Colombian Mauzer Caliber

[mgva]

I have purchased a Colombian Mauser dated 1957. I was told that it was a 30-06, however with 30-06 brass (no bullet) trimmed to 2.484 (Minimum length) the bolt will not close. Using a go gage in 30-06, the bolt will close with effort. What calibers could this thing be and how do I determine what it is?
Thanks
Dennis

[leadbutt]

Have you slugged the bore to see if its a 30 caliber? Are there any marks or stamps along the side of the barrel or reciever? THey all so used the 7x57 mauser

[mauser98us]

Does the rear of the receiver have a notch. When these were converted to 30 cal they were all notched so the longer ammo could be used on strippers. If not,I would venture it's a 7mm. Slug your bore.

[GatCat]

You might want to consider doing a cast of the chamber...it would be the most accurate way of telling exactly what it is.
Mark

[mgva]

Here is some more information. On top rear of the receiver is ".30" .Right front of receiver is "R. Famage" and "1957"

The only marks on the barrel is "+S" and an oval with a crown on top and the letters "IE" and "IG" inside. Not sure I read the letters right.

A 7mm (.284") drops right thru the barrel. a 30 Cal (.308) looks to fit about right.

Could this be a new barrel fitted, but not finished reamed? So that it was never properly headspaced.

Thanks
Dennis

[Mikey]

Well, you could have a short chamber since the 30-06 no go guage allows the bolt to close but with difficulty and this can be rectified easily by a gunsmith by cutting the chamber properly; but I would like to ask if you dropped the no go guage into the chamber and then tried closing the bolt or if you chambered the guage from the magazine?  Same question for the empty shell casing.  I doubt the barrel was set back and the chamber cut for 308 as it would not allow the bolt to close on the 06 no go guage if it had been. 

Make certain the chambver is nice and dry and you should be able to pull the bolt out and drop a dummy round right down into the chamber and hear it go 'clunk', sorta, maybe sort of 'snick', but drop right in.  You should then be able to take the rifle and either shake the round out of the chamber or fling it across the room - this indicates you probably have a properly cut chamber and how 'generous' it may be since it is mil-spec.

Is the serial number on the bolt matching the serial number on the rifle - if not it could be a poor fit and may need some gunsmithing.  Have you looked into the chamber to see if there is any roughness or burrs plainly evident or that something is plainly out of whack??  Let's keep trying, those are nice rifles.  HTH.

[mcwoodduck]

Well my guess are.
A) 7X57
B) 7.65X53 looks like a .32 caliber 308.
best bet is to take it to the gun smith and have the chamber cast.
Who knows what someone did to the gun before you got it?
Stuck a 308, 300 savage, 8X57 barrel on it.

[billy_56081]

Do a chamber cast. If it closes with effort on a go gage it MAY be a 30-06 with slighly short head space. A chamber cast is the first thing you need to do.

[torpedoman]

Did you remove the extractor before using the chamber gauge??

[billy_56081]

Did you remove the extractor before using the chamber gauge??

Great point Tman, military mausers do not jump the rim when loaded directly in the chamber. Load from the magazine to let the rim slip behind the extractor.

[mgva]

Thanks for all the information. I will cast the chamber and let you know the results.

Thanks
Dennis

[1911crazy]

This mauser came in 7mm mauser and in 30-06.  But some of the south american mausers were also in 7,65x53 too.  I know some of them switched from one caliber to another.  I would search for the columbia mauser to see if wikipedia comes up it may have the info your looking for.  I'll also look in my book of military mausers of the world too and get back to you.

My  quick search comes up with Columbia before ww1 purchased 1891 argentine mausers in 7,65x53 arg.  After ww1 they purchased mausers from Brno in 7mm mauser and later converted them to 30-06 as the info tells me.

Just search "columbia mauser"  lots of info / history comes up

[mgva]

You may have hit it on the head.

Here are the results of my chamber cast:
Diameter in front of the rim: cast=.471

[mgva]

I'll try again

Here are the results of my chamber cast:
Diameter in front of the rim: cast=.471    30-06=.470    7.65x53=.473

Diameter at the shoulder: cast=.447    30-06=.441    7.65x53=.429

Diameter at bullet end: cast=.347    30-06=.339    7.65x53=.346

Overall length: cast=2.433    30-06=2.494    7.65x53=2.110

It looks to me like it is part 30-06 and part 7.65x53mm. Can this be reamed to 30-06?
Thanks
Dennis

[billy_56081]

How about length? Bore diamiter?

[littlecanoe]

Have one of these.  Shot 30-06 fine, that is it chambered properly.  However, the barrel was very corroded.  I cleaned it and shot quite a few through it.  4 inch accuracy at 100 yds seemed to be the norm.  Great action.  Thinking about re-barrelling it to 25-06 down the road.  I'm thinking that they had over sized bores based on my experience. 

[mgva]

Barrel length is 22 1/2"  It is a stepped barrel.

Slugging the bore yields a bore diameter of .3085

Thanks
Dennis

[Larry Gibson]

mgva

Could this be a new barrel fitted, but not finished reamed? So that it was never properly headspaced.

That appears to be the case.  A good gunsmith can finish ream it or you can do it yourself with a rented reamer and extension, it's not difficult.

Larry Gibson

[dud]

i have 3 of these actions all are marked just like yours and are 3006.make sure the chamber is real clean.once you fire the brass will chamber quite easily.