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Old 12-06-2009, 03:14 PM
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Default Martini Henry rifle thread

A friend of mine has a Henry Martini rifle and wants to rebarrel it. He need to cut threads on the new barrel to fit the action. From what he told me (I havent seen the action) it has a 14V thread. Does anyone know this thread? Is this a British thread (like the 55 degree Whitworth)? Where can I find information on it. Im not familiar with it ..thanks
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Old 12-06-2009, 05:05 PM
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Mike, this might be one of those times he will need to get the three wires and a mike and measure the thread and cut to fit.

I have a chart or book really that gives barrel threads. It is out in the shop so I can look tomorrow and see if that thread is listed.

Rereading your post I am positive that it would be a wintworth thread as those guns were produced by the British.

At one time I had one that had been rebarreded to a blown out 22 hornet.
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Old 12-06-2009, 05:11 PM
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Thanks Charlie. I dont have the action in front of me or I would do some measuring. Im doing some advance planning. Whatever you can find would be great..tomorrow is fine. thanks
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Old 12-07-2009, 07:46 AM
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Charlie I have determined that the thread is
a 55 degree British whitworth. I am no
clear on how to cut this thread on a lathe. I see
how a radiused threading tool with a 55
degree included angle would cut the valleys
but don't understand how the peaks are cut????

Any help here???
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Old 12-07-2009, 08:26 AM
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My understanding is:

You make the outside diameter to the internal outermost diameter of the threads in the receiver. Or to what OD measurements you get off the old barrel.

Then you figure out thread count, These would be the amount of threads cut per Inch. Then you figure out thread pitch and this has to include the depth of thread since you can have the valley/root of the threads to thick or thin.

Not sure if I explained it any better. I can see it in my mind but doesn't always make it to words.

I'm sure someone else with more experience will chime in,
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Old 12-07-2009, 08:34 AM
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Here is a picture of the British Whitworth thread form. I must be missing something simple. You can buy a 55 degree center gage, you can buy or make 55 degree radiused thread cutters but how do you machine the...ah it just hit me. DOH The radius cutter cuts both the peaks and valleys as it turns the thread. I dont know why I couldnt see that..senior moment I guess. I do know that the British Whitworth thread is stronger than a SAE thread of the same diameter because the radiused corners do not allow for a stress riser. I also know it created havoc during WWII in the manufacture of war materials here in the US for Britain.
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Last edited by tnmike; 12-07-2009 at 08:39 AM.
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Old 12-07-2009, 11:58 PM
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55* Whitworth thread is also used on the famous Mauser 98.
It is the norm to replace these barrels with one threaded 60* American Standard.
For example there are a couple dozen barrel makers from which you can order replacement Mauser barrels, with very few exceptions you will get a 60* thread unless you specially request 55* Whitworth.
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Old 12-08-2009, 12:04 AM
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Mike I am sorry I just totally forgot about checking the barrel thread chart and seeing if it is listed.
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Old 12-08-2009, 07:08 AM
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It is the norm to replace these barrels with one threaded 60* American Standard.



I will readily admit I am not an expert on the
british whitworth system but from everything I have
read I am surprised a 60 degree sae thead
will interchange. I am not doubting what you say
but I have read lots of horror stories on british car
and motorcycle forums.
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Last edited by tnmike; 12-08-2009 at 08:31 AM.
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Old 12-08-2009, 05:59 PM
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Mike,there were a couple of different sizes of actions. Hope this helps.
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