Max Pressure for 223 in GRT
- Thread starter Timon
- Start date
At this point, I’m really not, other than just looking for pressure signs in the brass. I’m currently working on with GRT and was simply wondering what others are using for the max pressure on 223 rounds. I have it set at 55,000, but was curious if others were using a higher value.
jelenko
Gold $$ Contributor
Interesting. In my copy of GRT, it shows max pressure of 65K for 223.
Because the originator of GRT was from Germany, I've assumed he was using CIP.
ETA: Sorry, I'm using a custom drawing for 223 Wylde - which has a max PSI of 65K
When choosing the 223 SAAMI chamber, the max pressure shows as 55K PSI.
Because the originator of GRT was from Germany, I've assumed he was using CIP.
ETA: Sorry, I'm using a custom drawing for 223 Wylde - which has a max PSI of 65K
When choosing the 223 SAAMI chamber, the max pressure shows as 55K PSI.
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Bladesmith
Silver $$ Contributor
It almost seemed like some of the cartridges are measured to SAAMI and some are CIP if memory serves. Or at least I thought it might have been last time I fooled with it
I may be entirely wrong though. Wife says it happens a lot with me
I may be entirely wrong though. Wife says it happens a lot with me
The chambering of your rifle barrel will be the guide. If it’s chambered in 223 Remington, I’d stay at 55,000 psi. If it’s been modified with a throat reamer, it’s 223 Wylde or something else that has a 1 1/2 degree leade angle, you can use 60,000.
VihtaVuori has an excellent loading phone application and a lot of loads for N133. I'd use the app and respect the max load. Check your chamber though.
I have a 5.56 x 45 chambered rifle and use .223 (5,56 x 45 nato) in GRT. I pushed a bit past VV's max load close to 62366 psi and started to get flat primers. I then backed off 5% and was right around the VV's suggest max load for .223 rem (not 5.56x45). GRT has me at 57,750 which falls between the 2 different chambers and is where i expected to be. If I had a .223 chamber I'd use .2232 Rem (SAAMI) and wouldn't intentionally go above 55,000.
I have a 5.56 x 45 chambered rifle and use .223 (5,56 x 45 nato) in GRT. I pushed a bit past VV's max load close to 62366 psi and started to get flat primers. I then backed off 5% and was right around the VV's suggest max load for .223 rem (not 5.56x45). GRT has me at 57,750 which falls between the 2 different chambers and is where i expected to be. If I had a .223 chamber I'd use .2232 Rem (SAAMI) and wouldn't intentionally go above 55,000.
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^^^^this^^^^^
As above. If it's chambered in .223 Rem stick to the SAAMI settings , there's very little to be gained pushing the 223 .
Just to add a little weight to this , a couple of years ago I got into a discussion on another forum regarding the same issue . It was my belief that as our regulations fall under CIP and are proofed accordingly then we should be safe to use 5.56 NATO ammo . There's no other way to put this ,I was wrong !" CIP I believe test pressure in the same way as NATO spec'd ammo is tested , at least for the 223 . However, there is no available data to confirm the 5.56s spec' , ammo that was tested on a YouTube channel was all over the place, some way over . Also , there are chambering differences to take into account.
Out of interest , I emailed 5 different rifle manufacturers and asked if they deemed it safe to run 5.56×45 NATO ammo through their rifles that are chambered in .223 Rem . Four said ,"No!"
I doubt I could find the emails now , I did post them at the time for everyone to see on Stalking Directory .
memilanuk
Gold $$ Contributor
Same kind of thing here... I recently ran an old standby 223 load - 50/52/55 gn bullet over 25-25.5 gn H335 - through GRT, and it was *well* below even the 223 SAAMI pressure 'limit'. It's going to be shot in a variety of barrels that are either 223 Wylde or some form of 'match' chamber where I'm pretty comfortable going much higher... but in this situation, the bullet does what I need (shoot small groups) at a reasonable speed. Good enough 
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GRT predicted the velocities of N133 extremely well but there were still some oddities. I did a primer test comparing CCI 450, CCI #41, Rem 7_1/2, and some unknown primer that came on brass from American reloading.
The 450s and 7_1/2 primers were 50-60 fps faster than #41 and the unknown primer. GRT was dead in the middle. When i punched the velocity data into GRT and ran OBT things got a lot closer to max pressure with the hotter primers. I'm not used to the small case of .223 so I'm learning that every tiny change is more impactful compared to a cartridge with larger volume like 270 wsm or .308. It's making the process a lot of fun. I'm finding that once i get a load dialed the shooting aspect isn't as much fun as the fiddling with a load.
My load is 22.92gr of N133 with a Barnes tsx 62 gr. Velocity is 2690 fps out of a 12.5" barrel. I need to tune seating depth but the above is getting me 0.8moa groups. GRT pressure is 57750.
223 Remington and 5.56x45 NATO are NOT the same chambering so they are not the same cartridge. They share a common case. The original 556 cartridge released for the M16 was pretty much the 223 Remington and interchangeable. The original 556 was not a NATO standard round and was based on the 55gr FMJ bullet. In the late 1970's nato issued a request for a round that would be more capable of light armor penetration. They started with the 556 round and developed a 62gn bullet (SS109) with a steel penetrator which made the bullet longer by about 0.03" if I remember correctly This required moving the throat of the original 556 and at the same time they changed the throat angle to the more modern 1.5 degrees. This work was performed by FN and therefor was done along the lines of the CIP standards which was transducer based. It was also designed based on metric dimensions and not English. The original 223 Rem and 556 were developed in the US and used US Army and SAAMI standards at the time and were based on CUP (Copper Units of Pressure). There is also a requirement for port pressure in the military rounds. Bottom line is the two chambers have different dimensions and are governed by different Standards for pressure measurements. The only thing they share is a common case. There is no way a rifle manufacturer is going to tell you to blindly use a cartridge designed with different chamber dimensions is safe to use in a different chamber.
I never said they were the same chambering and alluded to such in my post .
However, always good to read a little more history on a chambering. Cheers
As for the 5 companies I emailed , CZ said "no "though an earlier post on AS quoted them as saying " yes ". I think it was Anschutz who said and I'm paraphrasing, it was safe to use 5.56 ammo in their 223 Rem chambered rifles as 5.56 and 223 are the same . Personally , I'd stick with 223 ammo in a 223 , why risk you're own well being and your rifle .
I should add , that I've included a caveat purely because whilst I've never heard of someone blowing up their 223 using 5.56 ammo , if someone were to do so I wouldn't want to be the guy who said it was okay to do so . There are in fact some who claim mil spec is identical to 223 and as such perfectly safe . Not really an issue over here , I've never come across surplus, though it may be available.
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The original question was how much is the max pressure for a .223 in GRT. In my opinion what SAAMI says.
In real life, why? Is your brass that expendable? Is your firearm expendable? Maximum pressure is bound to cause more wear on everything. The firearm will probably show less wear than anything else. Remember shooters wear out barrels.
The military may be pushing it to the max but I doubt it. There if it saves a life it is worth it. For civilians I can't see a few FPS making that much difference.
I knew a guy that said the reloading manual max charge was just a guideline. A few weeks later he asked me why the necks on the.223 loads were cracking. He was loading them too hot.
GRT is a simulation, hopefully it is close to the actual pressure the load will have. But it probably won't be exact. The bottom line is use good judgement.
Paul
In real life, why? Is your brass that expendable? Is your firearm expendable? Maximum pressure is bound to cause more wear on everything. The firearm will probably show less wear than anything else. Remember shooters wear out barrels.
The military may be pushing it to the max but I doubt it. There if it saves a life it is worth it. For civilians I can't see a few FPS making that much difference.
I knew a guy that said the reloading manual max charge was just a guideline. A few weeks later he asked me why the necks on the.223 loads were cracking. He was loading them too hot.
GRT is a simulation, hopefully it is close to the actual pressure the load will have. But it probably won't be exact. The bottom line is use good judgement.
Paul
In my original post, I was simply trying to find out what others were using for the max pressure on a 223. I was not trying to find out what the max pressure a 223 could take, just what are others using in GRT for the question of max pressure. I thank everyone for taking the time to respond to my question. From what I took in from the responses, 55k is the proper value for that item, so that’s what I’m using.
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