Is this overpressured?

[Ike Clanton]

Just tested 556 loads. New lake city brass. CCI 41’s, 2000mr powder starting under speers starting load with. 62gr gold dot. Started at 27 gr in increments up to 29 gr. (Max is 30.2) The primers all seem equally flattened with zero cratering. I reached the velocity I wanted at 28.5 gr (2936 FPS) with a 16 inch barrel. Once there I shot 30 rounds of xm193 then loaded up one of the 28.5 loads and let it cook for a couple minutes to check for temp stability. Primer looked the same but a small ring appeared that I assume is the bolt face. Velocity was 2960 on the cooked round. Does anything pop out as dangerously over pressured?

 

[cw308]

Not to me , the outer portion of the primer is still rounded not flattened at all , do you uniform your pockets ? Are your primers all bottoming when seating ?

 

[Ike Clanton]

I did not uniform the pockets and yes they’re all bottoming just fine. Do I need to mess with the primer pockets with new brass?

 

[RC20]

I can't see the ring well but you do have first stage pressure indication.

Primers are not the key, not to be disregarded but the wipe is one telling part.


Primer uniform is a fine tune step has nothing to do with pressure.

AR or bolt action? Data for AR or bolt (what gun did they run the tests in)

If 223 the LC brass is likely different as its 5.56 Mil spec.

 

[cw308]

Uniforming primer pockets on new brass. Uniforming the pockets only has to be uniformed once . Not a necessity but all my primers bottom to the same depth . As long as your bottoming your primers your fine but Im a benchrest shooter only so I go overboard on case prep. CCI primers work well for me also I'm shooting a bolt action not semi . When sizing from bolt face to datum you should be .003 , check your trim length also are you jumping or jamming your bullets . Trim length and jamming could cause undo pressure , just making sure .

 

[Unclenick]

Head looks like it started to flow. The primer pocket will be loose in no time, so, yeah, the pressure went over for the case a bit. You had almost a 1% velocity increase. Peak pressure probably increased something like 5% (varies with the powder). Not a big change, but it can be enough to throw some brass over the edge. Lake City used to reliably make heads enough harder to ensure that sort of thing didn't happen, but ATK changed the requirements in 2012 so commercial makers could be tapped as a qualified source more easily. Without a hardness test, I don't know what LC is putting out now. Federal makes brass with the LC headstamp for them sometimes.

 

[44 AMP]

Does anything pop out as dangerously over pressured?

No.

Primers didn't flatten, crater, or pierce. Cases didn't stick in the chamber, or rupture, there's no mention of excessive case head expansion, and of course the biggest clue, your gun didn't "blow up". So, DANGEROUSLY over pressure? No.

Higher pressure than desired, possibly, but dangerous? I don't see it.

 

[Ike Clanton]

I don’t know what jumping or jamming means?! Please enlighten me. These rounds were fired from a Ruger SR 556.

 

[Ike Clanton]

Here’s one that wasn’t cooked. Load was 28.5. Seems better to me.

 

[cw308]

Ike
Jump or jam is how far out is the bullet seated , if the bullet is seated into the rifling it's a jam , and a jump is the bullet is seated deeper in the case giving it a jump into the lands . Barrels have what the call free bore before the rifling starts . Jamming into the rifling can increase pressure also if your not checking case length , the case may not have enough room to stretch to release the bullet , will also cause pressure . I would guess your full sizing , bottoming the die to the shellholder to size the case and measuring listed OAL for the bullet and powder your using . If so your probably fine just check case length and trim to trim listed length in load book. Hope I Helped in some way .

Chris

 

[Ike Clanton]

Ahhh ok. You guessed it right, full resize and checking OAL. Thank you guys for all the help

 

[lamarw]

I can't say the following has any relevance or not. But I will ask a question and discuss some thoughts. I may end up learning something with the responses.

All the Lake City brass I have dealt with had to have the original crimped primer either swaged or cut out by some of numerous methods. I swag mine with a Dillon swag. Do you know how yours was done? Is it possible it was off centered? The picture almost makes it look off centered or it could just be the way the brass is sort of tilted giving me the impression in the picture.

Now I will read and learn from the responses.

 

[std7mag]

While i haven't seen Speers load data, looking at Alliant's your probably close to overpressure.
Alliant lists a 68gr Hornady at 28.0gr of PP2000. That is a compressed charge. Also lowest bullet weight for that powder.
2gr of powder is a pretty big jump for 8gr difference in bullet weight, and that small case volume.

I'm using 27.3 gr of PP2000 with Fed small rifle match primer and 69gr MatchKings.
This with LC brass.
I'm getting just shy of 3,100 fps, but this out of a 24" barrel.

Jumping and jamming refers to the distance from the bullet to the lands.
If you rifle is chambered for 5.56 Nato, you will have a decent jump for your bullets.
If your rifle is chambered for 223 Rem. Then it is going to be closer.

 

[cw308]

Ike , how long have you been into reloading , by the posts I'm reading your using a chronograph and loading for OAL for magazine feed . As long as your loading in safe ranges following information in his load book you should be fine . When you get deeper into reloading , reading up on case headspace , sizing from bolt face to datum line on shoulder and bolt face to ogive on bullet . It's one step at a time and at your own speed or you might go back to buying store bought . I like reloading as much as shooting , I load mainly for accuracy , some for the savings and shooting more . Ike what type of shooting are you into , target or hunting . I should have asked that question first and how long have you been reloading .

 

[Unclenick]

Lamarw makes a good point. That first photo does look like a ring crimp impressed off-center. That possibility hadn't occurred to me.

Ike Clanton, I don't know what your brass source is, but take a look at all of it to see if you see any more like that before you fired them.

The Lake City brass I have that has no crimp is all match brass or brass purchased in never-loaded condition (Federal's made-for-Lake City cases were available in 5.56 that way).

 

[Ike Clanton]

I think the photo may not be showing it well enough but that ring isn’t indented at all it looks more like a soot ring. None of the other brass has it. I got the brass from grafs and it’s new unfired. The 29gr brass looked the same at the 27gr even. so only one round made that weird black ring. As far as compression goes the 28.5 still has a little room and I can shake it to feel the powder. The 29gr does not. And yes I know these loads appear hot compared to alliants data but are still within spec for the gold dot data. Speer claims they use a boron-nitride coating that lowers pressures. Could be hog wash for all I know. I’ve only been reloading for 2 years and do it for fun. I don’t need super accurate loads or even high velocity loads but I figure if I’m going to the effort I may as well load something that is typically unavailable from the factory. In this case it was 556 pressured gold dots. I got the idea from Johnnys reloading bench on YouTube where he successfully put these rounds together

 

[cw308]

Ike with two years of reloading under your belt and reloading for quantity shooting , setting up your dies for full sizing and following the book listings for the bullet type and weight also powder charge you will be fine . No short cuts follow all the steps and you'll have no problems . Just check your brass for cracks and that ring that forms above the case head from stretching . Are you using a single stage press ?

 

[Ike Clanton]

I am using a Hornady progressive. Full size Hornady die with a very light lee factory crimp. I also chamfer and deburred all brass.

 

[cw308]

Ike I've been loading for 30+ years and I'm still on a single stage RockChucker . Hard to teach an old dog new tricks . Keep up the good work , it's such a fun sport . Be Safe , Hope I Helped in some way .

Chris

PS Great Name

 

[RC20]

Higher pressure than desired, possibly, but dangerous? I don't see it.

I would have to agree reluctant though.

If I had that I would consider it dangerous as I don't know what variation might push it into significant over pressure.

I back off from any pressure indicator I feel is valid. That is valid one.