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When you work up a load for your rifle, you will have to stop increasing the powder charge at some point when you reach dangerous pressures.
When term "Too Hot" means dangerous pressure levels have been reached, but each rifle is a bit different. What may be a too hot of a load in my rifle may work safely in your rifle. You will get the signs, flattened and cratered primers, pierced primers, galling in the case head-ejector mark imprints and blown primers.
As an example, when the Hornady TAP ammo became popular, I decided to try some for our team. I contacted Hornady's L/E department. They shipped me a few boxes of the 308, 155 gr. and 168 gr. TAP ammo.
The ammo shot great in our bolt rifles, but when I ran it in a SR-25, It was blowing primers. On a few of the rounds, the primer fell out of the empty brass. There was also heavy galling of the case head from the ejector. This ammo was not suitable for the SR-25. The brass was not reloadable due to the primer pockets expanding excessively.
I contacted Hornady, sent then some fires cases and the rest of that lot of ammo back for their testing. I was told they would look into it.
I was sent a newer lot of the 168 ammo to try. This ammo ran fine in the rifle. We bought some of the ammo and it ran fine in the SR-25's. I don't know what they did to tweak the ammo, but they did. I was also told, I wasn't the only one to bring up the issue.
That first test lot of ammo was safe in a bolt gun was not safe in a gas gun.
If you can find a copy of the Sierra 5th edition loading manual, they provide loading data in the .223 Remington for bolt guns and for gas guns(tested with an AR-15). If you compare the powder charges for the 69 gr. Match bullet and the 80 gr. Match bullet (I don't know why they didn't test the 77 gr. bullet in the bolt gun). You will see the bolt gun actually can take higher powder charges(of the same powder) than the AR-15 does.
When they are loading, they aren't jamming the bullet into the lands.
The point is, the Military Factory loaded M-193 ammo and now M-855 ammo has a bullet ogive profile at a COL that causes pressure issues in a SAAMI spec .223 Remington chamber due to the shorter throat in the .223 Remington, but it will run at safe pressures in the 5.56 NATO chamber.
If you have a bolt gun in .223 Remington and want to shoot Military spec, factory loaded ammo, you can get your .223 Remington chamber reamed to a Wylde specs. Problem solved.
As with everything that has been said before, when you are hand loading, you load up to what your rifle will handle safely.
As far as your question on a Mk 262 clone, Sierra lists a load with their 77 gr. Matchking with a maximum load of 24.0 grains of TAC, showing a velocity of 2950 FPS our of their 20" Colt Ar-15A2 HBAR test rifle.
The whole point to the Mk 262 ammo is to give our troops a better terminal bullet than the M-855 out of the M-4.
When term "Too Hot" means dangerous pressure levels have been reached, but each rifle is a bit different. What may be a too hot of a load in my rifle may work safely in your rifle. You will get the signs, flattened and cratered primers, pierced primers, galling in the case head-ejector mark imprints and blown primers.
As an example, when the Hornady TAP ammo became popular, I decided to try some for our team. I contacted Hornady's L/E department. They shipped me a few boxes of the 308, 155 gr. and 168 gr. TAP ammo.
The ammo shot great in our bolt rifles, but when I ran it in a SR-25, It was blowing primers. On a few of the rounds, the primer fell out of the empty brass. There was also heavy galling of the case head from the ejector. This ammo was not suitable for the SR-25. The brass was not reloadable due to the primer pockets expanding excessively.
I contacted Hornady, sent then some fires cases and the rest of that lot of ammo back for their testing. I was told they would look into it.
I was sent a newer lot of the 168 ammo to try. This ammo ran fine in the rifle. We bought some of the ammo and it ran fine in the SR-25's. I don't know what they did to tweak the ammo, but they did. I was also told, I wasn't the only one to bring up the issue.
That first test lot of ammo was safe in a bolt gun was not safe in a gas gun.
If you can find a copy of the Sierra 5th edition loading manual, they provide loading data in the .223 Remington for bolt guns and for gas guns(tested with an AR-15). If you compare the powder charges for the 69 gr. Match bullet and the 80 gr. Match bullet (I don't know why they didn't test the 77 gr. bullet in the bolt gun). You will see the bolt gun actually can take higher powder charges(of the same powder) than the AR-15 does.
When they are loading, they aren't jamming the bullet into the lands.
The point is, the Military Factory loaded M-193 ammo and now M-855 ammo has a bullet ogive profile at a COL that causes pressure issues in a SAAMI spec .223 Remington chamber due to the shorter throat in the .223 Remington, but it will run at safe pressures in the 5.56 NATO chamber.
If you have a bolt gun in .223 Remington and want to shoot Military spec, factory loaded ammo, you can get your .223 Remington chamber reamed to a Wylde specs. Problem solved.
As with everything that has been said before, when you are hand loading, you load up to what your rifle will handle safely.
As far as your question on a Mk 262 clone, Sierra lists a load with their 77 gr. Matchking with a maximum load of 24.0 grains of TAC, showing a velocity of 2950 FPS our of their 20" Colt Ar-15A2 HBAR test rifle.
The whole point to the Mk 262 ammo is to give our troops a better terminal bullet than the M-855 out of the M-4.
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