RememberTheSomme
CGN Ultra frequent flyer
- Location
- Nova Scotia
The premature throat erosion may be from the powder type and charge itself coupled with slightly undersize projectiles in some measured lots.. Exactly how the Chinese arrive at standard 556 M193 and 762NATO velocities is anyone's guess. Two identical looking rounds fired in the same rifle can produce the same muzzle velocity except they both accelerated the projectile in totally different heat and pressure curves inside the barrel, especially in the lead or the first 2 to 4 inches of rifling. An undersize projectile unable to fully seal a leade with the chamber pressures approaching 60,000psi, would exhibit huge fireballs at the muzzle that actual lead the projectile and envelop it at exit.
I noticed two weeks ago, the powder in a round that had been driven back into the case while chambering in an Armalite M15A4, possibly from undersize or lack of proper crimp or both, and the dumped powder appeared to be of a "blended" type, with different grain sizes and different types mixed in. In particular flattened ball and spheroidal ball grains in the same charge.
I witnessed the first keyhole as well at 50 yards from my son's new 1/9" twist Armalite with less than 250 rounds fired total and while using 223Nork. We had maybe 400 rounds of it up to this point no problems. The bullet had yawed a full 90 degrees and struck completely sideways while passing through a single target sheet paper. I measured all rounds left in the CJ 95 lot#26 we have on hand and did not find any under .224". The one that keyholed, had it been driven back into the case, and deformed like the one we found, and had to jump long into the leade while off center and deformed would have made a nasty barrel whip on acceleration and most likely would be un-stabilizable, hence the keyhole. Just speculation for others versed in internal/external ballistics to ponder and rebutt.
With the unknown powder type and reports of undersized bullets(.220" vs .224"), I'm going to hold off on buying anymore of this ammo in the short term. I have put over 800 rounds of Nork 762NATO through my M-14 with no issues noticed yet.
Again as I've stated many times in other threads on Chinese ammo,... what the pressure curve is and flame temp in the throat and how the velocities are obtained in regards to weight of charge and burn rates as compared to NATO spec ammo is anyone's guess.
This in itself is not a bad thing altogether, as many different world wide ammo makers use a variety of their proprietary powders or others, to obtain spec velocities for a given cartridge. Some ammo 's are harder on certain gas guns actions or barrels than others, this is a fact. Look at MkVII .303 Ammo loaded with Cordite versus more modern day nitro cellulose for instance. Same velocities at the business ends, but Cordite being far harder on throat erosion.
The trade off I guess is in absolute economics. If an AR barrel is worn beyond acceptable accuracy after say 5000 rounds of Nork that cost 1200 dollars as compared to 8,000-10,000 rounds while using AE for a cost of 3200-4000 dollars, and if the gun's functionality properly and accuracy was acceptable, would'nt a new 300 dollar barrel still be the cheapest option? Finding and having a new barrel installed on a Swiss Rifle as in Steve's case would be far more costly, thus you need to weigh this all out, if indeed the Nork ammo is proven to be anymore abrasive on throats than any other bulk .223/556 we have for sale in Canada.
So many questions,..so few answers. This is all speculation on my part based on my limited understanding of internal rifle ballistics.
Someone with more knowledge or testing facilities who could enlighten us as to the actual pressure curve with this ammo versus say AE or W-W would be much appreciated. None of it in our stock will see my new NEA's 10.5" poly rifled barrel .
On a lighter note, I had started a controlled side by side comparison for 50 rounds each from all ammo makes in my box, after reading all the complaints on 223Nork back in august/september firing from a bench at 50yards and chronying all while measuring 5, ten shot, groups. All went well till I shifted to the 3rd target using the Nork ammo first up. It struck my chrony, at an average to that point of 2957@15feet in a 14.5" tube and we all know what a 55gr does at 15feet on striking steel. I did realize however you could hide behind a steel chromed chair leg and possibly survive an attack with 55grfmj's Nork LOL.
I noticed two weeks ago, the powder in a round that had been driven back into the case while chambering in an Armalite M15A4, possibly from undersize or lack of proper crimp or both, and the dumped powder appeared to be of a "blended" type, with different grain sizes and different types mixed in. In particular flattened ball and spheroidal ball grains in the same charge.
I witnessed the first keyhole as well at 50 yards from my son's new 1/9" twist Armalite with less than 250 rounds fired total and while using 223Nork. We had maybe 400 rounds of it up to this point no problems. The bullet had yawed a full 90 degrees and struck completely sideways while passing through a single target sheet paper. I measured all rounds left in the CJ 95 lot#26 we have on hand and did not find any under .224". The one that keyholed, had it been driven back into the case, and deformed like the one we found, and had to jump long into the leade while off center and deformed would have made a nasty barrel whip on acceleration and most likely would be un-stabilizable, hence the keyhole. Just speculation for others versed in internal/external ballistics to ponder and rebutt.
With the unknown powder type and reports of undersized bullets(.220" vs .224"), I'm going to hold off on buying anymore of this ammo in the short term. I have put over 800 rounds of Nork 762NATO through my M-14 with no issues noticed yet.
Again as I've stated many times in other threads on Chinese ammo,... what the pressure curve is and flame temp in the throat and how the velocities are obtained in regards to weight of charge and burn rates as compared to NATO spec ammo is anyone's guess.
This in itself is not a bad thing altogether, as many different world wide ammo makers use a variety of their proprietary powders or others, to obtain spec velocities for a given cartridge. Some ammo 's are harder on certain gas guns actions or barrels than others, this is a fact. Look at MkVII .303 Ammo loaded with Cordite versus more modern day nitro cellulose for instance. Same velocities at the business ends, but Cordite being far harder on throat erosion.
The trade off I guess is in absolute economics. If an AR barrel is worn beyond acceptable accuracy after say 5000 rounds of Nork that cost 1200 dollars as compared to 8,000-10,000 rounds while using AE for a cost of 3200-4000 dollars, and if the gun's functionality properly and accuracy was acceptable, would'nt a new 300 dollar barrel still be the cheapest option? Finding and having a new barrel installed on a Swiss Rifle as in Steve's case would be far more costly, thus you need to weigh this all out, if indeed the Nork ammo is proven to be anymore abrasive on throats than any other bulk .223/556 we have for sale in Canada.
So many questions,..so few answers. This is all speculation on my part based on my limited understanding of internal rifle ballistics.
Someone with more knowledge or testing facilities who could enlighten us as to the actual pressure curve with this ammo versus say AE or W-W would be much appreciated. None of it in our stock will see my new NEA's 10.5" poly rifled barrel .
On a lighter note, I had started a controlled side by side comparison for 50 rounds each from all ammo makes in my box, after reading all the complaints on 223Nork back in august/september firing from a bench at 50yards and chronying all while measuring 5, ten shot, groups. All went well till I shifted to the 3rd target using the Nork ammo first up. It struck my chrony, at an average to that point of 2957@15feet in a 14.5" tube and we all know what a 55gr does at 15feet on striking steel. I did realize however you could hide behind a steel chromed chair leg and possibly survive an attack with 55grfmj's Nork LOL.
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