simple curiosity. I was considering, (but abandoned at this point), making what is essentially a 'Savage-type' barrel attachment mechanism on a milsurp Mauser action - (Turk '38). However, unlike the Savage, the idea was to make the barrel stub 'slick' and cut a flange (slick and flanged like the barrel extension on an AR); thread the OD of the Turk rcvr to accept an AR barrel nut (1 7/16"-18); slip the barrel in the rcvr, screw on the barrel nut and matching handguard, and achieve what I want which is a completely cantilevered barrel. Thinking that process through is what got me to the realization of "in-the-barrel-lock-up" which then lead to "Uh oh, the barrel nut threads are going to have to 'hold' the barrel on, and I don't think that's 'good'". I suspect that Savage's barrel nut attachment assembly maintains the threaded barrel BECAUSE the bolt does not lock up IN the barrel, but that's just speculation on my part. It could simply be for "lawyer" reasons.
Considering all of the several factors involved, I have essentially abandoned the idea for the Mauser receiver. Even making a custom, steel "barrel nut" does not give me sufficient confidence that the fundamental design is sound in the context of STRENGTH. HOWEVER, I CANNOT FIND THE SPECS TO PUT THAT IDEA COMPLETELY TO REST AND I HATE "GUESSING". So I come here asking for information on:
1) the tension strength of the "screw joint" between the barrel nut and upper receiver specifically, and
2) the tension strength between a 1 7/16 - 18, STEEL thread (like the aluminum receiver of an AR-10), and its mating female STEEL nut, (like the aluminum AR-10 barrel nut).
Here's another important detail: The steel-on-steel joint would only get 0.5" of that 18-pitch thread.
Let me make some things clear:
1) Spare yourself the trouble of advising me not to do this for "safety's sake". I have no intention of "doing" this at this point. That does not change my curiosity about the strength of the joint, AND it does not show me where to go to get the information I need.
2) Spare yourself the trouble of advising me about the "inherent weakness" of Turk '38 Mauser actions. I know better from considerable personal, first-hand experience.
My real interest is in finding out just how strong the "connection" is between a "real" AR-10 upper and the barrel nut; how much stronger that connection would be if it were steel on steel instead of aluminum on aluminum; and where I can go to either find the information in a table, or calculate it.
Thanks in advance,
Paul
I'm also not stupid or foolish. (I have made it to 64 with all my parts and faculties in spite of starting to reload when I was 16, and starting to making rifles when I was 50.) So...
While building another AR-10-based wildcat (this one chambered in 8mm-08), I came to some understanding that one doesn't usually get if one simply "assembles factory parts". One of tidbits of information that 'came' to me was that the bolt actually locks up "in" the barrel, not the receiver. Of course it's not really the barrel in a technical sense, but since the barrel extension is conceptually the "barrel", the bolt does lock up in the barrel.
That illustrated clearly that the barrel nut does NOT have to 'hold' any of the pressure generated by the firing of a cartridge. (Probably. I'm still mulling over the "push me/pull you" of the bolt lockup/barrel extension assembly.) However, that realization quickly lead to "What if the barrel nut did in fact "hold" the pressure"?
There is more to the question that simple curiosity. I was considering, (but abandoned at this point), making what is essentially a 'Savage-type' barrel attachment mechanism on a milsurp Mauser action - (Turk '38). However, unlike the Savage, the idea was to make the barrel stub 'slick' and cut a flange (slick and flanged like the barrel extension on an AR); thread the OD of the Turk rcvr to accept an AR barrel nut (1 7/16"-18); slip the barrel in the rcvr, screw on the barrel nut and matching handguard, and achieve what I want which is a completely cantilevered barrel. Thinking that process through is what got me to the realization of "in-the-barrel-lock-up" which then lead to "Uh oh, the barrel nut threads are going to have to 'hold' the barrel on, and I don't think that's 'good'". I suspect that Savage's barrel nut attachment assembly maintains the threaded barrel BECAUSE the bolt does not lock up IN the barrel, but that's just speculation on my part. It could simply be for "lawyer" reasons.
Considering all of the several factors involved, I have essentially abandoned the idea for the Mauser receiver. Even making a custom, steel "barrel nut" does not give me sufficient confidence that the fundamental design is sound in the context of STRENGTH. HOWEVER, I CANNOT FIND THE SPECS TO PUT THAT IDEA COMPLETELY TO REST AND I HATE "GUESSING". So I come here asking for information on:
1) the tension strength of the "screw joint" between the barrel nut and upper receiver specifically, and
2) the tension strength between a 1 7/16 - 18, STEEL thread (like the aluminum receiver of an AR-10), and its mating female STEEL nut, (like the aluminum AR-10 barrel nut).
Here's another important detail: The steel-on-steel joint would only get 0.5" of that 18-pitch thread.
Let me make some things clear:
1) Spare yourself the trouble of advising me not to do this for "safety's sake". I have no intention of "doing" this at this point. That does not change my curiosity about the strength of the joint, AND it does not show me where to go to get the information I need.
2) Spare yourself the trouble of advising me about the "inherent weakness" of Turk '38 Mauser actions. I know better from considerable personal, first-hand experience.
My real interest is in finding out just how strong the "connection" is between a "real" AR-10 upper and the barrel nut; how much stronger that connection would be if it were steel on steel instead of aluminum on aluminum; and where I can go to either find the information in a table, or calculate it.
Thanks in advance,
Paul