Looking for recommendations on bottom metal for a 375 H&H Interarms MK X Whitworth

Duane Weibe www.bottommetal.com

Use Duane's or Sunny Hill; both are excellent products that are delivered when they say they will be.

I don't think you can get aftermarket bottom metal for a Whitworth mauser. If I'm not mistaken the box on most .375 H&H size aftermarket bottom metal is opened in the back and the Whitworth action is opened in the front. They used a standard size box with a cut open front and a cheesy piece of sheet metal is tac-welded in place to serve as the front of the box.

I guess you could buy an aftermarket box and have it extended. It would probably be very expensive by the time it was finished though.

Terry

I have one like Terry is talking about. The front is cut out and a piece of sheet metal tac welded on.

But another thing you could do is buy an aftermarket bottom metal but don't cut out the front. Instead weld a thick piece of steel to the front and then mill it out to the length you need. That way you won't have a piece of sheet metal on the front.

Check with Blackburn. He has the talent to probably make what you want without alteration.
Might cost a bit more but you would be getting what you want.

quote:

Originally posted by Abob:
Looking for recommendations on bottom metal for a 375 H&H Interarms MK X Whitworth

Unless something changed that I don't know about, the Mark X is a system (and pattern) 98. If that is true, we have them in stock ready for delivery...please call me if you want to compare notes Duane

quote:

Originally posted by Duane Wiebe:

quote:

Originally posted by Abob:
Looking for recommendations on bottom metal for a 375 H&H Interarms MK X Whitworth

Unless something changed that I don't know about, the Mark X is a system (and pattern) 98. If that is true, we have them in stock ready for delivery...please call me if you want to compare notes Duane

No, Terry is right, the Mark X and the FN .375's were simply opened to teh front. The front cut off the box and an extension tack welded n place. Are yours constructed in such a way, or more precisely, are you H&H mags simply extended to the front?

No...these are an entirely new cnc machined part, I'll post photos as soon as I can get some help to do so.

quote:

Originally posted by rem721:


No, Terry is right, the Mark X and the FN .375's were simply opened to teh front. The front cut off the box and an extension tack welded n place. Are yours constructed in such a way, or more precisely, are you H&H mags simply extended to the front?

I don't believe that is entirely correct. I have a FN(Sako) in 375H&H. It does have the sheet-metal extension in the front of the box, but it also has the rear of the box milled to provide extra length.

It has nothing to do with anything said on this thread, but a myth was promoted on this site by one of our "Gurus" who claimed to, "open Mausers to the rear only, when converting for long magnums" using a Blackburn box.

It is a fallacy that the Blackburn boxes are only opened to the rear. I have both Blackburn and PME long magnum boxes and both are opened up both towards the front and the rear compared to an FN standard (30/06 length) box. I don't have the measurements in front of me, but if memory serves the Blackburn box is opened twice as much to the front(.125") as to the rear(.60").

I've tried a Blackburn box on a Whitworth 375H&H and it did not fit the action nor did it fit the inletting on the stock. That's why I wrote what I did. I don't claim to be an expert or a "guru".

I don't have any idea about a FN action but the poster didn't ask anything about one.

This was the rifle I owned at one time and thought different bottom metal would be a nice upgrade and might make it a smooth feeder. It didn't work. If Duane has something that'll work that's great.


Terry

Also, I have not seen Duane Wiebe's bottom metal yet.

I asked D'arcy Echols if he had any experience with Mr. Wiebe's bottom metal. He replied that they will be, "well made if Duane as anything to do with them ." High praise IMHO....

quote:

Originally posted by TC1:
I've tried a Blackburn box on a Whitworth 375H&H and it did not fit the action nor did it fit the inletting on the stock. That's why I wrote what I did. I don't claim to be an expert or a "guru".


Terry

I agree 100%, the Blackburn box would be too wide and too far back to fit a Mark X. I did not mean to muddy the water.

And, I do consider you an expert BTW and I always pay attention to your posts and those by Rem721 as you both know your stuff.

The "Guru" I was referring to no longer posts on this site.

quote:

Originally posted by JBrown:

quote:

Originally posted by rem721:


No, Terry is right, the Mark X and the FN .375's were simply opened to teh front. The front cut off the box and an extension tack welded n place. Are yours constructed in such a way, or more precisely, are you H&H mags simply extended to the front?

I don't believe that is entirely correct. I have a FN(Sako) in 375H&H. It does have the sheet-metal extension in the front of the box, but it also has the rear of the box milled to provide extra length.

It has nothing to do with anything said on this thread, but a myth was promoted on this site by one of our "Gurus" who claimed to, "open Mausers to the rear only, when converting for long magnums" using a Blackburn box.

It is a fallacy that the Blackburn boxes are only opened to the rear. I have both Blackburn and PME long magnum boxes and both are opened up both towards the front and the rear compared to an FN standard (30/06 length) box. I don't have the measurements in front of me, but if memory serves the Blackburn box is opened twice as much to the front(.125") as to the rear(.60").

I don't recall anyone who has posted here saying that the Blackburn box was only opened to the rear. They go both ways, some to the rear and some to the front. Of course that doesn't mean someone didn't say it just that I didn't see it.

You cannot lengthen the mag by going solely to the rear otherwise you will have no bolt guide left to support the bolt when it is fully retracted. By guide I mean bolt bore, not the guide rib.

Even opening a Mauser to the rear .060 is a stretch...doesn't leave much of a bolt stop. James Wisner ued to make a new bolt stop housing that may have given that...maybe still does...Jim.....???


Never saw a Blackburn unit that allowed more than .015 or so. We've found this is the approx limit without serious modification.

This "opening to rear" vs "opening to front" has been discussed a number of times that I know of on these forums...sill haven't come up with the magic formula, but opening to the front (within reason) has been done for about a 100 years.

There's always some antecdote of this or that failure, but damned if I personally ever saw one in 40 years at the bench

So it would appear that the final answer to the question is to send the action to Mr. Wiebe, Mr. Blackburn, or whomever else makes bottom metal and ask that a custom unit be made to fit the action.

quote:

Originally posted by 22WRF:
So it would appear that the final answer to the question is to send the action to Mr. Wiebe, Mr. Blackburn, or whomever else makes bottom metal and ask that a custom unit be made to fit the action.

No! It doesn't need any custom bleeping bottom metal! He can choose off the shelf replacement bottom metal. the rails will have to be tuned to the bottom metal mfg he chooses. All replacement off the shelf bottom metal magazines are going to be within a few thou of each other...they will all crowd the rear wall as far back as practical..I say it again, this action opening procedure has been done about 100 years...this is not rocket science

Duane, I assumed Abob was looking for a "drop in" part that would fit his rifle and stock without a major modification. Probably a mistake on my part.

Terry

I have just personally examined an older Browning Mauser all-steel magazine assembly from a 375 H&H, it has been opened to both the front AND the rear just as Mr Brown has described. Obviously factory work, and very neatly done.

Speaking personally, I would not want a standard-length Mauser opened up to H&H-length only to the front, IMO it leaves far too little bolt lug area. I have relieved Mauser bolt stops as much as 0.100" to permit bolt withdrawal farther to the rear, with no problems. JMOFWIW.
Regards, Joe

J>DSteele: Tha leaves the bolt stop only about .100 thick???

quote:

I have just personally examined an older Browning Mauser all-steel magazine assembly from a 375 H&H, it has been opened to both the front AND the rear just

I have never seen a Browning 375. I do have a MKX Whitworth in 375. The vast majority of the opening is in the front. The rear has been opened only on the inside of the magazine box.
I thought I had run this issue before. This was my answer and measurments from back in 06.

Posted 06 September 2006 17:18
Well keep in mind these were all measure before coffee. First up my Whitworth is only .932 on the inside to get .985 I would have to remove one full side.

Anyway here is what I measured this morning. I tried to measure each at the same point. In the front due to the rounded corner this was a little difficult. These are all inside top and thickness for the rear tang(rear wall of magazine). Sorry how this looks but I don't know how to make it spread.
Action Rear Frt Length Tang
MKX Mag .918 .712 3.407 .115
MKX 06 .918 .713 3.407 .114
Daly Mag .917 .713 3.407 .115
FN Mag .907 .707 3.312 .116
M98 1909 .889 .705 3.303 .119
Whitworth .932 xxxx 3.68 .057
(375)
Laying the Whitworth mag next to the normal short mag MKX you can see in the rear metal has been removed. Since the front has the sheet metal extension spot welded on the inside I didn't think a front measurement would be of any use. I bought the FN Mag so I'm unsure if it was factory or altered by the smith that built the rifle.

So my take on it is comparing the MKX 06, MKX mag and Daly Mag the measurements are the same. But they are larger than the FN style and my 1909. The Whitworth 375 has been opened as much as possible without actually moving the rear magazine walls.

quote:

Originally posted by TC1:
Duane, I assumed Abob was looking for a "drop in" part that would fit his rifle and stock without a major modification. Probably a mistake on my part.

Terry

You are correct Terry

quote:

Originally posted by Duane Wiebe:
J>DSteele: Tha leaves the bolt stop only about .100 thick???

I just went out and measured the last one I did, on a 6.5-257 Roberts, and it's ~0.133-0.135". Have found that the bolt lug will imprint slightly over time but have been doing this for years on non-DGRs with no trouble. I expect that I could probably eventually cause major problems by slamming the bolt back repeatedly at full strength, much more than I have done so far, but I'm 6'-5" and 300 lbs so the bolt stops I've thinned have already gotten somewhat of a workout with no damage so far. So far.
Regards, Joe

SunnyHill has bottom metal in stock for the Whitworth in 375 H&H.

I know because I purchased one from Brownell's, thinking it could be modified for my 500 Jeffery (done on a Whitworth that was originally a 300 Weatherby).

Ended up exchanging it for another SunnyHill unit with a wider magazine box.

Very nicely made. I can vouch that it fits correctly.

Garrett

quote:

Originally posted by Duane Wiebe:
Even opening a Mauser to the rear .060 is a stretch...doesn't leave much of a bolt stop. James Wisner ued to make a new bolt stop housing that may have given that...maybe still does...Jim.....???


Never saw a Blackburn unit that allowed more than .015 or so. We've found this is the approx limit without serious modification.

This "opening to rear" vs "opening to front" has been discussed a number of times that I know of on these forums...sill haven't come up with the magic formula, but opening to the front (within reason) has been done for about a 100 years.

There's always some antecdote of this or that failure, but damned if I personally ever saw one in 40 years at the bench

Duane
I am not sure if I understand your .015" measurement.....

I think part of the disagreement about how much they(blackburn or wisner) are opened to the rear has to do with what we are using as a starting point.

I have always compared them to an FN 06 length box. I compared an FN action(06 length) to an unaltered VZ-24 today. I was very surprised to find that the rear of the VZ-24 mag well sits further(.030") back than the rear of the FN mag well.

According to my measurements the rear or the Blackburn box is .030" further back than the rear of the VZ-24 box. The Blackburn box is .060" further back than the FN 06 length box.

Also the blackburn box has a thinner rear wall than either the VZ or FN boxes, so the cartridges sit even further back in relation to the receiver.

I can post some photos that explain the measurements that I am referring to as soon as I get a chance.

As several folks have alluded, it's necessary to widen the box as well as lengthen it. Esp. for the fatter ctgs like the 458 Win Mag or Lott, 470 Capstick, and any of the sharp-shouldered necked cases like the 375 Ruger and 416 Ruger. This is key to getting the ctgs to sit down in the box, as well as to feed properly.

I have seen boxes heated and bowed (stretched) in front, front wall amputated and the stock itself used as the front of the box, and the sheet metal extender tacked on.

I played around with this quite a bit, considered amputating the front wall, shaving the back wall etc. In the end, I decided it was best to amputate the entire box leaving only a shallow rim at the bottom metal. And then I fabricated new boxes that were both wider and longer and were clamped between the action and the stub of the original box on the bottom metal. I sized the box to fit the well of a Hogue Overmolded stock perfectly (it has a full length Aluminum bedding rail). So there is no welding or inletting required. The resulting width will allow 3x470 Capsticks to lay down in a standard depth magazine. We do reinforce the front of the new box (where the seam is) with a gusset and that can be tacked or silver soldered onto the outer wall. This withstands the bullet noses hammering against the front wall, prudent for a heavy caliber.

We offered these rifles as kits in various DG calibers, they are almost gone and we are out of actions. We have some hinged bottom metal (Parker Hale pattern) left over which can be used as is for standard length ctgs, widened for the Rugers, or amputated and replaced for the cigar ctgs. The walls of the replacement box are such that you gain some length at the back and probably need to modify your bolt stop to pick up the ctgs. Most of the gain is at the front, requiring the feed ramp to be cut back.

Of course, with the wider box, you have to widen and bevel the corresponding opening in the action to some degree as well.

Bottom line is we found this solution to be very inexpensive and quite effective. You don't need new bottom metal at all, if you already have a PH style or even a mil 98 action. You just need a new box, a hacksaw, a file, and a steady hand. If you are going to use a stock other than a Hogue OM, you will probably need to inlet the new box as well, but you don't need to touch the bottom metal inletting.