The recent posts about Whitworth Express rifles have got me pondering. Assuming there is enough "meat" in the Whitworth 375H&H barrel to rebore to .411", would it be feasible to rechamber one to 400H&H? I just played with a couple of dummy 400H&H rounds in a 375H&H Whitworth. The 400 has a lot of taper and a long neck. Magazine feeding and loading shouldn't be much of an issue. I imagine the barrel would need to be set back but by how much? Any thoughts on feasibility?

I thought the 458 and 375 MKX were the same taper. However ammoquide raises several issue with case shape.

I have a Zastava and though about the same thing but decided against it. All factory Whitworth, Interarms Mark X, Charles Daly, Remington 798, Z98s in .375 H&H are opened up almost entirely to the front. I wasn't comfortable with this above the .375. I am not trying to start a flame. They have been made this way for years and all functioned and worn fine. I just didn't like the idea of stepping it up in these actions. If I was able to start with say a 7mm action and have a gunsmith open it up a little in both directions I would not have this reservations.

While I've had concerns with taking a MKX to something hotter than a 375 a 400H&H wouldn't raise that much of a concern with me.

I've thought about the same thing. Watch though if your 375 whitworth has a recoil lug on the barrel. My gunsmith thought it was set fairly deep, safe as it was, but a 411 rebore would leave pretty little meat in the barrel for the new bore. Also looked to me like the long neck of the 400 H&H would not allow a straight re-bore to create the 400 chamber without a pretty significant setback. Bob

quote:

Originally posted by bobc:
I've thought about the same thing. Watch though if your 375 whitworth has a recoil lug on the barrel. My gunsmith thought it was set fairly deep, safe as it was, but a 411 rebore would leave pretty little meat in the barrel for the new bore. Also looked to me like the long neck of the 400 H&H would not allow a straight re-bore to create the 400 chamber without a pretty significant setback. Bob

I was thinking that a rebore would leave the sights in place and wouldn't require stock work. I would have something to try the cartridge out in before ordering a rifle made in that caliber.

Do you think one or two turns setback would do it?

Bolt thrust is the issue and the 400 and 375 are nominally the same. Both have an MAP of around 62-63k. There is no increased risk just by caliber change. I re-barrleled a 375 MK X to 416 Remington and shot it for years without issue. Another poster has it today and may still be banging away with it. Before that it was a 300 Wby and before that a 375 Ackley Improved, all on the same action. Never had any bolt thrust issues, even as a 300 Wby.

As I was drinking my coffee this morning I drew up the 400 over the 375H&H because of the 400 shoulder position it will not clean up the shoulder of the 375. You are lookiing at .316"+ setback.

Thanks, that's what I thought. Awfully long neck on the 400.

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Originally posted by ramrod340:
You are lookiing at .316"+ setback.

Thanks. That kind of defeats the purpose of using the same barrel. I guess rebarreling would be the way to go. Maybe someone with a Mauser action will be interested in a nice .375H&H barrel with "Whitworth Rifle Company" and a castle printed on it.

The max difference between the two is .008" The 400 would chamber and fire you would just end up a with a bulge each time at the base of the neck.

Wish I had the room for the Whitworth.

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Originally posted by ramrod340:
... you would just end up a with a bulge each time at the base of the neck.

I don't like the idea of that.

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I don't like the idea of that

I don't either. But I have seen it done (not the 400H&H) with no major issue with much larger gaps than this. As I draw the case drawings and measure the gap it is .008 at the max. Remember copy paper is .0038-.004". I wonder how much you would see or feel it.

My $ I wouldn't bore a factory MKX barrel. For the few $$ more (if any) I would simply get a new barrel.

I believe if you send the barrel to Douglas they will duplicate the profile for you, saving you the trouble of re-inletting the stock. I have done that several times with pre-64 Model 70 barrels with no problem.