Keyholing and stiff bolt lift

My son has a new toy, 1900 Spanish Mauser rebarrelled by their military to 7.62-51 in 1950.
Bore and crown look ok. So he bought some Greek surplus ammo for it and off we went to the range yesterday
First 3 shots went ok, but the bolt got progressively harder to lift. Last 2 the projectiles went sideways and really
Hard to eject. Ejection marks on cases. Too hot obviously
My question is - Why did it get progressively worse ?
Why didn’t the first projectiles tumble ?
I’ve loaded up some nice soft loads with Sierra 150 gr spitzers to try next range day.

Quote:

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Originally Posted by Frogfeatures

My son has a new toy, 1900 Spanish Mauser rebarrelled by their military to 7.62-51 in 1950.
Bore and crown look ok. So he bought some Greek surplus ammo for it and off we went to the range yesterday
First 3 shots went ok, but the bolt got progressively harder to lift. Last 2 the projectiles went sideways and really
Hard to eject. Ejection marks on cases. Too hot obviously
My question is - Why did it get progressively worse ?
Why didn’t the first projectiles tumble ?
I’ve loaded up some nice soft loads with Sierra 150 gr spitzers to try next range day.

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Greetings @Frogfeatures,
The problem was most likely the crap ammo. My experience with the Greek .303 ammo is that some is excellent and some absolute rubbish. Likely due to poor storage.
Regards Grandpamac.

I am guessing a bit here so sorry this isn't a definitive answer.

I have heard of the old spanish mausers needing to be babied a bit. The ammo sounds like it's at fault here though so your plan to try some hand loads is a good move. I'd bet with a starting load of 2206H or 2208 that you won't get the progessively heavier bolt vs 70yr old surplus that could be degrading, spiky, or generally too hot for the gun. I'd give the bore a good deep clean before you head back out, focussing on the chamber area in case there's a carbon ring building up. Make sure it's dry as a bone in there.

What was the weight of the projectiles in the surplus and what's the twist of the barrel? That or a shot out bore is all that really explains tumbling. If it's borderline then it might not be noticeable on every shot. Might need to go to 130gr or flat base if the gamekings don't work out.

Hi
Were these originally 30-06 and then fitted with steel plug chamber adapter to make them 762?

The Sierras are flat base, so that should help
Gave the bore and chamber a good clean.
It’s a carbine, so short barrel.
I just don’t get why it got progressively worse ?

Edit the Greek stuff was 147 gr.

Bore was originally 7 x 57

If you have any of the Greek ammo left I would pull the projectiles, dump the powder, ad reload with a mild AR2206H load. If they shoot well it was degraded powder. If the cases are hard to extract you probably have a mildly corrosion in the chamber - don't panic a gunsmith could polish that out OK. If they still keyhole its the projectiles or the barrel.

My bet is the powder has degraded. I have a friend who's WWII 303 ammo was going off like a 300 Win Mag. We pulled the bullets, and when lit outside it virtually exploded. Cordite definitely degrades over time and moves closer to detonation than a controlled burn, who knows what propellant is in the Greek 7.62 military ammo. There's a reason why armies surplus their old ammo......

Some of the GC greek 303 ammo I tried ages ago was a bit naff.
First shot seemed quite soft with the next few recoiling harder than the last.
Group was uninspiring.
This was in a bsa sporterised P14 with a big scope.
Not light but no recoil pad either.
Had been many years since I shot a 303 so not sure if the first shot was weak or the last couple were cranky
Not a lot of shots fired though
Not even 20. Very small test sample but sounds like pretty normal
As an added comment, got a friend who got 100 rounds of this in 308 coz it was the cheapest.
Had a couple of misfires at some goats on a trip up to kaikoura we did several months back
When it shoots it is acceptably accurate but I wouldntbtrust it

Check if it is a small ring mauser or M 98. Some of the older Mausers were converted to caliber's theyr metallurgy wasn't capable of

You are shooting a 7x57 converted in the 1950s.

An early 50's convert will more likely be to 7.62×51mm CETME

Note the CETME, not NATO. CETME is less powerful. The original projectiles were plastic cored thin jacketed lead rounds (crazy having plastic core!)

Spain didn't use 7.62x51 Spanish-NATO until later and then only 7.62x51 NATO from 1988.
This forced Spain to internally rework their firearms to accept the more powerful round.

Do as 243wssm mentions, load up some reduced power 2206h load with lighter 130gn projectiles and see how it goes.

Greetings All,
I have used a 150 grain round nose with 38 to 40 grains of AR2206H in my .308 rifles for a light target load. The lower load chronographed 2,350 fps in a 22 inch barrel. Shot well.
Regards Grandpamac.

In fact CETME Mil projectiles due to the plastic core would only weigh 113gns. But long and skinny.

Hornady and Sierra do cheap 110gn and 125gn projectiles.

Barnes will be too $$

Quote:

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Originally Posted by grandpamac

Greetings @Frogfeatures,
The problem was most likely the crap ammo. My experience with the Greek .303 ammo is that some is excellent and some absolute rubbish. Likely due to poor storage.
Regards Grandpamac.

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Yep, never judge a milsurp on how it does with questionable ammo. New quality .308 is not that expensive.

Loaded up 43 gr 2206h to try next range day. ( Sierra 150 gr )
Thats ADI’s start load.
We’ll see how that goes.
I pulled 5 rounds of the greek stuff, cleaned the cases and I’ll try
some 150 gr Hornady projectiles as well.

PS thought I’d see how the military powder burned, went off like a flame thrower.
It was very fine granules.
I used a kinetic hammer to pull them down, surprised at how easily the projectiles came out.

Could the progression be as a result of the chamber heating up, and therefore increasingly heated old and possibly degraded gunpowder in the chambered cartridges? I can't think of any other variable that would cause progressively worse performance.

Greetings All,
I would not read too much into the varying pressure due to the nature of the ammunition being used. I have read that some of the Greek ammo was tumbled to clean it up. This is a doubtful practise due to the chance of the deterrent powder coating being rubbed of in the process. Different batches receiving different treatment and then combined before packing could easily account for quite different pressure in different cartridges. I think the message should be clear that don't use ammo of doubtful history and if you do don't expect too much in the way of consistency. Drawing conclusions on the basis of crap ammo is futile at best.
To @Frogfeatures AR2206H is a powder that you can go well below start loads with safety. Hodgdon gives a minimum of 60% of max loads for reduced loads with H4895 (AR2206H) and I have gone as low as 32 grains with the 150 grain plated projectiles with good results. Much below that the cases were smoked full length.
Regards Grandpamac.

@hamsav hi just my too cents worth i have a 303 1917 smle did the same thing re ripping the patch i got a patch and put some autosol polish from repco on the patch and worked the bore made a big difference as i shoot cast only in cheers

Quote:

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Originally Posted by Frogfeatures

My son has a new toy, 1900 Spanish Mauser rebarrelled by their military to 7.62-51 in 1950.
Bore and crown look ok. So he bought some Greek surplus ammo for it and off we went to the range yesterday
First 3 shots went ok, but the bolt got progressively harder to lift. Last 2 the projectiles went sideways and really
Hard to eject. Ejection marks on cases. Too hot obviously
My question is - Why did it get progressively worse ?
Why didn’t the first projectiles tumble ?
I’ve loaded up some nice soft loads with Sierra 150 gr spitzers to try next range day.

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Where you do get the 1950 from? The 7.62x51NATO was only developed in the 1950s so 1950 seems early, the .308Win was 1952 and the NATO cartridge only two years later.

The 7x57 Mauser has comparable pressure to the 7.62x51NATO so the CETME thing is a non-issue. The action will handle it especially as CIP proof loads for 7x57 will wayyy exceed the 7.62x51NATO's rated max pressures.

I think the barrel has 1953 stamped on it, from memory.
Pretty sure the problem was the milsurp ammo
I’ve loaded up 2 different rounds to try, one at ADI’s start load, and one a little below that.
He’s only shooting paper, so a nice soft load will work fine.