I've been trying to find info on what the Hepburn action's are rated to pressure wise. See a lot written they're one of the stronger actions, but can't find a PSI/CUP number associated with them. Anyone have any info on what they're rated at?
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I've been trying to find info on what the Hepburn action's are rated to pressure wise. See a lot written they're one of the stronger actions, but can't find a PSI/CUP number associated with them. Anyone have any info on what they're rated at?
Nobody has ever "rated" any of the old actions. People have built some pretty warm varminters on Hepburns though, but usually for cartridges with a base diameter of the .219 Zipper or less. They seem to survive this.
Two things matter: Hoop strength around the chamber, which is as much the barrel as it is the action. The other is bolt thrust, (pressure x area).
So the while the old Hepburn might be happy at 50,000 psi in the .22-3000 Lovell, it might just as well be unhappy at 42,000 in 7x57.
I doubt that any responsible 'smith would recommend building anything in the .308 family on one.
At this point they're much too valuable to risk them by pushing them to extremes.
The weak point of the Hepburn is the rebounding hammer which pops it back to half cock after the gun is fired. With no hammer pressure on the firing pin, high pressures will extrude the fired primer back into the firing pin hole, making the action hard to open unless cocked and snapped again.
Some Hepburns were converted into high intensity varmint rifles by bushing the block for a smaller firing pin and grinding the mainspring to eliminate the rebound feature. With the hammer down, and a smaller pin hole, the extrusion tendency was eliminated.
Then, of course, the gun had to be half-cocked by hand, eliminating a lot of the convenience of using the thing.
I would say the block and mortise could withstand most medium-and high-intensity cartridges, but there are better actions to use them in. Modern cartridges generally mean telescopic sights, which means that the Hepburn’s excessive drop will need an extremely high comb on the stock to compensate. I’ve never regarded any of the modernizations I’ve seen in pictures or firsthand as triumphs of artistic beauty. And I think the original Hepburn’s are quite handsome rifles.
Years ago, I had a Remington Hepburn in either .219 Improved Zipper or a similar variation, .22/.30-30 Ackley Improved. Never figured out which it was but had the barrel rechambered to the standard .219 Zipper as I had other rifles in that chambering. No problems with either cartridge but I didn't use maximum loads as I remember. I'd prefer a modern action if I was going to load warm.
I believe with high intensity rounds in the hepburn that the extraction may become a problem with upper end loads. A lot of the old single shots had weaker extraction than the modern actions.
Not much made in a rimmed cartridge that is going to be an issue in a Hepburn. Very hot "Improved" cartridges might be an issue if pushed to max levels. Mine are all in old hyphenated cartridges, but I never considered chambering or rebarreling a Hepburn in any high pressure cartridges.
A properly done Mann-Niedner firing pin mod would adequately deal with the rebounding-hammer weakness, would it not? Assuming that the body of the pin were large enough.
The rebounding hammer never bothered me, but then I've never owned a Hepburn that wasn't in a traditional chambering. And only one of mine is a single trigger.
Reason for the original question was I had gotten one and it had been rebarreled to 25-20 WCF. It ended up having a crack in the receiver right in the corner near the front of the breechblock. Didn't figure the 25-20 would have been enough to do this but would have figured whoever rebarreled it would have noticed if it was cracked prior to the barrel work. Or perhaps it cracked from the rebarrel. Was small and hard to notice but definitely cracked.
My bet is it was rebarreled previously and whatever that was caused the crack. So thye decided to rebarrel it again to a lighter caliber that wouldn't affect being shot with the tiny crack.Quote:
Originally Posted by hawkenhunter50
I'd simply send the receiver to Restorative Firearms Welding, and have him fix the cracks. Once he's done it will be as strong as new again.
http://www.restorativewelding.com/re...g/Welcome.html