Raised Ring at Base of .223 case?

[jlow]

All of the points above are valid but... I sound like a broken record here but with an AR unless the gas port is blocked, the bolt may be unlocking before pressure is down to safe levels. The gas port's only regulation is its location and size. It takes as much gas as it can handle.

Testing over a chrono will show the differences in velocities but the inherent design of the rifle adds a huge variable to the experiment.

Scott

I think we both sounds a bit like a broken record. ;D I would not say the gas port is not a potential problem, just did not comment on it as I have less experience with it. It’s really up to the OP to look into this. Frankly I am happy to give advice if I think it is helpful but any hands on work would be over the top for me as I have my own problems to address.

 

[BoydAllen]

Since I was able to rise, and become vertical upon waking this morning, and move around with no serious discomfort, I am without serious problems. Getting back to the subject, put a little less powder in your Lapua cases and your problem should be solved. Case closed. Next!

 

[CatShooter]

My suggestion is if someone thinks this case softness idea is real and they want to champion/proof it, test some cases with hardness tester and report back.

Pardon the mess - it always looks like this in the spring - Martha Stewart's maid couldn't make it, and the woodchucks are calling...

My $2,500 Ames Hardness Gauge -- it is FAA certified and approved for testing aircraft engine parts (it does NOT get any better than that!)

I measured four cases picked at random.

LC 2008 5.56mm
Lapua 223 Match
Winchester 223
Remington (R-P) 223

The actual measurements were (.062"x100kg, Rockwell "B")

LC 2008 = 96

Lapua 223 Match = 86

Winchester 223 = 69

Remington "R-P" = 49

For all you guys that have believed that Winchester cases were tougher than Remington... you are vindicated, they are a lot tougher!...

... but LC and Lapua are the "The pick of the litter"!

The difference between Lake City and Lapua is NOT enough to account for the problems that the OP is talking about...

... but the difference between LC and commercial cases IS enough to account for what that Pesky Ed is talking about.

(Ain't modern telephones wunnerful fer pictures ??)

 

[bigedp51]

... but the difference between LC and commercial cases IS enough to account for what pesky Ed is talking about.

Dear CatShooter

I don't think of myself as "pesky" BUT..............................
I did graduate first in my class from the "Attila the Hun school of diplomacy." ;D

I don't have your expensive Ames Hardness Gauge so I use a cheap homemade web thickness gauge on my .223/5.56 cases that I shoot in my AR15s.

The base of Lake City and commercial military contract 5.56 ammunition is harder and thicker in the web.

 

[BoydAllen]

Catshooter,
Magnificent! Well done.

 

[jhord]

I have no idea what the last bunch of junk is about, but the hardness test echoes everything I have seen shooting AR's competitively for a few years now. Winchester brass is junk, Lapua holds up very, very nicely, and Lake City is the first to split. I have never ever had a ring form around the head so I think it's possibly more than a brass issue. YMMV.

 

[CatShooter]

"... the hardness test echoes everything I have seen shooting AR's competitively for a few years now. Winchester brass is junk, Lapua holds up very, very nicely, and Lake City is the first to split."

The hardness test has nothing to do with quality or splitting. It is only a measurement of the hardness of the case head... which related to head expansion under pressure.

Splitting is an annealing issue... anneal the cases and they will not split.

And quality is a money issue... you cannot get $1.05 each quality for 30¢ each...

... and neither has anything to do with case head hardness.

 

[jhord]

I realize that, but I'd bet if you ran the same test on the necks of virgin brass, you might get the same results. Either way, I don't care. I've fired a lot of Lapua brass in an AR, thru many cycles, and I don't think the OP's issue is the brass... at least solely the brass.

 

[CatShooter]

I realize that, but I'd bet if you ran the same test on the necks of virgin brass, you might get the same results. Either way, I don't care. I've fired a lot of Lapua brass in an AR, thru many cycles, and I don't think the OP's issue is the brass... at least solely the brass.

I don't think so either... I am inclined to thing it is gas port related - either size or timing (both interact with each other).

 

[bigedp51]

I realize that, but I'd bet if you ran the same test on the necks of virgin brass, you might get the same results. Either way, I don't care. I've fired a lot of Lapua brass in an AR, thru many cycles, and I don't think the OP's issue is the brass... at least solely the brass.

I don't think so either... I am inclined to thing it is gas port related - either size or timing (both interact with each other).

The OP has a stock rifle without a adjustable gas block and you and others are saying its gas port related when actually its the burning rate of the powder. And "HOW" much the OP was putting in his cases.

And if you haven't noticed the OP thanked us yesterday and left this posting, so there is only one thing left to do........................

And thats to ask the resident Lapua brass expert what to do next. :
(meaning drop another bazinga on him) ;D

I for a fact use Lapua 223 brass in my AR-15 with an over max load and don’t have a problem like the OP has found.

 

[CatShooter]

I realize that, but I'd bet if you ran the same test on the necks of virgin brass, you might get the same results. Either way, I don't care. I've fired a lot of Lapua brass in an AR, thru many cycles, and I don't think the OP's issue is the brass... at least solely the brass.

I don't think so either... I am inclined to thing it is gas port related - either size or timing (both interact with each other).

The OP has a stock rifle without a adjustable gas block and you and others are saying its gas port related when actually its the burning rate of the powder. And "HOW" much the OP was putting in his cases.

And if you haven't noticed the OP thanked us yesterday and left this posting, so there is only one thing left to do........................

And thats to ask the resident Lapua brass expert what to do next. :
(meaning drop another bazinga on him) ;D

I for a fact use Lapua 223 brass in my AR-15 with an over max load and don’t have a problem like the OP has found.

The fact that the rifle is stock does not mean it is not port pressure timing. I once had a love affair with an M-14, and I learned more than I wanted to know about picking powders to match the port pressure requirments.

It required 12,000 to 14,000 psi - any more (slow burning powder) and you beat the crap out of the gun, and less and you see high pressure signs on the cases, but the rifle will not completely cycle.

Speer is the only manual to address this stuff.

 

[bigedp51]

CatShooter

Your M14/M1A was more sensitive because of the shorter gas system meaning the location of the gas port and its higher port pressure compared to a M1 Garand port further down the barrel.

The AR15 can fall into the same category "BUT" the OP has a rifle gas system further down the barrel.

What I'm about to say CatShooter is not in any way meant to be insulting to you or anyone else making comments about the AR gas system.

I do not think the gas system had anything to do with the OPs problem period. I think and I'm guessing it was just a simple matter of the Lapua case being loaded too hot. I get the gut feeling he was shooting this load in Lake City brass and thought if he switched to Lupua his groups would become bug size.

Again this is just guesswork but I get the feeling the OP just didn't understand what he was actually looking at with his cases. Meaning chamber pressure too high for the type brass in a larger diameter military chamber.

Below is a Quickload guesstimate of the chamber pressure and velocity of my 25 grain H335 practice load in Lake city cases with 30.6 grains of H2O case capacity.

Below is the same load in a case with only 28.8 grains of H2O case capacity and over 6,000 psi higher chamber pressure.

Lake City cases have MORE case capacity than any other .223/5.56 case, BUT how many times have you seen someone say military cases have less capacity because they have thicker case walls.

The OP and his Lapua cases were telling him a story and he failed to grasp the plot and where the story was taking him.

Both the .303 British cases below are once fired factory loaded ammunition and never reloaded, and both were fired in the same Enfield rifle. The case on the left has a larger base diameter and the case walls are .010 thicker in the base web area. The only thing wrong with the HXP case on the right is the brass is slightly softer and it has a smaller base diameter. Meaning it had further to stretch to meet the chamber walls, "BUT" the ring around the case means nothing, and the case did not stretch or thin at this point.

Bottom line, sometimes a ring around the case is simply cosmetic and nothing to worry about, but you always investigate what is causing the problem and come up with an answer.