In the course of research for my mad M95 project, I've seen much made of "chamber pressure" as being the limiting factor in whether a load is safe in a given action. It would seem to me that the force applied to the weak link in the action (lugs, I would assume) is the limiting factor, but pressure alone misses the effects of increased area on bolt thrust when the bolt face is opened for a bigger cartridge. Or is some other factor dependant only upon pressure what the smiths are paying attention to?
Not that I would attempt something so insane (my shoulders are gimped as it is), but I ran the numbers on 50 Alaskan in the Steyr M95 simply because the cartridge could physically fit on the bolt-face and magwell:
50 Alaskan
From Wiki (not the best source for load data )
Pressure: 40,000psi
Base Diameter: .553in (my assumption for thrust area on the bolt-face)
-Area: .240in^2
Calculated bolt thrust: 9605.5lb (ouch)
8x56R, the "original" chambering
Pressure: 51,500psi
Base Diameter: .494in
-Area: .192in^2
Calculated bolt thrust: 9868.9lb (ouch-ier)
8mm Mauser (Greeks/Yugos rechambered their M95s to this)
Pressure: 57,000psi
Base Diameter: .470in
-Area: .174in^2
Calculated bolt thrust: 9887.3lb (hope those lugs had a +20lb safety factor)
45-70(the round I plan to rechamber to)
Pressure: 43500psi(taken from limit for 450Marlin, since SAAMI wussed-out the 45-70)
Base Diameter: .505in
-Area: .200in^2
Calculated bolt thrust: 8711.2lb (yawn...yeah right)
Are my math/assumptions seriously off, or are all these loadings within/near the stresses of the factory-tested 8x56R? I understand this "analysis" neglects the duration of the peak-pressure spike. But still, the Alaskan load at 3346ft-lbf causes 260lbs less bolt-thrust than the 2504ft-lbf Mannlicher? What am I missing here?! All indications are that recoil (determined by bullet momentum rather than bolt thrust, I know) from the 50 would surely kill me, whereas the 8x56R will merely maim me
TCB
Not that I would attempt something so insane (my shoulders are gimped as it is), but I ran the numbers on 50 Alaskan in the Steyr M95 simply because the cartridge could physically fit on the bolt-face and magwell:
50 Alaskan
From Wiki (not the best source for load data )
Pressure: 40,000psi
Base Diameter: .553in (my assumption for thrust area on the bolt-face)
-Area: .240in^2
Calculated bolt thrust: 9605.5lb (ouch)
8x56R, the "original" chambering
Pressure: 51,500psi
Base Diameter: .494in
-Area: .192in^2
Calculated bolt thrust: 9868.9lb (ouch-ier)
8mm Mauser (Greeks/Yugos rechambered their M95s to this)
Pressure: 57,000psi
Base Diameter: .470in
-Area: .174in^2
Calculated bolt thrust: 9887.3lb (hope those lugs had a +20lb safety factor)
45-70(the round I plan to rechamber to)
Pressure: 43500psi(taken from limit for 450Marlin, since SAAMI wussed-out the 45-70)
Base Diameter: .505in
-Area: .200in^2
Calculated bolt thrust: 8711.2lb (yawn...yeah right)
Are my math/assumptions seriously off, or are all these loadings within/near the stresses of the factory-tested 8x56R? I understand this "analysis" neglects the duration of the peak-pressure spike. But still, the Alaskan load at 3346ft-lbf causes 260lbs less bolt-thrust than the 2504ft-lbf Mannlicher? What am I missing here?! All indications are that recoil (determined by bullet momentum rather than bolt thrust, I know) from the 50 would surely kill me, whereas the 8x56R will merely maim me
TCB