Based on the measurements I've done I should have at least 10 thousandths of jump to the rifling. Either way, based on what I've seen here I think I'm just going to tune my gas block and back off my starting load by .7 gr and work up from there.
Weird pressures with cfe 223
- Thread starter Bvin91
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Get a Hornaday book with service rifle data gas guns do not load the same as bolt guns less pressure.
lordpaxman
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Welcome to THR @Bvin91 .
I’ve not seen the ADI headstamp before, is this military brass? If so, it’s internal case volume could be less than the WIN volume and could account for additional pressure.
How are you measuring setback and/or neck tension? Could you safely chamber a round and eject it and measure?
Regarding your digital scale, I’m a fan of them, not that I trust them entirely, but do you have check weights so you can verify it’s operation at about the weights of your charges? I use a beam balance to also verify the check weight.
Also following as CFE223 is one of the powders I’ve wanted to try, although it’s be for your smaller cousin.
Have you also just searched your powder’s lot number and make sure it’s not recalled? Good luck.
I’ve not seen the ADI headstamp before, is this military brass? If so, it’s internal case volume could be less than the WIN volume and could account for additional pressure.
How are you measuring setback and/or neck tension? Could you safely chamber a round and eject it and measure?
Regarding your digital scale, I’m a fan of them, not that I trust them entirely, but do you have check weights so you can verify it’s operation at about the weights of your charges? I use a beam balance to also verify the check weight.
Also following as CFE223 is one of the powders I’ve wanted to try, although it’s be for your smaller cousin.
Have you also just searched your powder’s lot number and make sure it’s not recalled? Good luck.
Your chrono number is off, in my opinion. I will explain why I think so.
From the one case head stamp photo you posted, it appears you do not have an over pressure condition. The corners of the primer appear nice and rounded still, and it doesn’t look like the primer flowed into the firing pin hole. Look closely at your case to confirm my observations of this one photo.
Edit: the photo posted by @TEXASJD at the same time of my post shows another thing to look for that your photo doesn’t show.
At 68,000 psi, I would expect a flattened primer with firing pin flowage, not rounded / radiused corners but sharp / square, like the cup side of the primer.
My experience -
In 358 Winchester (308 necked up) using a 200 grain bullet, I cannot get enough CFE223 in the case to create an overpressure condition. Just last week I was testing 53 grains of CFE223. 53 grains dropped in fills the case half way up the neck. I then taped/settled the powder to the bottom of the neck before I seated the 200 grain bullet. My velocities and pressure signs were nearly identical to my 45 grain IMR-3031 / 200 grain bullet load which is a mild 45k CUP load.
Figure out a way to test your chrono (shoot 22 over it for 1080 or 1250 fps is one idea) retest your load x3 and do a detailed inspection of the fired brass.
From the one case head stamp photo you posted, it appears you do not have an over pressure condition. The corners of the primer appear nice and rounded still, and it doesn’t look like the primer flowed into the firing pin hole. Look closely at your case to confirm my observations of this one photo.
Edit: the photo posted by @TEXASJD at the same time of my post shows another thing to look for that your photo doesn’t show.
At 68,000 psi, I would expect a flattened primer with firing pin flowage, not rounded / radiused corners but sharp / square, like the cup side of the primer.
My experience -
In 358 Winchester (308 necked up) using a 200 grain bullet, I cannot get enough CFE223 in the case to create an overpressure condition. Just last week I was testing 53 grains of CFE223. 53 grains dropped in fills the case half way up the neck. I then taped/settled the powder to the bottom of the neck before I seated the 200 grain bullet. My velocities and pressure signs were nearly identical to my 45 grain IMR-3031 / 200 grain bullet load which is a mild 45k CUP load.
Figure out a way to test your chrono (shoot 22 over it for 1080 or 1250 fps is one idea) retest your load x3 and do a detailed inspection of the fired brass.
Blue68f100
Member
Primer flow is a product of the mfg using wide clearance between the bolt hole and firing pin. I've had the same problem with starting loads piercing the primers. There should only be 0.002" max clearance between the FP and hole. Any more than that you get the flow. Mine was at 0.004" and would blow a primer >25% pf the time. I contacted the mfg, returned it and the replacement was worst. So I no longer buy their products or recommend them. I ended up replacing the bolt with a JPI HP bolt, problem solved. I did finally sleeved the bolt to proper clearance so I have a spare if needed.
My neighbor had problem with the CFE-223 a while back. I think his lot was hotter than it should have been.
Like the others I do not see HP signs. What I see is a bolt with an over size hole or under size FP.
My neighbor had problem with the CFE-223 a while back. I think his lot was hotter than it should have been.
Like the others I do not see HP signs. What I see is a bolt with an over size hole or under size FP.
That makes sense. This was my 1st time using this chrono, so I guess next range trip I'll take my old one too and compare numbers with some factory loads.
This is the first time its happened, so maybe just the fact that it was way over gassed caused it. Either way, my brothers 308 has a jp fmos bolt and carrier so I'll make sure I grab that and bring it along for next time just in case I run into the same issue.
FROGO207
Member
I am not a fan of digital scales when reloading. That said it might be a tolerance stacking thing. The primers being those Winchester universal ones, brass that has less internal volume than the stuff used at the book publishers, scale allowed a generous load of propellant, and different lot of propellant/ kind of bullet.
Still it looks posibly overloaded so keep us informed. The shooting of some factory rounds and closly inspecting for primer flow and velocity is a good idea too.
Still it looks posibly overloaded so keep us informed. The shooting of some factory rounds and closly inspecting for primer flow and velocity is a good idea too.
AJC1
Member
If you have the resources I would settle the gun in on factory ammunition. Get everything working as it should, gas adjustments and then test your loads. Working against your rifle while testing will give you weird and hard to interpret indications.
Dale Alan
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Good advice right there . Without a good base to start from you could be chasing a problem that is not there .
Nature Boy
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Bigger bore nets less pressure compared to a .308
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100% agree. If I had 243 / 308 experience I would have shared. I shared what I had.
denton
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If you used a standard primer, inversion of the firing pin dent is likely at 5.56 pressures. One of the thicker primers, such as the CCI SRM, will work best.
the only thing I can say is that in the long run, human error is far more common than mechanical repeatability. Hand weighing charges will almost always be more likely to give you an extreme over/under charge. Humans have a natural bias to see the number they're looking for.
Could be something else too. My best guess if your certain of the charge, and the others were okay, is bullet setback. I had a .300 AAC that was blowing primers, and the pocket too stretched to reuse. Load was verified, everything was good, neck tension was good too. Finally concluding there could be nothing else, I buffed my expander down to .3065". Hundreds of those loads later, no more pressure signs at all. The original expander was up to spec, and each round did not more under about 20lbs of force. I would not expect that much force on the bullet if the round actually hit the feedramp, but evidently it can.
Could be something else too. My best guess if your certain of the charge, and the others were okay, is bullet setback. I had a .300 AAC that was blowing primers, and the pocket too stretched to reuse. Load was verified, everything was good, neck tension was good too. Finally concluding there could be nothing else, I buffed my expander down to .3065". Hundreds of those loads later, no more pressure signs at all. The original expander was up to spec, and each round did not more under about 20lbs of force. I would not expect that much force on the bullet if the round actually hit the feedramp, but evidently it can.
Bwana John
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I had high pressure issues loading CFE223 in a 7.62 NATO rifle.
It was a very thin line between no problems and extremely high pressure signs.
It was a very thin line between no problems and extremely high pressure signs.
CFE223 can be touchy in a gas gun.I had an AR-10 in 308 do the same thing for me,only worse.It actually opened the primer pocket up so much that a primer could move around in it.That was 1 grain above the starting load for a 178 grain ELD. I think it was caused by the bullet slipping back when it was chambered.Not 100 percent sure,but it was the 3rd shot of a 5 shot group and I stopped right then.I KNOW the charge was right.
Coyote conquest
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I would back off a half grain to see what happens just to rule high pressure out.
I'm not sure how being over gassed could cause that. It could just be soft primer cups. With out trying a mag or military primer, there isn't a way to know. I have the Hornady 11th and CFE isn't in the service rifle data.
I'm not sure how being over gassed could cause that. It could just be soft primer cups. With out trying a mag or military primer, there isn't a way to know. I have the Hornady 11th and CFE isn't in the service rifle data.
243winxb
Member
Here is another 308 Auto, same powder, with pressure problems.https://www.ar15.com/forums/armory/...-/42-524757/?r=-1&page=1&anc=5510355#i5510355
Could be the powder is a hot lot?
Could be the powder is a hot lot?
KP Texan
Member
Yep, that's me. I was just about to post in here and say it's almost exactly like what happened to me yesterday. What's interesting is that I was also running some IMR 4064 loads with recommended charges and all other factors being identical (bullet, case, primer COAL), and they performed pretty much as the data said they should (or maybe even slightly slower).
My rifle is pretty well tuned on 7.62 Federal XM80 right now (149gr FMJ @ 2759fps from my barrel), so I was likely overgassed with these loads.
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