Wednesday, May 31, 2017

7.35mm Carcano

One of my coffee drinking buddies had been talking about his Dad's rifle for months.

He remembers, with great fondness, walking through the Upper Peninsula's cedar swamps hunting deer with this rifle.  He claims it is capable of rolling deer at a 1/4 mile and that it only weighed a freckle over six pounds.  He said it was one of his Dad's WWII "bring backs".

Unfortunately, the action locked up.  He asked me to look at it.


It is a 7.35mm Carcano.  In the 1930s the Italian Army determined that they needed a more powerful weapon than the 6.5mm Carcano.  They took the 6.5mm, slightly increased the case capacity and increased the diameter of the bullet from 6.5mm to 7.35mm which is 0.299 inches.

The onset of WWII hostilities found the Italians with one foot on the dock and the other in the canoe.  Most of their army was still outfitted with the 6.5mm rifles so they ceased production of the 7.35mm rifle and retooled for 6.5mm to meet the increased wartime needs.  The three years of 7.35mm rifles produced were squirreled away and issued to "secondary" defense personnel.

Other bullets of similar size were the 30-06 (.308"), the British .303, Russian 7.62X54Rmm and the Japanese 7.7mm ( all 0.311 inches).

The front action screw had been replaced with the wrong screw.  The previous owner must have lost the original and tried it replace it with an "English" SAE bolt.

It is a pretty gun.  The blueing is in good shape and the beechwood (or chestnut) stock was refinished.

The accuracy of Carcano's is often considered a joke.  In general, there are two major factors (and in the case of this particular specimen, three factors). 

There was a huge amount of variation in ammunition velocity and all of the ammo was pooled.  A sample of six cartridges might have 700fps difference between the slowest and the fastest.

The stock does not have a metal cross piece aft of the recoil lug.  Repeated firing has the potential to batter the stock and loosen up the connection between the action in the stock.

In the case of this rifle, the front screw is bottomed out in the hole and is loose.  I once had the honor of firing a muzzle loader with this condition and was not able to hit a paint can at twenty paces.

The locked up action

One consequence of firing over-pressure ammo is that the brass of the case flows.   The wall material moves aft and pinches shut (or narrows) the extractor groove of the case.  Lifting the bolt handle causes the extractor, a small steel claw, to slide radially in the cartridge's extractor groove.  Unless, of course, the groove is narrowed.  And then the bolt handle will not lift.

I don't know if the over-pressure ammo was WWII surplus that degraded over time?  Given the variation in new ammo it is possible that the ammo was over-pressure the day it was made.

Another possibility is that some Billy-Bob tried to reload the old ammo with .308 bullets.  Firing an oversized bullet down a smaller bore is guaranteed to spike pressures.

The maximum chamber pressure listed for the 7.35X51mm Carcano is 51,000 psi vs 62,000 psi for the .308 Winchester.  The 7.35mm Carcano also has about 10% less case capacity (volume) than the .303.

Given the fact that this is a pretty gun, the action is locked up, the front action screw goobered up the threads in the action, the rarity of the ammo, the complete lack of reliable reloading data and the dearth of 0.299" bullets...I am going to tell my buddy to hang it on the wall and to cherish his memories.

2 comments:

  1. Just a minor point... The SA in a square denotes Finnish ownership, making it a fairly rare and valuable (for a carcano anyway) version. Numrich as well as other suppliers should have the necessary parts.

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