Originally Posted by Gatofeo
Ken Waters, in his 1970s groundbreaking article that created the three action strengths for the .45-70, rated the H&R Safari break-open .45-70 as equal to the new 1873 Springfield "trapdoor" .45-70.
This is the "Group 1 - Weak Rifles" category.
That said, you can probably safely use loads intended for the 1873 Springfield, but no hotter.
That was then and the H&R has been upgraded over the past 30 years. Nowadays we routinely load H&R Handi rifles to Marlin Lever level loads. It's easily capable of handling Buffalo Bore 500 grain .45-70 ammo
, which says this at their website:
Its use should be limited to the following firearms:
All Marlin 1895 (1895 Marlins are all model 336 actions, chambered in 45-70) iterations made since 1972, all Browning 1885 and 1886 copies, New England Arms Handi Rifle, T/C Encore, ALL falling block actions made of modern steel such as Ruger #1 and #3, Shiloh, Christian and Persoli Sharps, all Winchester 1886 iterations made since 1915 and all Siamese Mauser bolt actions.
Never use this ammo in ANY original or reproduced "Trap Door" action as the design is far too weak.
With all respect to Ken Waters, we've found that the current Handi rifles are capable of handling pressures far above the old Trapdoor loads.