Miltary brass and higher pressure loads.

[223AI]

Following on from a couple of threads recently I am working on a 69gr load for my 1:9 0.223 that i am basically looking to mimic 69 gr fmj 5.56 x 45 nato ammo so I can shoot the 0.223 out as far as possible at Bisley.

Obviously the Nato offerings operate at higher pressure but these are still suitable as far as I am aware for civilian rifles chambered in 0.223 rem.

If therefore I am trying to get somewhere near this load am I better off using commercially available more roomy 0.223Rem brass so I can get higher powder charges in or would I be better off using surplus brass (I've got lots of GGG now after various donations) which will develop the same pressure with less powder due to its thicker walls but could potentially cope with slightly higher pressures.

Genuine query as I am about to start load development using 69gr TMKs, Fed 205 primers and (?) brass.

Answers on a post card please

[taz2]

Well,despite my previous postings advising people to never use other peoples' loads, the 'standard' 69smk load is 24 To 24.5 grains of something like Re15 or Viht140 or similar.
You might like to try 77smk-- I always got on better with them in my PSS. you could keep the powder at the same amount, or slightly less. I have never seen an improvement by adding more powder, in fact groups get worse. Smk bullets seem to like around 2750-2850 fps to function well. The added bonus is that you can load them mag length, they're designed to jump. They will do 900 yds easily at those loadings.

[tacfoley]

And as an aside......

The significant difference between the .223 Rem and 5.56 NATO lies in the rifles, rather than the cartridges themselves. Both the .223 and 5.56 rounds will chamber in rifles designed for either cartridge, but the critical component, leade, will be different in each rifle.

The leade is the area of the barrel in front of the chamber prior to where the rifling begins. This is where the loaded bullet is located when a cartridge is chambered. The leade is frequently called the “throat.”

On a .223 Remington spec rifle, the leade will be 0.085”. This is the standard described by the Sporting Arms and Ammunition Manufacturers’ Institute, Inc. (SAAMI). The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.

A shorter leade in a SAAMI spec rifle creates a situation where the bullet in a 5.56 NATO round, when chambered, can contact the rifling prior to being fired. By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased, creating the danger of a ruptured case or other cartridge/gun failure.

The reverse situation, a .223 Rem round in a 5.56 NATO gun, isn’t dangerous. The leade is longer, so a slight loss in velocity and accuracy may be experienced, but there is not a danger of increased pressures and subsequent catastrophic failure.

How serious is the danger of firing 5.56 ammo in .223 guns? Dangerous enough that the SAAMI lists 5.56 military ammo as being not for use in .223 firearms in the technical data sheet titled “Unsafe Firearm-Ammunition Combinations.”

tac

[223AI]

And as an aside......

The significant difference between the .223 Rem and 5.56 NATO lies in the rifles, rather than the cartridges themselves. Both the .223 and 5.56 rounds will chamber in rifles designed for either cartridge, but the critical component, leade, will be different in each rifle.

The leade is the area of the barrel in front of the chamber prior to where the rifling begins. This is where the loaded bullet is located when a cartridge is chambered. The leade is frequently called the “throat.”

On a .223 Remington spec rifle, the leade will be 0.085”. This is the standard described by the Sporting Arms and Ammunition Manufacturers’ Institute, Inc. (SAAMI). The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.

A shorter leade in a SAAMI spec rifle creates a situation where the bullet in a 5.56 NATO round, when chambered, can contact the rifling prior to being fired. By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased, creating the danger of a ruptured case or other cartridge/gun failure.

The reverse situation, a .223 Rem round in a 5.56 NATO gun, isn’t dangerous. The leade is longer, so a slight loss in velocity and accuracy may be experienced, but there is not a danger of increased pressures and subsequent catastrophic failure.

How serious is the danger of firing 5.56 ammo in .223 guns? Dangerous enough that the SAAMI lists 5.56 military ammo as being not for use in .223 firearms in the technical data sheet titled “Unsafe Firearm-Ammunition Combinations.”

tac

Thanks for that, I thought there was difference in that SAAMI pressure for .223 rem is 55,114 PSI and I thought the 5.56x45 pressure is different, evidently it's not, the CIP max is measured differently. I guess I should not have put GGG through my rifle on sunday! Having said that it would seem my .223 has quite a long throat as with 69 gr TMKs reach a COL of 2.36" before they touch the lands.

With regards Taz's post the load I've worked on is indeed 24.2 grains of N140 under either an SMK it TMK 69gr, best results with SMKs at 3/4 moa. I have however decided to give the TAC a go as I'd like to save my N140 for the .308 and I have a pound and a half of Tac sat there doing nothing.

So I'm just wondering, essentially, thick brass or thin?

PS I would guess the 77s will be too long for my 1:9

[taz2]

Thanks for that, I thought there was difference in that SAAMI pressure for .223 rem is 55,114 PSI and I thought the 5.56x45 pressure is different, evidently it's not, the CIP max is measured differently. I guess I should not have put GGG through my rifle on sunday! Having said that it would seem my .223 has quite a long throat as with 69 gr TMKs reach a COL of 2.36" before they touch the lands.

With regards Taz's post the load I've worked on is indeed 24.2 grains of N140 under either an SMK it TMK 69gr, best results with SMKs at 3/4 moa. I have however decided to give the TAC a go as I'd like to save my N140 for the .308 and I have a pound and a half of Tac sat there doing nothing.

So I'm just wondering, essentially, thick brass or thin?

PS I would guess the 77s will be too long for my 1:9

Not at all! I assume you meant heavy rather than long? Either way they should be ok. My PSS was 1:9 and actually liked the 77s better. You can load them mag length too---- they're designed to 'jump'. As it is, If you go for thicker brass, you will need to reduce your powder by 1/2 to 1 full grain. Other than cost of brass, I would venture there's no advantage to mil brass. In fact, prep involved with mil brass is a real faff.

[223AI]

Not at all! I assume you meant heavy rather than long? Either way they should be ok. My PSS was 1:9 and actually liked the 77s better. You can load them mag length too---- they're designed to 'jump'. As it is, If you go for thicker brass, you will need to reduce your powder by 1/2 to 1 full grain. Other than cost of brass, I would venture there's no advantage to mil brass. In fact, prep involved with mil brass is a real faff.

Well I was under the impression that it was length that made the difference to stability in different twist rates and its the fact that heavier bullets are generally longer that means everyone refers to the weight hence i can't shoot 36gr non toxic varmint grenades in my 1:16 hornet as they are long for weight due to the lack of lead but but can shoot stumpy 35gr v-max really well.

Either way I guess weight and length are pretty interchangeable particularly with bullets of standard construction.

I here what you're saying ref milsurp and prep but its what I've been using with the 69gr (at 24.2gr with no pressure signs) so I have 100 which have had crimps remove, primer pockets and flash holes uniformed, to be honest if Guesty's offer from sunday stands then it will be federal brass if i go down the commercial brass route which is also crimped in 0.223 so it will be more work! Not that its a big issue as I just sit in front of the telly to do the crimp and primer pockets, it doesn't require much concentration in comparison to most of the other processes involved in loading.

Interesting to hear the 77s (assuming SMKs?) are stabilising in your 1:9 though, i was under the impression that 69 was the practical limit, what sort of velocity are you pushing them at? Either way I'll not be buying any for a while as I just bought 300 69gr TMKs

[taz2]

Well I was under the impression that it was length that made the difference to stability in different twist rates and its the fact that heavier bullets are generally longer that means everyone refers to the weight hence i can't shoot 36gr non toxic varmint grenades in my 1:16 hornet as they are long for weight due to the lack of lead but but can shoot stumpy 35gr v-max really well.

Either way I guess weight and length are pretty interchangeable particularly with bullets of standard construction.

I here what you're saying ref milsurp and prep but its what I've been using with the 69gr (at 24.2gr with no pressure signs) so I have 100 which have had crimps remove, primer pockets and flash holes uniformed, to be honest if Guesty's offer from sunday stands then it will be federal brass if i go down the commercial brass route which is also crimped in 0.223 so it will be more work! Not that its a big issue as I just sit in front of the telly to do the crimp and primer pockets, it doesn't require much concentration in comparison to most of the other processes involved in loading.

Interesting to hear the 77s (assuming SMKs?) are stabilising in your 1:9 though, i was under the impression that 69 was the practical limit, what sort of velocity are you pushing them at? Either way I'll not be buying any for a while as I just bought 300 69gr TMKs

Fair point about length versus weight. They sort of go hand in hand---generally. Yes, they were smk. I'm not sure about the length being the deciding factor though. After all the various forms of,say, 30 cal smk boast different profiles lengthwise but all stabilise at the same weight.
If you've got some prepped brass, stick with it. I think I was getting about 2750-2800 with the 77 gn. I've just had the PSS rebarelled with a 1in7. I'm using 90gn vld Bergers in that. They're starting to show promise. The old barell was giving sub 1/2 minute groups regularly, the new one is now, after some running in, starting to match that.

[sarge4318]

PS I would guess the 77s will be too long for my 1:9

77SMKs can be loaded to mag length for an AR. The 77s are very jump tolerant and it is the magazine and not the chamber that will dictate the OAL in this type of rifle. So you should be able to load to your rifle without problem.
The 77s should work well in the 1:9" but it is near the limit of stabilising and I have seen at least one barrel have trouble doing so.