.223 Pressure Indications

slimjim · Posted: Sun Nov 06, 2011 3:29 am Post subject: .223 Pressure Indications

Dawgdad, shrpshtrjoe, and others could help me out with this one. I was inspecting my cases from Friday's range session for any signs of over-pressure. With the large rifle primers in my .270, the primers begin to flatten noticeable as pressure builds. When there is a ridge around the firing pin crater that I can catch my fingernail on, I know I am too hot for that rifle. I don't think the small rifle primers flatten out as much as the large primers do. The picture below is all the cases from my 70gr GMX load. The top left is 23.6 grains of Varget. The other 3 are 24.1 grains. The primers don't look like they are flattened much at all but all the primers from 24.1 grains have a ridge around the firing pin crater. Can anyone confirm this is too much pressure?

Vince · Posted: Sun Nov 06, 2011 3:54 am Post subject: Re: .223 Pressure Indications

I would say that the pressures are not excessive mate. The primers are not really flattened and the radius of the outer edge looks almost original. I've seen primers flattened a lot more than that in loads that were not delivering excessive pressure.

As for the slight ridge around the firing pin indentation, I would not consider it to be anything to be overly concerned about...the ridge is barely discernible. When that ridge is considerably bigger and really "flows" into the firing pin passage, then I would be concerned. What you have there is certainly a sign of pressure starting to climb, but not in my mind excessively...yet.

Just my call on what I can see mate...but then again, a pic doesn't always show the complete story.

Cheers, Vince

Ominivision1 · Posted: Sun Nov 06, 2011 5:54 am Post subject: Re: .223 Pressure Indications

From the photos they look fine, but it's impossible to judge pressure by primer appearance alone. Different makes or even batches can vary in cup hardness which of course makes it impossible. Take two cartridges from the same box and fire them in different rifles and the primers appearance can be very different. There are simply too many variables and if you believe that you can judge pressure from looking at primers alone then you only fooling your self and walking a very thin line.

Other things to look for hard case extraction after firing, appearance of other marks on the case head / base outside the web, carbon traces around primer. If your .223 suddenly recoils and sounds like a .30/06, you may want to investigate your load data no matter what the fired case looks like. Very Happy

Bushmaster · Posted: Sun Nov 06, 2011 8:56 am Post subject: Re: .223 Pressure Indications

You might also have a look at the firing pin hole in the bolt face. It might just be a bit over sized allowing the primer to show (indicate) cratering. If so. Not to worry.

Your primers do not indicate over pressure. Also Primers, even the flattened ones, do not indicate over pressure unless they are cratered, show metal flow, smokey (sooty) around the primer or a punctured primer are the indicaters of over pressure, but not flattened primers.

I would have a look at your firing pin and hole in the bolt face.

TRBLSHTR · Posted: Sun Nov 06, 2011 10:39 am Post subject: Re: .223 Pressure Indications

Ditto for what Vince,Omni,and Bushy said about the primers. Very Happy

HayCreek · Member Joined: Sep 10, 2011 Posts: 36 Location: Central ND

+1 to all above.

There are several indicators of overpressure. But, primer condition is not conclusive. What I see, here, is normal. When we speak of flattened primers, we mean the pronounced loss of radius on the primer cup.

slimjim · Posted: Sun Nov 06, 2011 2:21 pm Post subject: Re: .223 Pressure Indications

Thanks for all the feedback. I haven't loaded the .223 much nor pushed the upper bounds of performance. I'll keep a close eye as I progress.

Dawgdad · Posted: Sun Nov 06, 2011 4:20 pm Post subject: Re: .223 Pressure Indications

I load the 77's hotter than that.. you will likely run out of case capacity with the neck of the longer heavier bullets taking up more inside volume before you max out pressure. I can hear the Varget crunching now...

Keep going unless you have a tack driver load at that velocity.

shrpshtrjoe · Posted: Sun Nov 06, 2011 4:49 pm Post subject: Re: .223 Pressure Indications

I think they look pretty good . My 70 grain TSX Load is 24.5 grains of Varget

SyberShooter · Member Joined: Jul 23, 2010 Posts: 93 Location: Arizona

In addition to what others have said, also keep an eye out for metal flow marks on the brass rim from the ejector recess. It will show up as a shiny spot. You also didn't mention what primers you use. CCI are harder and the CCI 41 are military grade hard, but yours appear brass colored so I will guess they are Winchester, which are about middle of the pack as far as hardness and thickness of the metal cup IMO.
Another item I did not see is what type of gun are you shooting? Bolt or Semi or?

HayCreek · Member Joined: Sep 10, 2011 Posts: 36 Location: Central ND

Here's a link to data on primers. Should help in choosing the right primer for your loads:

www.jamescalhoon.com/p...essure.php

PaulS · Posted: Mon Nov 07, 2011 12:25 pm Post subject: Re: .223 Pressure Indications

Those primers look very nice. The ring around the pin strike looks to be from an oversize firing pin hole and not from pressure but check to be sure. The primers all have a nice radius around the pocket and don't seem to be showing much in the way of over pressure.
If that is the only indication of pressure you have at this point then I would say that things are fine.
Check case growth, head separation, signs of extractor impressions, loose primers and sticky cases - those are signs of immediate over pressure. Ptimers that are flat to the edges of the primer pocket are also a red flag of too much pressure.

Bushmaster · Posted: Mon Nov 07, 2011 2:13 pm Post subject: Re: .223 Pressure Indications

I wouldn't say a "red flag". Maybe a "yellow flag"...I have a Colt SAA in .357 magnum that will flatten the primers. and I mean FLATTEN with only 13.5 grains of 2400 under a 140 grain SJHP. I would need at least one more reason to consider over pressure than just a flatten primer.

slimjim · Posted: Mon Nov 07, 2011 3:38 pm Post subject: Re: .223 Pressure Indications

SyberShooter wrote:

You also didn't mention what primers you use. ... I did not see is what type of gun are you shooting? Bolt or Semi or?

Remington primers. AR but with the gas turned off (basically a straight-pull bolt action).

slimjim · Posted: Mon Nov 07, 2011 3:48 pm Post subject: Re: .223 Pressure Indications

Thanks shrpshtrjoe, HayCreek, SyberShooter, PaulS for additional information.