interarms mark X


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dpostel83
May 15, 2009, 12:34 AM
ok guys, i hope someone can help. i have an interarms mark x of unknown caliber. myself and 2 other guys i know have searched and search for some sort of markings on it to identify caliber. all that is on it other than manufacturer info is the serial number: A303497. is there a way to findout with just the serial number. my local gunsmith will be out of the shop for another 2 weeks, so i cant have him look at it.

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kcmarine
May 15, 2009, 12:50 AM
Not sure... measure the muzzle with a measuring tape or calipers... take a picture and show us... that way, you'll at least know the bore diameter.

jmr40
May 15, 2009, 06:48 AM
The Mark X is a popular rifle for a custom gun and it may have been rebarreled to another chambering after it left the factory so I would not trust the SN.

The chambering is almost always on the barrel and could be on the part of the barrel in the stock. This could happen if it has been rebarreled. Have you taken the action out of the stock?

jbaker
May 15, 2009, 07:06 AM
You could take the stock off and see if the bottom of the barrel was marked with who installed the barrel or take it to a gunsmith and let them cerrosfe the chamber.

SaxonPig
May 15, 2009, 08:44 AM
The barrel should be marked. If not, a smith can make a chamber cast to determine caliber. I would not guess.

MMCSRET
May 15, 2009, 08:58 AM
As said before the action is no indication of caliber. The bolt face might tell you if its for a belted magnum. I have a new, in the box, Mark X standard face action in my safe, I've had it for 10 years and just haven't decided on a barrel, the inspection papers with it are dated 1989, lots of Mark X actions sold for custom rifles.

TexasRifleman
May 15, 2009, 09:04 AM
I have a rifle built on one of these receivers. Many of them were sold as receivers only, for custom builds.

My barrel was sold the same way, an un-reamed .24 caliber blank.

It's chambered in a wildcat cartridge, the 6mm-06.

Having a gunsmith do a casting of the chamber is the only safe method to determine the chambering.

I absolutely would NOT fire it just because a round happened to fit.

rcmodel
May 15, 2009, 01:25 PM
+1000 TexasRifleman!

I built mine as a 25-06.

Sold as actions only in the 70's - 80's, and could have been barreled to any commercial or wildcat caliber based on the 30-06 size case.

A Cerrosafe chamber cast is the only way to find out what it is at this point.

rc

SuperMidget
May 15, 2009, 01:40 PM
Completely non-authoritative answer, but you can get a very close approximation by making several measurements.

First, measure the bolt face. 0.475" will give you a .308/Mauser/'06 based cartridge. 0.535" is belted magnum.

Second, measure length of the mag box. 2.8 is .308 based cartridge, 3.1 is x57mm Mauser based, 3.4 is '06 based.

Third, measure the width of the mag box at 0.05" in front of the rear, and just behind the shoulder stop. This one will be tricky because you will need to do some math on the proper dimensioning of a mauser magazine (formulas can be found over on AccurateReloading by searching that exact term). If it was a custom, and properly done the smith should have modified this at least in the shoulder area for better feeding of minimally tapered cartridges, but this is rarely done unless the smith was a perfectionist. If it has been altered, you can get a rough idea of shoulder dimensions in case the cartridge was Ackley'd or a shortfat or rebated rim cartridge was used.

Fourth would be to measure the bore diameter on the grooves. This part is important as all Imperial cartridges are groove to groove diameter.


Again, this is by no means 100% certain, only a cerrocast can be. But it can put you in the proper ballpark to give your smith a heads up on. Also a great way to waste an afternoon. =)

rcmodel
May 15, 2009, 01:55 PM
I hate to bust your bubble, but all standard length Mark-X 98's used the exact same magazine box.
The belted mag action used a different one.

Standard 30-06 length = 3.385" long.
Short .308, 22-250, etc = 3.385" long, with an internal block.
Belted Mag = 3.600" long.

All measureing the grooves will tell you is what caliber the bore is, not what cartrige of that caliber it is chambered for.

As already stated, the only way to find out what this unmarked one is chambered for is with a Cerrosafe chamber cast.

rc

dpostel83
May 15, 2009, 02:29 PM
i guess i'll have to wait until by gunsmith gets back to work and have him cast it

SuperMidget
May 15, 2009, 05:26 PM
I hate to bust your bubble, but all standard length Mark-X 98's used the exact same magazine box.
The belted mag action used a different one.

Standard 30-06 length = 3.385" long.
Short .308, 22-250, etc = 3.385" long, with an internal block.
Belted Mag = 3.600" long.

All measureing the grooves will tell you is what caliber the bore is, not what cartrige of that caliber it is chambered for.

As already stated, the only way to find out what this unmarked one is chambered for is with a Cerrosafe chamber cast.

rc

Mark X's that were made during the same time the yugo plant was making them for Whitworth had the FN pattern magazine box which did call for correct width magazine boxes and different magazine followers. They may have changed this at some point, I don't know, but the early spec' was based on FN contract machines and FN contract plans.

So far as I know, the only Mark X that uses a 3.6" length box was the .375 H&H. I thought they limited that to only that cartridge because you have to hog out a decent chunk of the action front and rear.

From the very limited sampling of two early '70s rifles that I have had in my hands, I can tell you that the .30-06 and the .270 WCF had different shoulder dimensions in the magazine box. I haven't taken apart any of the push button Charles Daly's or Mark X's to see if this holds true.

It may be that we're discussing mangoes to persimmon simply due to the age of the platform and the ownership/distributor changes over the course of nearly 50 years.

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