why if 375 HH is considered bad for a double do you see so many out there. It seems like at this point it might actually be one of the most prevalent double rifle calibers ever chambered. You see it from the top makers HH, Purdey, heym ect you see it in English guns, German, and Austrian . It spans from old guns all the way up to new guns in all categories from 11k chapuis to 250k best sidelock. Is the 375 hh rimless problem overblown? is the difference in pressure a real issue?
Or is it more of a " this could be and issue" therefore the internet has been deemed wrong?
I seem to recall the chapuis rep on here posting in the big iphisi thread that they have never had a 375hh returned for an issue.
While rimless, high pressure cartridges like the 375 H&H Magnum (rimless) are better suited for a bolt action, there are certainly plenty of double rifles chambered for it. The factors that make these not ideal include,
- Bolt Thrust - https://en.wikipedia.org/wiki/Bolt_thrust
- Simply Bolt Thrust is calculated by the cross sectional area of the largest point of the interior of the cartridge case, multiplied by the maximum (peak) chamber pressure of the cartridge.
- Peak Pressure:
- 375 H&H Rimless has a Maximum Pressure of 62,000 psi
- Rimless cartridges such as the 375 Rimless operate at around 40,000 psi
- Clearly at 50% more pressure each and every shot, rimless break action rifles will become loose much sooner than their rimless cousins. It’s that simple.
- Pawl extractors – The spring loaded mechanical tabs that extend into the rim of rimless cases to provide the means of extraction are named “pawls”.
- My Heym .458 Win (rimless) has two per extractor and at least once ripped the rim off a stuck case.
- I’ve owned Merkel and Chapuis doubles that functioned with one pawl per extractor. I never shot those rifles enough to wear out those mechanisms.
Bonus: Diggory Hadoke on 375 Rimless,
https://www.vintageguns.co.uk/magazine/the-375-flanged-double
How long will a high pressure, rimless double rifle last before it needs a repair? Let’s think about this.
- Good quality bolt action rifles which are properly cleaned can last 5,000 rounds before the throat of the rifling is worn out, contributing to loss of accuracy.
- In most cases, the actions will be almost as good as new! Just re-barrel, or set the barrel back by taking off in in at the breech and muzzle, and rechambering and re-threading. This would be fiscally impossible for a break action double rifle!
- Note: Magnum cartridges with excessive powder for the size of the bore such as the .220 Swift, .264 Win Mag and others can “shoot out” their barrels in 1,000 rounds!
- How many rounds do most shooter launch from their hunting rifles in a lifetime? Think about this.
- Heavy recoiling rifles from 375 H&H and up do not get shot 1,000 in several decades.
- Double rifles in 375 and larger probable get shot less than most bolt action rifles.
- If any double rifle is shot enough to loosen the action, the rifle can be repaired can be repaired by a competent gunsmith, if you can find one! The process is to,
- Remove the action hinge pin,
- Machine a slightly larger diameter pin and insert into the action,
- Mil the barrel hook to fit the new pin.
- There is a lot of smoke blackening and hand filling to properly fit a new hinge pin to the barrel hook.
- This is a common practice for 100+ year old vintage side by side shotguns.
If considering any rimless double, examine the action with a automotive feeler gage.
- If the action can close on a .002” gage on the top and side interfaces of the barrel and breech, it has some wear but is serviceable (according to JJ Perodeau).
- If an action cannot fully close on a .001” feeler gage, that rifle is barely broken in.
- Warning: Once any SxS action has side to side wear as identified by a feeler gage, it will loosen faster due to side to side "hammering" generated by each shot!
A good quality 375 H&H double rifle while not ideal should give a caretaker much enjoyment before it needs a visit to a competent gunsmith. Could tightening an action change the rifle's regulation? In theory, yes! How much would it affect regulation? Perhaps a little.
The bottom line is there are many serviceable rimless doubles on the market. Their price should reflect they are not chambered in the more ideal, low pressure cartridges. How much of a price differential should there be? That’s a good question but a high quality rifle such as a Heym or better should fetch a higher percentage of price than middle grades such as Merkel. I’ve owned both… Finally, I would not touch a low quality double in any rimless chambering!
Personally, I've owned six double rifles and am down to only two. I need to let one go to its next "caretaker". I love my Heym 88B in .458 Win but also have strong affinity for high quality bolt action magazine dangerous game rifles.
As always, my babbling above is worth as much as you paid for it...
