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Post by Deleted on May 19, 2014 21:15:09 GMT -5
50 is more than what I'll shoot anyway.....Everybody be safe....
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Post by edge on May 20, 2014 5:26:32 GMT -5
We all have custom barrels but not all have lugs on there bolts. If you trust the set screw holding the bolt on the 700ML for 78gr IMR4198 that's cool. It's not me pulling the trigger. The barrel is designed to contain the radial pressure and the BP to contain the rearward pressure. A BP that contains the pressure 100% in front of the BP snout in a 45 has an area of about 0.165 in^2 Here is where the barrel material and BP material become critical as the only thing that matters is the WEAKER material. If a thread will strip at around 12,000 psi then your maximum pressure in the barrel can not exceed 72,000 psi If you want to go to 75% then 54kpsi is your max load. What if your BP is not sealing then all bets are off as the next diameter is around 0.616 and the area there is about 0.3 which means the BP would need to contain 16kpsi at 54,000 and our BP's are most likely not designed for that load, as there just not enough thread engagement. edge.
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Post by Dave W on May 20, 2014 16:55:57 GMT -5
We all have custom barrels but not all have lugs on there bolts. If you trust the set screw holding the bolt on the 700ML for 78gr IMR4198 that's cool. It's not me pulling the trigger. The barrel is designed to contain the radial pressure and the BP to contain the rearward pressure. A BP that contains the pressure 100% in front of the BP snout in a 45 has an area of about 0.165 in^2 Here is where the barrel material and BP material become critical as the only thing that matters is the WEAKER material. If a thread will strip at around 12,000 psi then your maximum pressure in the barrel can not exceed 72,000 psi If you want to go to 75% then 54kpsi is your max load. What if your BP is not sealing then all bets are off as the next diameter is around 0.616 and the area there is about 0.3 which means the BP would need to contain 16kpsi at 54,000 and our BP's are most likely not designed for that load, as there just not enough thread engagement. edge. Thanks for that post, saved me the time of typing out a bolt thrust thread. Very timely.
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Post by 12ptdroptine on May 20, 2014 19:41:55 GMT -5
Man I am loving this. Learning a lot. So it would seem...IF I understand correctly...that I am on the upper limit of the safety margin? Thanks drop P:S: Please keep the replys coming
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Post by edge on May 20, 2014 20:11:08 GMT -5
My only point is we don't know Thread stripping is not as easy to calculate as bolt shear or tensile strength because the threads on both of our mating pieces are cut threads of unknown class and quality and unknown heat treat. The BP threads have only about 9/16 of an inch of thread engagement. To make matters worse not all threads carry the load at the same time, generally the first 3 threads carry almost all of the load so it will strip like picking up a slinky but that may or may not be an advantage for a BP since it may add time to the failure. Now I just put a number of 12kpsi and that may in fact be low, but that is about what centerfire locking lugs are designed to hold in case of a total case head failure...but just not on every shot edge.
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